Cementing Catalog

Cementing Services and Products Catalog

Cementing Services and Products Catalog

© Schlumberger 2003 Schlumberger 225 Schlumberger Drive Sugar Land, Texas 77478 All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transcribed in any form or by any means, electronic or mechanical, including photocopying and recording, without prior written permission of the publisher. TSL-4274 An asterisk (*) is used throughout this document to denote a mark of Schlumberger. †NExT

is a mark of NExT. is a mark of Den norske stats oljeselskap a.s. (Statoil). Netscape® is a registered trademark of Netscape Communications Corporation. Window® is a registered trademark of Microsoft Corp. ‡InstanSeal

Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix Reservoir solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix Research and development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x Quality, health, safety and environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi Key cementing technology highlights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Deepwater cementing products and services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Deepwater slurries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 DeepCRETE deepwater cementing solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 FlexSTONE Cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 DeepCEM additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Well stress analysis software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 CemCADE software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Advanced plug placement module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Offshore cementing skids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 DeepSea EXPRES offshore plug launching system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Surface dart launcher . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Subsea tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 A gas migration control service—GASBLOK service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Gas flow risk analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Routes for gas migration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 CemCADE software—placement and postplacement risk analysis . . . . . . . . . . 10 Cement slurry design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 High risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Low risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Slurry properties for gas migration control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Cement placement design and execution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Lost circulation systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Lost Circulation Advisor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Cementing Services and Products

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Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . InstanSeal system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . InstanSeal Cement system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ShearSEAL lost circulation fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PERMABLOK system for plugging zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CemNET advanced fiber cement to control losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ZONELOCK S sealing system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ZONELOCK SC permanent system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mud removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . WELLCLEAN II engineering solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pipe centralization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Displacement regimes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fluids design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . WELLCLEAN II simulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . WELLCLEAN II advisor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical washes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MUDPUSH spacers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . InterACT wellsite monitoring and control system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . System requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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14 14 15 15 15 15 15 16 16 16 16 16 17 17 18 18 18 18 18 19 19 19 19 19 19 20 20 20 20 20 20 21 21 22 22 22 22 24 24 24 25 25 25 26 27


Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CemCADE cementing design and evaluation software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Stress analysis model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i-Handbook oilfield data handbook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CemCRETE concrete-based oilwell cementing technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LiteCRETE low-density slurry system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DeepCRETE deepwater cementing solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DensCRETE advanced cement technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SqueezeCRETE remedial cementing solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CemSTONE Advanced Cement Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FlexSTONE Advanced Cement Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DuraSTONE Advanced Cement Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cementing slurry systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lightweight cements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LiteCRETE cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D049 lightweight cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Foamed cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


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29 29 29 30 30 32 33 33 33 33 39 40 41 42 42 42 43 43 43 43 44 45 45 45 45 46 46 46 47 49 49 49 50 51 51 51 51 53 53 54 54 54

v

Improved bonding cements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FlexSTONE cement—advanced flexible cement technology . . . . . . . . . . . . . . . . WELBOND cement—improved bonding cement system . . . . . . . . . . . . . . . . . . . . SALTBOND cement—cement system for cementing across salt zones . . . . . . RFC regulated fill-up cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SELFSTRESS expanding cement system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fast strength development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DeepCEM Cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ARCTICSET cement—cement system for use through permafrost . . . . . . . . . . Right-angle set cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cements for harsh environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acid-resistant cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Carbon dioxide-resistant cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Synthetic cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . UniSLURRY cement systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . UNIFLAC unified fluid-loss additive for cement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . UNISET set control additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cementing additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Accelerators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Antifoam and defoam agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Antigelation agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DeepCEM additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dispersants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Expanding additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Extenders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fluid-loss control additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gas migration control additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lost circulation control materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Retarders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Surfactants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Special additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Suspending and antisettling agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thixotropic additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . UniSLURRY additives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Weighting agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Spacers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chemical washes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

vi

55 55 55 55 56 56 56 56 57 57 58 58 58 58 59 60 60 60 61 61 61 61 62 62 62 63 63 63 63 64 64 64 64 64 64 64 64 65 65 65 65 65 65 65 65


Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CemSTREAK land cementing unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CPF-376 double-pump cement trailer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CPT-372 double-pump cement truck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Offshore cementing skids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Standard equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Optional equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LAS liquid additive system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CemCAT cementing computer-aided treatment software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SFM-C process control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nonradioactive densitometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Execution analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Postcementing analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cement evaluation services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sonic services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SlimAccess tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SCMT Slim Cement Mapping Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ultrasonic services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


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77 77 78 78 78 79 79 79 80 80 81 81 81 81 82 82 83 83 83 83 84 84 84 84 84 85 86 87 87 87 88 88 88 89 89 89 89 90 90 90 91 91 91 91 91 91 91 92

vii

USI UltraSonic Imager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cement integrity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pipe integrity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nonstandard environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

92 92 92 93 93 93 95 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Marks of Schlumberger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

viii


Preface Reservoir solutions Schlumberger has been supplying products and services to the oil and gas industry for more than 75 years. Our trained, highly qualified professionals team with operating companies to maximize asset values with reservoir solutions that combine best practices and advanced oilfield technologies with service quality and environmentally sound operations. As exploration and production activities have expanded, our relationships with operating companies have evolved. Today, we provide many services which help in finding hydrocarbons, constructing and completing wells to produce them, and stimulating the wells to maximize their production. We do this from service locations in all oil- and gas-producing areas of the world. We are committed to providing real-time solutions that make the finding and production of oil and gas more cost effective and that maximize recoverable reserves. With the movement toward a more holistic approach to oil and gas development, geoscientists and engineers gain a thorough understanding of the reservoir by using exploration and production product technology, field services, and project management skills along with software and information management services integrated with information technology (IT). Using this approach, the value of the reservoir is increased and the capital expenditures and negative cash flow are minimized.

Exploration

Delineation

Development

Maturity

Maximize production

+

Accelerate production

Maximize recovery

Cash flow

Time

Minimize capex

Defer abandonment

Minimize opex

– Reservoir optimization


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Preface

Traditional development

ix

Cementing plays a role in this process by providing zonal isolation in the wellbore. Highquality zonal isolation allows more accurate well testing to define the reservoir, maximizes recovery at the least cost (reduced costs for produced water and its disposal), and provides more effective stimulation through placement focused on the reservoir, more effective enhanced recovery and reduced abandonment costs.

Research and development Research has been a fundamental commitment since Schlumberger was founded in 1927. Despite fluctuations in business activity, our long-term commitment to research and development (R&D) is unwavering. During the market turndown in the late 1980s, we continued to spend heavily in R&D and we now invest nearly $1 million a day in research for oil and gas applications. Schlumberger employs top-level scientists, engineers and support personnel recruited from the best technical universities worldwide. Our research teams are multidisciplinary, embracing physics, chemistry, materials science, mathematics, statistics, computer science, signal processing, instrumentation, earth science, and solid and fluid mechanics. Our global R&D network provides a stimulating environment for the development of advanced technologies. This network includes ■ Schlumberger-Doll Research, Ridgefield, Connecticut, a center of excellence for oilfield research since the 1940s ■ Schlumberger Cambridge Research, Cambridge, England, which has been developing new concepts and techniques to help oil and gas companies find and produce hydrocarbons since 1981 ■ Schlumberger Austin Research, Austin, Texas, at the leading edge of information technology development since 1989 ■ Schlumberger Stavanger Research, Stavanger, Norway, established in 1999 as our first research satellite to conduct research activities at strategic locations around the world ■ Moscow Research, established in Moscow, Russia, in 2002 ■ Dhahran Research, established in Dhahran in 2001 ■ Schlumberger Reservoir Completions Center, near Houston, Texas, launched in 1999 to develop products and services for intelligent completions.

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Quality, health, safety and environment At Schlumberger we strive to continually improve the quality of our products and services; to protect the health, safety and property of our employees, our customers, our contractors and third parties; and to safeguard the environment in communities where we live and work. This proactive approach results in greater efficiency; reduced accidents, pollution and waste; and a more healthful workplace. Quality, health, safety and environment (QHSE) training, provided through state-of-the-art learning techniques, is mandatory for all Schlumberger personnel. All new employees receive both general and job-specific QHSE orientation prior to their first work assignments, and employees transferring to new positions or locations receive formal orientation about specific QHSE issues related to their new work environment. Our suppliers and contractors are evaluated, qualified and selected based on their ability to deliver a quality product or service in a safe, healthy and environmentally acceptable manner. Schlumberger practices go beyond environmental compliance. As stewards of the environment, we take proactive steps toward recognizing and eliminating detrimental practices. QHSE requirements are incorporated into all stages of product design, development and delivery. Prior to initiating a project or delivering a service, a formal assessment is conducted to ensure that all QHSE aspects have been addressed.

Training Schlumberger training is continuous—employees receive both formal and on-the-job training throughout their careers. We periodically assess all our training programs for content, quality and effectiveness, and we employ the latest technology to ensure that our training remains “best in class.” Our training emphasizes the use of IT. We have developed on-line and CD-ROM training modules and achieve full use of IT by providing worldwide connectivity to the internal Schlumberger communications network and to the Internet. Both new employees and those studying for advancement can use the Internet for their training courses. Schlumberger technical training programs sponsor on-line, in-house and field training in all phases of equipment selection, application and operation, as well as effective design, execution and evaluation. Structured training programs and seminars provide the latest information and technical knowledge, and we conduct directed learning programs and seminars around the world. Within Schlumberger, no education is ever really complete. Methods and techniques change, as do market conditions and regulatory guidelines. Following formal university and in-house training, employees continue to gain knowledge through experience and pre- and postjob sessions in which principles and practices are continually improved. The NExT† Network of Excellence in Training, an alliance of Heriot-Watt University in Scotland, Texas A&M University, the University of Oklahoma and Schlumberger, provides training that fills a learning gap for working professionals, both within and outside the company, to help them diversify their skill sets and learn about emerging technologies. Delivery methods include traditional classrooms, mentor-supported on-line distance learning, CD-ROM self-study programs and custom on-site courses. Our policy is to attract the very best graduates, then train and develop them. The majority of Schlumberger managers started in the field directly after graduating.

Preface

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Key cementing technology highlights Our high-quality cementing solutions are based on application of best practices, environmentally sound wellsite operations and innovative technology with safety as a highest priority. That technology includes Advanced Cement Technology, CemSTREAK* rapid deployment cementers, deepwater cementing with DeepCRETE* cement and DeepCEM* additives, and UniSLURRY* cement systems. Advanced Cement Technology increases the solids content of slurries by optimizing blends of several particles with different sizes in which the smallest particles fill the spaces between larger particles. Because of the higher solids content, the cement has greater strength, reduced permeability and greater resistance to corrosive fluids. The CemSTREAK unit is a lightweight, low-maintenance truck with four-wheel drive. It can handle almost any cementing application, even in hard-to-reach well locations. Equipment design makes rig-up, rig-down, cleanup and movement to next location fast and efficient. This design allows a single unit and crew to cement as many as six wells in one day. In deepwater cementing, DeepCRETE slurries, with their excellent slurry and set-cement properties, are combined with DeepCEM additives, providing improved rheology, rapid strength development and high strength. Compared with conventional cement technology, these technologies reduce the risk of shallow flow and shorten the waiting-on-cement (WOC) time and its associated high cost. UniSLURRY systems can be used for all types of cementing operations, including casing, liner, squeeze and plug cementing. Similarly, the additives are functional throughout the range of application conditions. This versatility simplifies the logistics of offshore cementing by reducing the number and quantity of additives that have to be transported and stored.

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Introduction Schlumberger provides high-quality services for well construction and remedial applications. These services are based on best practices, environmentally sound wellsite operations and innovative technology and always have safety as a first priority. Cementing is a process used to support and protect the casings in a well and to achieve or renew zonal isolation. Zonal isolation is required to prevent liquids or gases from flowing from one zone to another within the wellbore. This isolation allows the completion and production and subsequent abandonment of the well at the lowest possible cost. Isolation allows more accurate well testing to define the reservoir, maximum recovery at the least cost (reduced costs for produced water and disposal), more effective stimulation through placement focused on the reservoir, more effective enhanced recovery and reduced abandonment costs. Without isolation, the cost of each of these processes is increased and its effectiveness is reduced. When isolation is not achieved by the primary cement job (cementation of the casing string) a squeeze job is required to correct the deficiency. Squeeze jobs are also used during the well’s life to meet changing objectives as the well and field age. Occasionally, cement plugs are set in the well to allow changes in drilling. Plugs are also used to isolate intervals within the well when it is depleted and abandoned. All these cementing treatments require careful design of the cement systems to provide the required properties of the slurry before setting and of the cement once it is in place and set. Designs must consider the conditions in the well at the time of cement placement as well as conditions that may occur at any time during the life of the well. In addition to the design of the slurry and set-cement properties, the mechanics of the placement process must be designed to accomplish optimal mud removal and cement placement. On location, the cement must be properly mixed to achieve the required properties and pumped into place, maintaining the integrity of the well. To achieve the cementing objectives, various additives can be used to modify the slurry and set-cement properties. Specific cement slurry systems are employed to meet especially demanding applications. A new, innovative approach to cementing is Advanced Cement Technology. This technology utilizes principles from the concrete industry, specially adapted for oilfield use, to formulate slurries with lower water content. These advanced principles eliminate the problems of conventional slurries, which require high water content for optimal pumpability that ultimately reduces the compressive strength of the set cement. This Advanced Cement Technology has two families; CemCRETE* concrete-based oilwell cementing technology and CemSTONE* technology. CemCRETE technology increases the solids content of the slurry using a custom-designed particle-size distribution. More solids in the cement mean greater compressive strength, reduced permeability and greater resistance to corrosive fluids. CemSTONE technology uses this high solids content together with particles having specific properties to modify the set-cement performance (such as durability, flexibility and expansion) to the needs of the well. Using stress analysis modeling software, cements can be designed with properties to provide isolation for the life of the well.


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Introduction

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Our cementing software is used worldwide by Schlumberger engineers. CemCADE* cementing design and evaluation software, which allows simulation based on well data and formation conditions, is used to plan the proper placement of the slurries and ensure the integrity of the well is not compromised. DESC* design and evaluation services for clients improves communications and solutions development by placing a dedicated Schlumberger engineer in the client's office with access to information hubs, technology centers and the most complete family of application software in the industry. Purpose-built and highly specialized mixing and pumping equipment is employed to properly execute the treatment, while the CemCAT* monitoring and recording system provides a record of the treatment. Use of the CemCAT record, along with design parameters and placement and isolation evaluations such as those provided by USI* UltraSonic Imager logs, allows the design engineer and service team to make performance enhancements and use principles of continuous improvement to enhance the value of the cementing process.

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Services Deepwater cementing products and services Deepwater drilling poses unique challenges for cementing. Large-diameter casings are set in poorly consolidated formations, frequently with a narrow pore-fracture pressure window and high potential for shallow-flow hazards (water or gas). Compounding the problems is the low temperature found at the sea bottom and the first few thousand feet below mudline. With subsea wellheads, launching cement wiper plugs is also more complicated. Logistically, the distance from shore makes versatility in cement slurry design an important consideration. Add to this the difficulty of remedial work in the deepwater environment, and annular sealing throughout the life of the well becomes more critical. Abnormally pressured sands, with a high probability of shallow-water or gas flow, characterize many deepwater geological environments. Such flows present problems in cementing operations, affecting the integrity of the well. Consequences of uncontrolled shallow flows include subsidence, compromised seafloor stability, loss of well support and buckling of structural casing, and compromised wellbore integrity, resulting in well control problems and potential loss of the well and supporting structures. Schlumberger provides innovative products and services for solutions to deepwater cementing challenges. DeepCRETE slurries, DeepCEM additives and GASBLOK* gas migration control slurries deliver the properties necessary to provide rapid setting, control of potential flows and the long-term isolation needed to ensure the integrity of the well and protect the environment. The DeepSea EXPRES* offshore plug launching system allows the efficient release of bottom and top wiper plugs in subsea cementing heads to prevent cement contamination and control displacement. Engineers use CemCADE software, proven over two decades, for placement design and to assure well security and control. Offshore cementing skids, built for performance and reliability, provide the means to efficiently mix and pump the high-quality slurries required in this tough cementing environment.

Innovative deepwater cementing solutions provide effective and efficient cementation of wells drilled in deepwater.


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Deepwater slurries DeepCRETE cement slurry systems are based on CemCRETE Advanced Cement Technology. DeepCEM additives minimize risk of shallow flow, enhance strength development, reduce WOC time and provide low permeability of the set cement. When needed, FlexSTONE* Advanced Cement Technology slurries can be employed to provide set-cement durability, with annular cement sheaths able to withstand changing downhole stresses without failing.

DeepCRETE deepwater cementing solution The DeepCRETE deepwater cementing solution is a combination of efficient technologies producing slurries that let you cement weak deepwater zones where low temperature and potential shallow flow exist, yet quickly return to drilling. DeepCRETE technology, which provides lowdensity slurries with excellent strength and low permeability, is ideal in the environment encountered in deepwater well construction. Without requiring special equipment or personnel, DeepCRETE slurries isolate the formation with a light cement that develops strength rapidly. This is done using the CemCRETE concept and DeepCEM liquid additives to deliver short transition time and rapid setting at low temperatures. With CemCRETE technology, permeability and strength are independent of slurry density and superior to those of conventional cements. See page 40 for additional information on CemCRETE Advanced Cement Technology.

FlexSTONE Cement FlexSTONE systems offer mechanical properties that can be engineered to meet the changing stresses in the wellbore; excellent flexibility and chemical resistance while maintaining lower permeability and good compressive strength. FlexSTONE systems, with these properties customized to the well, will resist stresses and maintain isolation. These slurries also expand to seal any microannulus. FlexSTONE cements are engineered to be more flexible than the formation they seal, and expansion of the cement sheath occurs both outwards (toward the formation) and inwards (toward the casing), thus assuring complete hydraulic isolation. See page 48 for additional information on FlexSTONE Advanced Cement Technology.

DeepCEM additives DeepCEM liquid cementing additives were created for short transition time and early compressive strength development. Such properties are necessary for isolation and early casing release to ensure successful cementation in the unconsolidated, low-temperature environment of the surface and conductor casings in deepwater wells. When combined with Schlumberger GASBLOK gas migration control technology, DeepCEM slurries provide the solution to shallow gas or water flow control. These additives can be used in foamed cement slurries. Use of these systems allows elimination of the special blends often needed to overcome challenges related to low temperature in deep ocean drilling. DeepCEM additives include the nonretarding dispersant (D185) and cement set enhancer (D186). The nonretarding dispersant provides the dispersion required for good slurry design without retardation at low temperatures. Even at the low temperatures encountered in deepwater wells, D186 set enhancer is more effective for early strength development than standard cement accelerators such as calcium chloride.

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Well stress analysis software Stress analysis modeling software is used to identify potential well stresses and their magnitude throughout the life of the well. Engineers then design the appropriate set-cement properties to withstand these stresses. Where required, FlexSTONE systems are designed with the properties identified using this software. FlexSTONE systems are purpose-built to offer control over properties not possible with conventional oilwell cement. These include such set properties as flexibility and expansion for continuous well integrity and zonal isolation for the life of the well.

CemCADE software CemCADE software can be used to design all primary cementing operations, from large-diameter conductor casing to the deepest liners. Use of CemCADE software helps the engineer ensure that well security is respected at all times and at all points in the well during the cementing treatment. By coupling centralization calculations with a numerical fluid placement simulator, CemCADE software allows easy flow regime and annular flow rate selection. It also aids in design of wash, spacer and slurry for optimum displacement of mud and cement placement. Displacement optimization helps to prevent channeling, ensuring zonal isolation. The program utilities and underlying physics are enhanced continually to reflect the latest developments in cementing technology. Of particular interest for deepwater operations are the temperature simulator, gas migration predictor, and swab and surge pressures calculator. The temperature simulator allows a calculation of fluid and wellbore temperatures that considers wellbore environment parameters such as seawater temperature and current. Better knowledge of the temperature makes selection of retarder or accelerator concentration more accurate as well as allows WOC time determination based on modeled wellbore temperatures.

Advanced plug placement module Due to the high operating cost in deepwater, time for any operation must be minimized. This is especially true when setting cement plugs. A module assists engineers in designing plugs to minimize contamination during placement, resulting in much higher plug-setting success. This success minimizes the need for repeat plugging operations, thus saving valuable rig time. See page 29 for additional information on CemCADE software.

Offshore cementing skids The performance and versatility of Schlumberger skid-mounted cementing units make them the best option for offshore, high-pressure pumping services. These state-of-the-art units, capable of delivering up to 1490 kW [2000 hhp] of power, can be used as backup or supplemental mud pumps as well as efficient cementing units. Power to drive the pumps comes from high-performance diesel engines or air-cooled electric motors. These units are fitted with state-of-the-art sensors for data acquisition and monitoring, and an optional remote control system permits operation of the unit from an adjacent control room. When a Schlumberger SLURRY CHIEF* cement mixer is used in combination with the skid, cement-mixing rates of more than 1.9 m3/min [12 bbl/min] can be achieved for optimal job execution. See page 83 for additional information on offshore cementing skids.

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Cement mixing and pumping units are specially designed for use on offshore drilling rigs.

Liquid additive metering systems provide versatility in the ability to adjust cement slurry properties right up to the time of the cementing treatment. This is especially beneficial in deepwater operations, because the requirements may not be known until the hole section is drilled. If dryblended cements were used, there would be considerable time spent waiting for testing, blending and delivery if requirements are not known until the section is drilled.

DeepSea EXPRES offshore plug launching system The Schlumberger DeepSea EXPRES offshore plug launching system is a remotely operated system for releasing cementing wiper plugs from a subsea tool. It combines a design for safety with highly functional, high-quality plugs to provide a reliable system for launching plugs in a subsea system. This system uses solid plugs, which are more reliable than the flow-through type. Plugs are released with minimum or no shutdown of the cementing operation.

Applications ■ ■

Casings hung from subsea hangers Top and bottom plug operation in casing sizes from 244 to 508 mm [95⁄8 to 20 in.]

Benefits ■ ■ ■ ■ ■ ■

Dart release takes only seconds, reducing rig time. Uninterrupted pumping improves mud removal. High pumping rates allow improved mud removal. Casing pressure test can be combined with bump. Casing running tool can be activated without removing treating lines. Remote operation improves safety.

Features ■ ■ ■ ■ ■ ■

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Wiper plugs are efficiently designed. Fluids are not pumped through the plugs. Plugs do not contact casing wall during rig-up. Surface pressure provides positive indication of each plug release. Plug launch qualified at flow rates up to 1.9 m3/min [12 bbl/min]. Optional three plugs separate up to four fluids. Cementing Services and Products

Surface dart launcher A surface dart launcher (SDL) holds the darts, which are launched during the cementing operation. When they reach the subsea tool, these darts release the casing wiper plugs. The standard configuration can hold two darts up to 610 mm [24 in.] long. The SDL is modular, so additional hardware can be added to launch more darts. Fluids are pumped around the outside of the dart holder. To launch a dart, the EXPRES* system power pack, operated from the rig floor, rotates the valve a quarter turn. This rotation aligns a hole in the valve body with the dart and launches the dart. The SDL offers full top-drive compatibility. The fluid inlet swivel provides two 50.8-mm [2-in.] WECO connections and permits pipe rotation with the treating lines attached. The 114.3-mm NC50 [41⁄2-in. IF] connections at top and bottom allow the entire string to be supported and rotated. Both circulating mud and displacement fluid can be pumped through the topdrive. Darts offer several advantages over “free fall” balls. The darts wipe the inside of the drillpipe and separate the fluids to prevent contamination. They also provide positive fluid displacement. The time and uncertainty spent waiting for a ball to reach the downhole assembly are eliminated.

DeepSea EXPRESS offshore plug launching system is a reliable tool for releasing cement wiper plugs when subsea hangers are used.

Services

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Subsea tool The subsea tool (SST) retains the casing wiper plugs until they are released by the arrival of the darts. Hydraulic pressure acting through the dart and a rod releases the plugs. The SST accepts up to three plugs for 219- to 340-mm [85⁄8- to 133⁄8-in.] casing or two plugs for 406- to 508-mm [16- to 20-in.] casing. The deepwater cementing products and services portfolio of Schlumberger provides all the components required to provide zonal isolation for the life of the well.

A gas migration control service—GASBLOK service Gas migration, or annular gas flow, is a problem that has plagued the industry for many years. There is no one cause of gas migration, nor is there any one solution to it. To effectively control gas migration, the nature of the problem must be understood so that the proper techniques can be applied. This implies a careful analysis of the potential for flow as well as an integrated approach to its control. During this analysis, one must consider not only the potentially productive intervals, but also the intervals that may not be economically productive, including gas stringers, which can exist behind any casing string. Among the reasons for gas migration are an uncemented channel, failure to maintain overbalance pressure before and during cementing, loss of overbalance pressure after cement placement, development of flow paths after cement setting, and insufficiently low permeability to prevent gas from flowing through the set-cement matrix. Obviously, each of these arises from different mechanisms. Therefore, control of gas migration must address the totality of the sources for flow. Controlling gas migration takes much more than just complex cement slurry design. Slurry design addresses only one facet of the complex problem, albeit a very key one. An element of the overall process of controlling gas flow is achieving zonal isolation through the intervals containing the gas. An additional element is maintaining overbalance pressure during the critical transition period. The final element is preventing gas from migrating along the annulus. The GASBLOK service considers these elements as three phases of the process: remove the drilling fluid to provide the proper environment for zonal isolation, delay gas entry, impede propagation of the gas.

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Each of these phases requires careful analysis and design to achieve the desired overall result—a well that is free of gas migration. The first step, that of achieving zonal isolation, is accomplished by the cement, but only after the drilling fluid has been removed from the wellbore to allow cement to fully occupy the annulus between the borehole and the casing. Mud removal is accomplished by techniques that have been developed by Schlumberger through the years, culminating in the WELLCLEAN II* engineering solution for mud removal. This solution considers the factors that impact mud removal and provides a systematic approach to removal of mud. The second step is to design the placement process so that an overbalanced condition is maintained until late in the transition of the cement from a liquid to a solid. The nature of the setting process makes it difficult to maintain overbalanced pressure; after placement, cement undergoes a gradual gelation, resulting in loss of hydrostatic pressure. Ideally, the pressure is maintained above formation pressure until the cement is set. In practical terms, this is extremely difficult to do. Another option is to minimize the time between development of gel strength and setting while maximizing the overbalanced pressure (without risking breaking the well down). This is done by analyzing the pressures in the well and employing options that maximize the overbalanced pressure. Several tools in CemCADE cementing design and evaluation software assist in this step. Obviously, a component of this step is the design of the slurry. The third step, impeding propagation of the gas, depends on the use of slurries with special properties so that gas cannot invade and migrate along the cemented annulus. Special properties, such as those provided by GASBLOK slurries, are required during the critical transition period as well as after setting. Additionally, to maintain isolation for the life of the well, CemSTONE Advanced Cement Technology may be required.


Zonal isolation in gas wells Prevention of annular gas migration from nuisance gas stringers

Benefits ■ ■ ■ ■

Minimized risk of gas migration Long-term solution Reduced exposure to hazardous gas flow More trouble-free operations

Features ■ ■ ■ ■ ■ ■ ■

Services

Tailored to specific well conditions Effective at any density Effective at any temperature Compatible with CemCRETE and CemSTONE technologies Integrated solution employing materials and techniques Materials with low environmental impact Engineering tools to assess risk and tailor treatment to severity

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Gas flow risk analysis A risk analysis is an important element in the design for gas migration control. Such an analysis incorporates knowledge of all the gas sources (from openhole logs and drilling logs), the potential for gas flow from each source and the potential routes through which gas can migrate. Routes for gas migration

Gas migrates in a well when the pressure becomes underbalanced. If the cement is in place and set when this occurs, the potential for flow depends on the integrity of the cement, both its complete filling of the annulus and its mechanical durability. Paths for gas flow develop as a result of incomplete mud removal (a mud channel), free fluid development in the cement slurry, or an interfacial gap (microannulus) at the cement-pipe or cement-formation interface. An additional path can be created if the cement fails mechanically, producing a crack along its length. These paths can also be created by changing mechanical stresses in the well. A path can be created if the well becomes underbalanced before the cement has developed sufficient strength to prevent its propagation through the column; that is, while the cement is unset. In this case, gas can migrate through the unset cement, forming a channel. CemCADE software—placement and postplacement risk analysis

CemCADE cementing design and evaluation software has two tools that aid in preventing gas invasion of the cement before it has developed adequate strength to control gas flow. The first is a tool common to most cementing simulators, an analysis of the fluids and pressures in the well during and after the cementing process to determine well security and control. If an underbalanced condition develops during cement placement, a warning is given and the fluids and/or placement process are redesigned. A second tool, called postplacement analysis module, provides the design engineer with an indication of the relative risk of gas migration based on the degree of overbalance and the well geometry. The engineer can then assess variations in slurry placement and treatment execution variables to propose the lowest-risk method of cementing the well. In cases where the risk is judged to be small, less-aggressive solutions can be proposed; conversely, if the risk is judged to be high, more aggressive solutions should be considered.

Very critical 25 Pa 50 lbf/100 ft2

Critical

Moderate 75 Pa 150 lbf/100 ft2

Low

150 Pa 300 lbf/100 ft2

Very low 250 Pa 500 lbf/100 ft2

Postplacement analysis provides the design engineer with a relative degree of risk for use in selection of methods of controlling gas migration.

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Cement slurry design Slurry design for controlling gas migration requires attention to the entire realm of slurry and setcement properties. These include free fluid, fluid loss, rheology, thickening time, gel strength development, setting profile and set mechanical properties including permeability. In wells with a high risk of flow, slurries with special properties to stop gas invasion and flow may be required. Their use is normally based on the perceived risk of gas flow. After assessment of risk, the design engineer develops the slurry design and placement accordingly. For scenarios with low risk, control of free fluid, rheology, gel strength development and fluid loss may be adequate to control gas flow. Where the risk is higher (or uncertain), the use of more complex slurries with special properties to contain the gas are required. High risk

Schlumberger slurries for high-risk gas migration scenarios have very special properties. These slurries are called GASBLOK slurries, proven for over two decades. GASBLOK slurries are part of the overall GASBLOK technology, a systematic approach to solving the gas migration problem. These slurries use either a specially designed and patented latex additive or a customized microgel polymer. The latex provides unique properties to cement slurries and the set cement. Being a suspension of solids, the latex provides excellent rheological properties and control of gelation without affecting the hydration process. Free fluid is easily controlled and setting is rapid. The finely divided latex particles provide efficient pore-blocking in the developing cement matrix during the transition from liquid to solid and in the set cement. This pore-blocking minimizes the invasion of the cement by gas and prevents its movement. Microgels provide similar effects, but with specially designed hydrated polymer particles. The GASBLOK family of additives includes D500 GASBLOK LT additive, D600G GASBLOK MT additive, and D700 GASBLOK HT additive for low, moderate and high temperatures, respectively. A surfactant, D701 GASBLOK stabilizer, is used to control transition time and setting in certain cases. These additives, used so successfully in controlling gas migration for the past two decades, have been modified to make them acceptable in more environmentally sensitive areas, such as the North Sea. Low risk

When the risk of gas migration is judged to be low, less-aggressive designs are required. Slurries can be designed with more conventional fluid loss additives in place of the GASBLOK latices or microgel. Besides fluid loss control, excellent slurry and set properties must still be maintained. Slurry properties for gas migration control

Laboratory and field evaluations have demonstrated that several properties of cement slurries are critical in controlling gas migration.

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Poor mud removal (rheology)

Free fluid

High fluid loss

Bulk shrinkage

Gas channeling along interfaces

Gel strength development

Cement hydration

Result ■ Interzonal communication ■ Pressure-charged formations ■ Gas to surface ■ Blowout

Chemical contraction

Gas channeling within cement matrix

Unplanned costs ■ Remedial work ■ Lost production ■ Damage to equipment and facilities Many slurry properties must be correctly designed for success in cementing across gas-bearing formations.

Fluid loss control is important, because maintaining the proper ratio of water to solids is critical to maintaining the rheological properties for effective placement of the slurry as well as preventing premature gelation. Premature gelation will lead to long transitions to a set matrix and result in unacceptably early hydrostatic pressure decay. Such hydrostatic pressure decay would in turn lead to an underbalanced condition. If occurring before the cement develops a solid matrix, this situation can easily lead to gas invasion of the cement and migration along the annulus to points of lower pressure. Simultaneously, the proper water/cement ratio must be designed and maintained to control slurry stability. An unstable slurry can allow the development of free fluid and/or solid sedimentation. Free fluid can create a water channel in the column of cement, leading to gas flow. Sedimentation can lead to changes in density of the slurry and result in inadequate fluid pressure to control the formation pressure. An additional impact of the water/cement ratio is that of the slurry and set-cement permeability. As the water/cement ratio increases, so does the permeability of the cement matrix. A permeable cement matrix makes control of gas more difficult; if permeability is sufficiently high, there may be migration through the matrix after setting.

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The setting behavior of the cement is important for several reasons. Initially, early setting determines the relationship of strength development to hydrostatic pressure decay (and underbalance and gas flow initiation). Subsequently, permeability, shrinkage, expansion and long-term durability are controlled by the setting behavior. As discussed previously, permeability must be kept low to minimize or prevent gas flow through the set-cement matrix. Shrinkage can result in the development of microannuli between the cement and pipe or wellbore wall. Shrinkage can also result in radial cracking of the cement, which provides another path for gas to flow. Long-term durability can be enhanced with CemCRETE and CemSTONE Advanced Cement Technology. CemCRETE and CemSTONE slurries are highly effective in achieving the properties necessary for gas migration control. CemCRETE slurries provide low-permeability cement, even at very low densities. They also have excellent slurry properties (stability, rheology, etc.). CemSTONE slurries have very high durability and, if required, can be designed to expand. When coupled with GASBLOK technology, both slurry systems provide excellent properties to meet the demanding requirements for gas migration control.

Cement placement design and execution The control of gas migration requires more than special slurries. Successful control involves many elements. Mud removal design—Mud removal is critical to achieving zonal isolation. Schlumberger engineers use the advanced WELLCLEAN II technology for designing the flow regime, fluids and pumping schedule to achieve mud removal. Coverage of zone of interest—There must be adequate slurry covering all the gas-bearing formations, not just the pay zone. Maximize overbalanced pressure—Pressure decay, an unavoidable consequence of the change from slurry to set cement, results in loss of overbalance. By maximizing the overbalance pressure, the age and therefore the strength of the cement is greater at the time an underbalanced condition is reached. The Schlumberger engineer uses the postplacement tool in CemCADE cementing design software to optimize the overbalanced pressure. Gas migration risk—The Schlumberger engineer uses the postplacement module of CemCADE software to evaluate design and operational effects to lower risk of gas flow. Application of pressure on the annulus following placement, as well as other operational procedure changes, can reduce the risk. Well security and control—Throughout the cementing process, the pressures in the well must be sufficient to control the gas yet not be so high as to cause lost circulation. The U-tube simulator in CemCADE cementing design software provides a plot showing the pressures at all times during the cementing treatment and aids the engineer in maintaining security and control in the well. Hydrostatic-pressure-relieving devices—At times, openhole casing packers are used to isolate sections of the wellbore. Care must be taken with these devices because they have the effect of preventing full hydrostatic pressure transmission and can aggravate the problem. Any loss of volume below the packer (such as by fluid loss) can result in very rapid hydrostatic pressure loss and subsequent rapid gas migration through the entire section isolated by the packer. Gas pressure can build up beneath the packer and cause failure of the packer. Well design—Although not a common approach to solving gas migration, changes can be made to the well design to change the level of risk. Using the postplacement module of CemCADE software, the Schlumberger engineer can work with the well design team to evaluate parameters and redesign the well for the lowest risk for gas flow. An example of a well parameter that plays a part in gas migration risk is the annular gap size. Increasing the annular gap will lower the risk of gas migration. Schlumberger engineers integrate all the elements of gas migration control. The risk analysis, the complete placement design and the optimum design of the cement slurries minimize the risk of gas migration, providing zonal isolation and well integrity.

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Lost circulation systems Lost circulation is a frustrating, costly and time-consuming problem. Some of the major consequences of lost circulation include increased cost resulting from ■ ■ ■ ■ ■

poor or no removal of cuttings, requiring additional wiper trips stuck drill pipe excessive mud lost remedial work to cure losses rig time required to cure losses.

Reservoir damage and loss of well are also possible as a result of ■ ■ ■

lack of zonal isolation caused by poor cement coverage formation damage resulting from mud losses blowout after a drop in hydrostatic pressure.

To select the correct technique to effectively solve lost circulation, it is necessary to know the reasons for the losses; i.e., the type of loss and the drilling history. Very often lost circulation treatments fail because of a lack of information such as the types of losses and their relative depths. A lack of knowledge can lead to selection of the wrong treatment, which usually results in poor success, excessive costs and time, and the frustration caused by repetitive failures. Lost circulation can occur at any time in the life of the well. During construction, lost circulation can be encountered while drilling and while cementing. These problems are solved by different methods. A tool for identifying the best solution is the Lost Circulation Advisor.

Lost Circulation Advisor The Lost Circulation Advisor is software developed jointly by Schlumberger and M-I, LLC. It is a case-based reasoning tool, used to analyze lost circulation problems and recommend the best treatment to control the losses. The advisor is a knowledge-management software based on the field experience and the lost circulation expertise of field engineers. Regardless of the loss type (partial or complete) and the operation (drilling or cementing), the advisor guides field personnel toward the best lost circulation treatment. Based on the input data that include well data, previous lost circulation treatments, operation (drilling or cementing), estimated loss rate and openhole stratigraphy, the advisor identifies the type of loss and its depth. Finally, the Lost Circulation Advisor recommends the best lost circulation treatment from a list of generic and specialized systems available from M-I, LLC and Schlumberger. Once the best lost circulation treatment is identified, complete technical data are provided for the design of the treatment. Applications ■

All types of lost circulation

Benefits ■ ■ ■ ■ ■

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A simple software based on knowledge management, not complicated mathematical models A systematic and analytical approach to lost circulation A guide to the best lost circulation treatment and the relative depths Validated cases for more precise solutions A low-cost solution to complex problem


Features ■ ■

■ ■ ■

Uses case-based reasoning Identifies whether the losses are to permeable formations, natural or induced fractures, vugs, or cavernous formations Estimates the depth of losses Identifies the best lost circulation treatment based on the operation (drilling or cementing) Provides technical information for use in designing the recommended treatments

InstanSeal system The InstanSeal‡ system is a unique technology for combating high mud losses. It is often more time- and cost-effective than other lost circulation control methods. The InstanSeal system uses shear activation to trigger formation of a rigid gel. This unique activation method saves crucial drilling time and money over other lost circulation methods. The base fluid for InstanSeal lost circulation control is an emulsion. The emulsion contains gelling polymer and crosslinker in separate phases. The emulsion is converted when the slurry is pumped through the nozzles in the bit, crosslinking the polymer. This results in rapid action and excellent control of polymer placement into the loss zone.

Water phase containing high concentration of polymer Oil phase Crosslinker particle 500 psi

Cement Emulsion

Set gel

Activation of the InstanSeal system is by shearing force rather than chemical action. This technology makes placement across the loss zone more certain.

Applications ■

Severe lost circulation

Benefits ■ ■ ■

Internally activated Valuable rig time savings Downhole mixing of fluids not required

Features ■ ■ ■ ■ ■ ■ ■

Services

Use to 95°C [200°F] Set time independent of bottomhole temperature (BHT) Can be weighted to 1440 kg/m3 [12 lbm/gal] Requires no tripping Set time short and adjustable Is acid-soluble when set Can be mixed up to 3 weeks before use 15

InstanSeal Cement system The InstanSeal Cement system is similar to the InstanSeal system, but has powdered cement added to the oil phase. Once the emulsion is broken and the system forced into the loss zone, the cement will become wet with water and will set. This system is used when a more permanent solution is required. InstanSeal Cement is stable to 110°C [230°F].

ShearSEAL lost circulation fluid ShearSEAL* shear-activated, high-temperature lost circulation fluid is a highly innovative lost circulation solution. The system can be used at temperatures to 163°C [325°F]. If necessary, it can be weighted to 2040 kg/m3 [17 lbm/gal]. It can be mixed using batch-mixing techniques or continuously with a static, in-line mixer. The crosslinked gel is not shear sensitive, has improved elasticity, exhibits no syneresis and is removable with light acid. The base fluid for ShearSEAL lost circulation control is an emulsion. The emulsion contains gelling polymer and crosslinker in the oil phase. The emulsion is converted and the polymer crosslinked when the slurry is sheared through the nozzles in the bit. For activation, only a 1725-kPa [250-psi] pressure drop at the bit is required. Activation at the bit results in rapid activation and excellent control of placement of the gelling polymer into the loss zone. In addition to use for lost circulation control, ShearSEAL system can be used to create support beneath a cement plug and to fill the rathole during cementing of the casing. Applications ■ ■

Severe lost circulation Support for cement plugs


Internally activated Rig time savings No downhole mixing of fluids

Features ■ ■ ■ ■ ■ ■ ■

16

Use to 163°C [325°F] Set time independent of BHT Can be weighted to 2040 kg/m3 [17 lbm/gal] Requires no tripping Set time short and adjustable Is acid-soluble when set Can be mixed up to 3 weeks before use


PERMABLOK system for plugging zones The PERMABLOK* fluid system to permanently plug a zone is used to solve lost circulation problems (either during drilling or before cementing), plug high-permeability zones and provide consolidation of weak formations. Such high permeability can appear as interconnected porosity within the matrix, or micro- or macrofissures including vugs. PERMABLOK systems are internally activated solutions with very low initial viscosities. The solutions have controlled gelling (pumping) times and set to form a rigid, drillable gel. With a temperature limit of 79°C [175°F], these solids-free liquids have many applications, including pumping through the bit. PERMABLOK systems can also be used to permanently plug formations and to consolidate loose formations that threaten, slow or halt drilling.

CemNET advanced fiber cement to control losses When cement is pumped downhole, some of the cement can be lost into natural fractures, fissures, vugs or highly porous zones even when the fracture pressure is not exceeded. CemNET* advanced fiber cement is composed of an inert, fibrous material capable of forming a network across the loss zone, allowing circulation to be regained. The CemNET fibers are engineered to an optimal size for sealing such loss zones. CemNET fiber (D095 or D096) is compatible with most cementing systems and additives and does not affect the cement properties. CemNET fiber is added to the slurry in the mixing tub or a batch mixer. If CemNET fibers to be used only in the portion of the slurry to be pumped downhole where losses are expected to occur. Once dispersed in the slurry, the CemNET fibers create a physical network that forms a bridge when flowing past loss zones, resulting in control of losses and improved fill of the cement during treatment. CemNET fibers seal formations having potential for losses during treatment, reducing both the amount of cement used and disposal during cleanup. If CemNET fibers are not used, operators often pump excess cement in anticipation of losses to fractures, fissures, vugs or highly porous zones. By adding CemNET fibers to the existing cementing program, well costs are lowered. These cost reductions are a result of smaller excesses of cement needed to achieve returns, reduced disposal of large excesses returned to surface and, more significantly, reduced remedial cementing in the event that cement is not returned to surface. In some cases, the use of CemNET fiber in the cement has resulted in regained returns.

CemNET fibers are inert and require no special handling. They can be readily dispersed in water-base fluids such as cement. An interlocking network is formed, allowing the cement to bridge and resume circulation.

Services

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Applications ■ ■ ■ ■

Regain circulation while cementing Most cement slurry formulations All temperatures Any slurry density

Benefits ■ ■ ■ ■ ■ ■ ■

Minimizes losses during cementing Raises cement tops Helps prevent cement fallback Reduces the need for costly remedial operations Reduces excess cement requirement Makes cement returns more predictable, thus decreasing disposal costs Provides coverage of loss zones during cementing operations

Features ■ ■ ■ ■

Fibers added directly to the slurry during mixing, without dry blending No effect on cement properties Compatible with most cementing systems and additives Forms bridging network in the slurry

ZONELOCK S sealing system The ZONELOCK* S permanent zone sealing system is a solution of silicate that forms a rigid, semipermanent gel when in contact with a heavy calcium or sodium brine. The system is composed of two solutions: one silicate and one calcium chloride. This system is very effective and works independently of temperature. It can be used to effectively seal problem zones of brine production or lost circulation. The solutions can be pumped in multiple stages to cover the zone more effectively.

ZONELOCK SC permanent system The ZONELOCK SC system includes the ZONELOCK S system followed by a spacer and then cement. When the cement contacts the gel resulting from the silicate-calcium brine solution, the cement sets very rapidly. This ZONELOCK SC system forms a permanent seal that can only be removed by drilling.

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Mud removal WELLCLEAN II engineering solution Effective mud removal is considered the most basic requirement for cementing success. Failure to achieve removal of mud can result in failure to isolate productive intervals, allowing production of unwanted fluids, misapplication of stimulation treatments, and chronic issues of sustained casing pressure and gas migration. When such conditions exist, additional costs and efforts are incurred. Applications ■

■

Mud removal in oil and gas wells, including deviated, extended-reach, horizontal and injection wellbores Oil-base mud (OBM) or water-base mud (WBM)


Enhances zonal isolation Eliminates production of unwanted downhole fluids Reduces occurrence of sustained casing pressure Minimizes casing corrosion through improved cement bonding Reduces remedial operations and their associated costs

Features ■ ■ ■ ■ ■

An engineered approach using specialized tools and products Ability to assess the effect of all relevant parameters on the mud removal process A wide range of flexible preflush systems for all application conditions Proven results in the field Environmentally friendly spacers

Recognizing that effective mud removal cannot be achieved without considering the effect of all relevant parameters, the WELLCLEAN II engineering solution utilizes innovative products and tools to design cement placement for effective zonal isolation. These products and tools include ■ optimized chemical wash systems ■

a wide range of custom spacers for all applications

■

WELLCLEAN II simulator, CemCADE software and WELLCLEAN II advisor engineering tools

■

a testing methodology focused on evaluating the effectiveness of preflushes in removal of drilling fluids

Pipe centralization Because fluids in the annulus tend to flow more freely on the wide side, casing centralization is critical to ensure continuous flow all around the annulus. Schlumberger engineers use the centralization module of CemCADE software to design the optimum degree of standoff to meet the requirements for mud removal.

Services

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Displacement regimes Complete mud removal can be achieved using either laminar or turbulent flow regimes. The choice between the two regimes depends on several parameters and conditions, including well geometry and fluid properties. The design engineer must analyze all the relevant parameters to make the right selection. The WELLCLEAN II simulator is a powerful tool for showing critical results with the chosen fluids and flow regimes. These include such parameters as the percentage of cement coverage, the risk of leaving a mud film or channel at the end of the cement job, and for turbulent flow, the contact time—all as a function of depth and time.

Fluids design Knowledge of cement and spacer fluid properties is essential to ensure proper zonal isolation. The effectiveness of each fluid to displace the fluid ahead of it can be checked using the WELLCLEAN II simulator. Output will clearly predict channeling that exists between the fluids. WELLCLEAN II simulator output guides the design engineer to improve mud displacement through modification of spacer and cement properties and flow parameters.

WELLCLEAN II simulator Ensuring complete zonal isolation is the ultimate goal of cementing operations. However, frequently this goal is not achieved. Because incomplete mud removal is a repeated source of unexpected costs for operators, every effort should be made to ensure critical zonal isolation on the primary cement job. A two-dimensional numerical simulator, the WELLCLEAN II simulator uses computational fluid dynamics to predict the process of cement placement. Based on well geometry and trajectory, downhole fluid properties, volumes, pump rates, and casing centralization, Schlumberger engineers predict the efficiency of mud removal and identify whether a mud channel will be left. Using the WELLCLEAN II simulator, engineers can make the necessary design changes to optimize the operation and achieve zonal isolation. The design engineer uses visually displayed displacement patterns produced by the WELLCLEAN II simulator as a guide to the most efficient and complete form of mud removal.

Applications ■

Mud removal and cement placement to achieve zonal isolation in vertical, extended-reach and horizontal wells


Enhanced zonal isolation Reduced costs associated with mud removal through optimized job design Predictable results validated by physical experiments and field performance


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Accurate rheological description of fluids (Herschel-Bulkley model) Simulation of fluid placement in turbulent and laminar flow Maps of fluid position and concentration in annulus Maps of fluid velocity and flow regime Animated view of fluid displacement process as a function of job time View of potential detrimental contact between mud and cement during displacement


Fluids concentration map

Depth (ft)

Mud risk on the wall

Fluids concentration map

4600

4600

5000

5000

5400

Depth (ft)

5800 6200

Mud risk on the wall

5400 5800 6200

Wide Narrow Wide Wide Narrow Wide

Wide Narrow Wide Wide Narrow Wide

Mud Spacer Cement

High Medium Low None

Modeling allows the engineer to analyze various mud removal scenarios and select the best one to achieve zonal isolation.

WELLCLEAN II advisor The WELLCLEAN II advisor design tool greatly facilitates the selection and adjustment of additive concentrations in spacer fluids for the optimal rheological properties to achieve the ultimate goal of mud displacement and zonal isolation. This software reduces engineering and laboratory time through recommendation of additive concentrations for the specific mud removal scenario (flow regime, required fluid properties) at the temperature of the well.

Chemical washes Chemical washes are used if increased density is not needed for well control and turbulent flow is required. These fluids have a density and viscosity close to those of water or oil. When pumped ahead of the cement slurry, they assist in mud removal by diluting, thinning, and dispersing mud and by water-wetting the casing surface, improving the quality of the bond between the cement and the casing and formation. When oil-base fluid is used for drilling, base oil is often the first preflush fluid and is followed by chemical washes containing surfactants and/or solvents. Schlumberger offers a comprehensive line of MUDCLEAN* chemical washes for all applications.

Table 3-1. Schlumberger Chemical Washes Name

Function

Type Mud Removed

MUDCLEAN WBM

Disperse and thin drilling fluids

WBM

MUDCLEAN OBM

Disperse, thin and invert the emulsion of OBM drilling fluids; water-wet the casing for better bonding

OBM

Services

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Applications ■

Cementing jobs where a light preflush is pumped in turbulent flow

Benefits ■

Improved bonding and hydraulic isolation


Displace mud by thinning, turbulence and erosion Preflushes for any type mud Compatible with cement slurries Compatible with WBM and OBM Leave surfaces water-wet Easy to mix in the field

Chemical washes are lightweight, thin fluids that remove mud by turbulent flow.

MUDPUSH spacers Spacers are weighted fluids that provide a compatible buffer between the drilling fluid and the cement slurry and offer control of rheological and flow properties. They can be designed for turbulent or laminar flow regimes. Performance of the spacer is optimized using engineering tools such as the WELLCLEAN II simulator. Their effective use results in displacement of drilling fluid around and along the annulus for effective zonal isolation.

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MUDPUSH II spacer properties are engineered in the laboratory to optimize mud removal in the field.

To provide effective mud removal, Schlumberger offers a wide range of MUDPUSH* spacer fluids to suit zonal isolation criteria under all well conditions. Schlumberger offers a comprehensive line of MUDCLEAN chemical washes for all applications. Depending on well conditions and on the fluid properties, the spacer is designed to be pumped Table 3-2. Schlumberger Spacers Name

Base Fluid

Density (kg/m3 [lbm/gal])

Flow Regime

Temperature Limit (°C [°F])

Type Mud Removed

MUDPUSH II

Water (up to 20% salt)

1200–2400 [10–20]

Turbulent or laminar

149 [300]

WBM or OBM

MUDPUSH WHT

Water (any salinity)

1560–2400 [13–20]

Laminar

232 [450]

WBM or OBM

in either turbulent or laminar flow. Performance of the spacer is optimized using engineering tools such as the WELLCLEAN II simulator. The MUDPUSH II spacer properties are specially formulated to address environmental concerns. Properties include lower toxicity, better biodegradation and lower bioaccumulation to produce a minimal impact on the environment. MUDPUSH II spacers have less retarding effect on the cement than earlier versions of spacers. Any contaminated cement slurry is subject to less delay in strength development. This proves critical, especially at tops of liners when relatively fast strength development is required. In wells drilled with an oil-base drilling fluid, the proper surfactant and, in some instances, a solvent, are tailored to the base oil. These surfactants and solvents are added to basic MUDPUSH spacer to disperse the oil phase into water and provide a water-wet surface for better bonding to the cement. Services

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Applications ■

All cementing operations to 232°C [450°F]


Turbulent or laminar flow displacement Predictable displacement along the entire cemented interval Good fluid loss control over a wide density and temperature range

Features ■

■ ■ ■ ■ ■ ■ ■ ■

Density range from 1200 to 2400 kg/m3 [10 to 20 lbm/gal] or 1560 to 2400 kg/m3 [13 to 20 lbm/gal] for MUDPUSH WHT spacer Compatible with cement Excellent suspension properties Compatible with fresh water, salt water or seawater Compatible with all drilling fluids (water- and oil-base) Stable rheological profile with increasing temperature Excellent reproducibility between laboratory and field performance Extremely stable Easy to mix in the field

In the upper log, a conventional spacer resulted in poor isolation in the permeable section (140-mm [51⁄2-in.] liner at inclination of 55° with 1800-kg/m3 [15-lbm/gal]) cement. The lower log shows a 178-mm [7-in.] liner in a horizontal well cemented with lightweight cement and using MUDPUSH II spacer for mud removal.

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InterACT wellsite monitoring and control system: Remote real-time data delivery for cementing and pressure testing operations The InterACT* wellsite monitoring and control system provides Web-based data delivery with secure real-time, two-way communication that makes oilfield data and information available anywhere desired by the user. By allowing authorized personnel easy access to project information through an online Internet workspace, the InterACT system promotes teamwork and collaboration in the decisionmaking process. Files of all standard data types and formats can be exchanged, including drilling reports and programs, mud logs and reports, wireline and logging-while-drilling logs, well stimulation data, and surface and subsurface production data. Using this system, engineers can prepare precise, timely cementing designs by gathering data from the historical file of the well. The cementing proposals can then be communicated to all operating company personnel who need the information. Data from wireline logs and well parameters can be easily collected by the design engineer and communicated to others involved in the cementing operation. Data can be easily communicated to laboratory or operations personnel with minimal effort and error-free. Data from many sources, including openhole logs, cementing operations and cement evaluation logs, can be viewed simultaneously. An evaluation based on all the data makes the decision on zonal isolation easier and faster in what is often a critical point in the operation.

Applications ■ ■ ■

■ ■ ■ ■ ■

Remote data transmission Remote monitoring of wellsite operations Two-way communication and distribution of real-time cementing, leakoff test (LOT), formation integrity test (FIT) and completion test information Cement evaluation Remote monitoring and decision-making on squeeze cementing Sharing of data among selected parties Supervisory control of remote assets Distribution of cementing laboratory reports


■ ■ ■ ■ ■ ■

Services

Secure connection to confidential data Real-time worldwide access to data through the Internet or an intranet Speedy communication of well data such as caliper and survey information for cementing design Simultaneous review of data from many sources for cement evaluation Real-time decision-making Promotion of teamwork and collaboration Real-time access to Schlumberger experts Time and expense of travel to wellsite saved Fewer safety and environmental hazards

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Features ■ ■ ■ ■ ■ ■ ■

■ ■ ■

No communication infrastructure or specialized software required Alarm notification services Access to complete well data for use in cementing design User-defined acquisition of data, either streamed or polled Compatible with CemCADE cementing design and evaluation software Comparison of actual job with design Proprietary software for autorecovery and compression to manage network outages and expensive bandwidth Customizable graphics Configurable levels of accessibility for partners and third parties Acceptance and display of wellsite information transfer specification (WITS) or WITS markup language (WITSML) data from any source

The InterACT system allows user to select preprogrammed graphics or customize graphics to display data of interest.

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Personnel participating in an operation, whether it be cementing or testing, can easily view the data during the operation. Users analyze real-time graphical or digital data that are easily uploaded to the InterACT Web site by the wellsite engineer. By viewing the data remotely, personnel at different locations can participate in the operation without the time and expense of traveling to the wellsite. Remote observers can provide responses and instructions throughout an operation. By allowing teams to participate, better decisions can be made in real time, resulting in a more efficient operation. Because it works through the Internet or intranet using a standard Web browser, the InterACT system is inherently easy to use. Data can be viewed from a variety of computers or handheld PCs; data files can also be produced for import to other local applications for further manipulation and interpretation. Numeric displays ensure access to real-time data, even if users are accessing the system over slow connections. Predefined log displays or simple pulldown menu configurations allow users to quickly display data in the desired format, zoom in, change scales and curve attributes, or even switch between scales. Customized displays can be saved and made available to other users. The InterACT system supports common digital formats such as American Standard Code Information Interface (ASCII), Digital Log Interchange Standard (DLIS) and Log ASCII Standard (LAS). The InterACT system also supports all graphical data types, including Picture Description System (PDS) and Tagged Image File Format (TIFF).

System requirements ■ ■ ■ ■ ■

Services

Minimum 200-MHz personal computer 32-MB random access memory Windows NT® Windows® 98, ME, 2000, or XP Netscape® or Microsoft® Internet Explorer browser Internet connection using transmission control protocol/internet protocol (TCP/IP) over local area networks, wide area networks, or modem-to-modem over Ethernet, telephone, cell phone or satellite. There are no restrictions regarding types of Internet access, but a high-speed connection will enhance system performance. A minimal 9600-bps link is required to upload realtime data.

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Software CemCADE cementing design and evaluation software Cementing in today’s challenging wells is a complex task. Wells may have depleted intervals, resulting in narrow windows between pore and fracturing pressures. Deviations can make casing standoff by centralizers hard to determine. Mud removal may be difficult as a result of the standoff and exotic drilling fluids. CemCADE software provides tools to assist the engineer in evaluating all the parameters and in designing cementing slurries and procedures to cement the well and achieve the required zonal isolation. The software is used for all types of wells and casings, from land to offshore in deepwater and from large-diameter conductor casing to the deepest production liner. Tools assist in calculation of centralizer placement, pump rates and spacer properties to achieve mud removal and cement placement; calculation of densities and pumping parameters help maintain well control. Additional tools evaluate the risk of gas migration and allow the engineer to select appropriate solutions to minimize this risk. A module assists engineers in designing plugs to minimize contamination during placement, resulting in much higher plug-setting success. A simulator aids in determining the temperatures to expect during cementing, providing better data for cement slurry design and better schedules for thickening-time tests and compressive-strength tests to determine optimum WOC. A key use of CemCADE software is the optimization of the mud removal process for effective mud displacement and zonal isolation using WELLCLEAN* mud removal technology. This optimization requires knowledge of the stresses placed on the mud by displacing fluids. These stresses, which contribute to displacement of the mud, depend on fluid densities, viscosities, flow regimes and fluid velocities. An additional factor is the degree of casing standoff in the open hole, which has a large effect on localized fluid velocity and flow regime. CemCADE software provides tools that integrate the standoff calculation, the fluid properties, the pump rate and the U-tube phenomenon to assess the ability of a combination of fluid properties and flow rates to achieve the mud removal required for zonal isolation. A proprietary placement simulator, WELLCLEAN II software, assists the engineer in evaluating the potential effectiveness of mud removal by the chosen fluids.

Applications ■ ■ ■ ■ ■ ■ ■ ■ ■

Primary cementing on land and offshore wells Centralizer selection and centralization optimization Mud removal optimization Gas migration risk assessment and optimization Temperature simulations Preparation of cement slurry testing schedules Foamed cement design Postjob analysis Plug cementing


■

Software

29

Benefits ■ ■ ■ ■ ■ ■

Optimized design for effective zonal isolation Well security and control Minimized risk of annular gas migration Optimized plug design Postjob analysis for continuous improvement Real-time comparison of treatment parameter plots with design plots

Features The fluid placement simulator evaluates well control and pipe integrity by computing and comparing hydrostatic and dynamic pressures with the formation fracture and pore pressures, and tubular burst and collapse ratings. This is done for all points in the well during the cementing process. ■ ■

■ ■

■

■ ■

■

■

■ ■ ■ ■

■

■ ■ ■ ■

30

Fluid test data (e.g., rheology and thickening time) are managed in a database. Standoff is optimized using caliper and directional survey data and properties of the centralizers. Forces to run the casing in the hole are calculated. WELLCLEAN technology and fluid-fluid displacement theory is used to predict mud removal and help ensure zonal isolation. Temperatures in the well during conditioning and cementing are determined, enabling slurry design for specific conditions. Schedules for thickening-time tests are constructed using temperature simulator. Temperature schedules are generated to avoid premature setting or excessive WOC time resulting from over-retardation. Postplacement analysis aids in analysis and minimization of the risk of gas migration after cement placement. Postplacement analysis aids in selection of operational procedures and slurry properties for minimization of risk of gas migration. Surge and swab calculations check well security during running and moving casing. Tables are generated to schedule and monitor foamed cement job. Foamed cement job optimization. Well data and cementing parameters are exported to external software, such as SoniCalc acoustic log calculator. Postjob evaluation is performed using quality assurance and quality control plots from data recorded during the treatment. Pressure signature evaluation of unanticipated events. Designs for balanced plug minimize chance of contamination during placement. Volumes for balanced fluids are calculated. Well control and pipe integrity are checked during forward or reverse circulation following plug cementing.


CemCADE simulator computes well security and control pressures experienced for all depths during the cementing process.

Temperature plots show a profile of the temperature in the casing and in the annulus at selected times during the cementing process.

Software

31

Stress analysis model Wells are exposed to many changing conditions that create mechanical stresses on the casing and the cement sheath behind it. These stresses can come from pressure changes; fluid weight changes during drilling and completion; pressure testing and pressure treating such as squeeze cementing or high-pressure stimulation treatments; changes in well pressures caused by reservoir pressure depletion. Temperature changes, especially in upper portions of a well producing high-temperature fluids, can also generate mechanical stresses. FlexSTONE cement is designed to prevent cement failure caused by these mechanical stresses. This flexible and expansive cement can survive the mechanical stresses and maintain isolation in the wellbore, when properly designed. A proper design requires knowledge of the current stress conditions in the well as well as the future conditions that will occur over its life. Stress analysis model software was developed by Schlumberger to predict the stresses to be experienced by the cement sheath throughout the life of the well. By analyzing the changing conditions of the well, the mechanical stresses are determined. The software also assesses the mechanical properties of the cement to determine if the cement will survive these stresses. If not, the mechanical properties of the cement can be modified so that the cement will survive to provide isolation for the life of the well.

Using stress analysis model software, set-cement properties are matched to formation properties and future well conditions.

Mechanical properties of FlexSTONE cement are adjusted through static testing.

FlexSTONE design process.

32


Applications ■

Any primary cementing application

Benefits ■ ■

Isolation for the life of the well Cement designed for the conditions of the well

Features ■ ■ ■

Evaluates well stresses based on anticipated well operations Evaluates cement behavior under anticipated stresses Allows selection of minimum cement mechanical properties to maintain isolation

i-Handbook oilfield data handbook Oilfield-related engineering calculations are dependent on well and treatment-specific information, such as details on well tubulars, hardware, well or equipment on site. During any well operation, the on-location supervisors are required to make many decisions as conditions change. Accurate information is critical to the evaluation of the situation, and real-time calculations of volumes, pressures or rates are often required. Prior to development of the i-Handbook* oilfield data handbook, engineering data were only available in physical handbooks or in a static electronic format. Taking a different approach, the i-Handbook tool is interactive, providing not only the data lookup features of previous products but also simple-to-use calculators for commonly used computations, such as tubular or tank volumes, cementing load quantities, and hydrostatics.

Applications ■ ■ ■ ■ ■ ■ ■ ■ ■

Pipe and cementing data lookup Cementing computations Typical fracturing calculations Coiled tubing calculations Basic materials formulation (cement, hydrochloric acid, brines) Volume calculations for tanks, pits, tubing and annulus Engineering calculations Unit conversions in multiple standards Field quality checks

Benefits ■ ■ ■ ■ ■ ■ ■

Software

Faster, more consistent computations through user-friendly calculators Fewer calculation errors Intuitive extrapolation of computations from single-point entry Faster, more accurate volume calculation for intricate geometries and hanger scenarios Rapid access to database Better understanding of forces through enhanced graphics and animations Archiving of data and calculations for future use

33


■ ■ ■

■

Pipe data for both API standard and non-API tubulars Exchange of data among users Useful calculators to assist in multiple well operations such as drilling and workover, cementing, fracturing, acid, oil and brines and coiled tubing Library of predefined wellbore diagrams Engineering data with source equations Data from tables can be copied and pasted into other applications such as spreadsheets or word processing software View of page can be copied into other applications to use in reports or presentations

The Schlumberger i-Handbook tool retains the familiar appearance of a book, making use of the program intuitive. A right click on the section tab displays a table of contents for the section. Clicking on an item in the list opens that part of the book. Standard oilfield and metric units are supported, and changing the units is as simple as clicking on the displayed unit and selecting the alternate. Users can also save a particular units format under the custom units option, thus having the flexibility of using multiple units systems. Tubing and casing data tables can be expanded so that additional physical properties may be viewed. Data entered in any calculator or wellbore configuration can be saved and sent to another user, thus facilitating quick and accurate exchange of information.

34


Information and calculations unavailable in printed handbooks can be found in the i-Handbook tool. These include tubular data supplied by the vendors and several calculators for common fracturing and cementing computations. Presentation of comprehensive engineering data, complete with source equations, and rapid interactive calculations offer substantial time savings throughout a project. For drilling and workover operations, pipe stretch, free point and critical buckling forces can be calculated by the i-Handbook tool. Typical cementing calculations include slurry formulation, volumes and properties of cement slurries, bulk plant load quantities, displacement volumes, balanced plug volumes, and pressures to land the plug and casing lift forces. For fracturing operations, calculations can be made for slurry density and proppant fill, proppant gate settings for blenders, proppant settling, screenout, sand plugs, and pressure drop. Acid density and dilution tables, API density, and hydrostatic pressures for oils and brine density requirements can be calculated. Ovality of coiled tubing can be calculated as well. For general use, units conversions can be made, and hydrostatic pressures and gradients and volumes in tanks (strap conversions) can be calculated. The i-Handbook tool’s interactive wellbore diagram enables the user to build a graphical view of the wellbore by dragging and dropping data from the tubular tables. After drawing the wellbore, the user can define various flow paths in the well and the volumes of defined sections will automatically be calculated and displayed on the diagram. Configurations can be saved and modified as conditions change during the operation.

Wellbore diagrams can be created by dragging and dropping the elements, and the i-Handbook tool automatically calculates volumes.

Software

35

A thorough understanding of the treatment and effects of recommended actions are communicated through visual, sometimes animated, schematics. Using various input, the user can prepare diagrams illustrating the various combinations of strings and sizes, thus creating multiple realistic design options in one session. With a zoom feature, wellbore features can be examined closely. Wellbore elements are automatically labeled, and the user can color code volumes pertaining to different sections in the wellbore. The completed wellbore schematic can be presented as a picture file pasted in a report by using “copy” feature. In addition to providing views of various fluid positions during the job, the i-Handbook tool can be used to generate configurations corresponding to hangers and wellbore geometries associated with washouts and under-reaming. An automated check corrects elements of the well scenario or alerts the user to an inconsistency so that corrections can be made. For example, the system issues an alert if the input for the outer diameter of a pipe is greater than the wellbore diameter. The i-Handbook tool includes data not included in printed versions of the engineering handbook and each section has been updated with new content. Supplier databases have also been updated and expanded. New offerings include the following.

General (pipe, tubing, casing, tanks) ■

■ ■ ■ ■ ■ ■ ■ ■

Enhanced casing and tubing database with a wide range of pipe diameters and with mechanical properties Drillpipe, drill collar and coiled tubing database Calculator to compute effects of axial loading on collapse pressure Connection interchange list for various thread types Enhanced list of drill bits and clearance Stretch and free-point tables Buckling force calculations for deviated wells Visual and tabular data on tanks of various geometries Visual and tabular information on flange and ring specifications

Volume ■ ■

Annulus and tubular volume calculation Volume-to-depth conversions

Fracturing ■ ■ ■ ■ ■ ■ ■

36

Expanded proppant database Slurry density tables and proppant fill tables Calculation of gate settings for various blender types Proppant settling rates in various fluid types Calculation of flow of gas through chokes Calculation of pressure drop across an orifice Calculation of perforation friction


Cement ■ ■ ■ ■ ■ ■ ■

Quick estimation of borehole circulating temperatures Official Schlumberger cementing materials database Calculations for preparation of cement slurry Bulk-plant loading quantities for cementing materials Calculations for balanced plug Pressure to land plug Casing lift calculation

Acid, oil, brines ■ ■ ■ ■ ■ ■

Brine formulation by percent weight or density Calculator for computing salt requirements for various types of brine Calculator for densities and dilutions of hydrochloric acid Calculator for API gravity of oils Calculation of hydrostatic pressure and gradient based on fluid density Calculation of buoyancy factor

The i-Handbook tool makes it easy to calculate volumes for a balanced cement plug.

Software

37

Materials Introduction In today’s remote areas and extreme environments, exploration puts increasing demands on the technology required for developing new reserves. No new technology is better tailored to these demands than Advanced Cement Technology from Schlumberger. Incorporating 10 years of R&D, Advanced Cement Technology provides a range of cement alternatives, tailored to the well, to achieve zonal isolation for the life of the well. CemCRETE Advanced Cement Technology decouples set-cement properties from slurry density. With CemCRETE systems, properties such as permeability and strength are superior to those of conventional cements. Slurries can be lighter (or heavier) than ever, without compromising properties of the set cement. CemSTONE systems, the newest generation of Schlumberger Advanced Cement Technology, offer set-cement properties that can be adjusted to meet the requirements of the well. They are purpose-built to withstand mechanical stresses and changes in temperature and pressure that damage conventional cements. CemSTONE systems offer control over properties never possible with conventional oilwell cement, allowing you to meet your requirements for such set properties as flexibility, expansion and impact resistance.

Standard cement slurries require water to fill the void between particles. CemCRETE slurries fill the interparticle void with more solids, giving superior cement properties.


■

Materials

39

CemCRETE concrete-based oilwell cementing technology CemCRETE slurries are systems that allow deeper casing points, better high-pressure, hightemperature (HPHT) wells or reduced time WOC in deepwater. Special formulations enable repair in wells where microcements are ineffective. CemCRETE slurries are available in different formulations for various applications. LiteCRETE* slurry systems provide the high strength and low permeability, even at densities as low as 900 kg/m3 [7.5 lbm/gal], necessary to cement across weak formations. DeepCRETE slurries let you cement shallow, weak zones in wells drilled in deepwater, minimize the risk of shallow water flow and return to drilling in a short time. DensCRETE* technology gives you very high-density cements (to 2880 kg/m3 [24 lbm/gal]), for well control with low viscosity. SqueezeCRETE* remedial cementing slurries are specifically designed to solve problems by penetrating narrow gaps more efficiently, without bridging or dehydrating during placement. CemCRETE Advanced Cement Technology is a high-performance alternative to conventional oilwell cement slurries that changes the fundamental rules for cementing. Casing strings can be set deeper without worrying about lost returns. Cements in HPHT wells can be placed at lower circulating pressures and higher rates. Channels and failures in primary cement too small for repair using microcement slurries can be repaired. CemCRETE slurries produce new answers for today’s tough problems, providing zonal isolation for the life of the well. Unfortunately, in conventional cementing slurries, the amount of water needed for mixing and pumping is much more than is optimum for set cement. CemCRETE technology disconnects these two phases of cement performance to give both optimum slurry properties and excellent set-cement performance. CemCRETE technology increases the solids content of the slurry by using engineered particlesize distribution. Smaller particles fill the void space between larger ones, resulting in a slurry requiring less water, yet retaining good fluid properties. Putting more solids into your cement provides greater compressive strength, reduces cement permeability and increases resistance to corrosive fluids. Choosing solids with different properties allows slurry designs to meet the requirements of the application. CemCRETE designs mean cements for production casing can be lower density while maintaining optimum properties for isolation. You can set lighter, longer cement columns. Casing points can be deeper. The set cement performs better than standard cement for the life of the well. In remedial operations, increasing solids content improves the penetrating ability of the slurry and decreases placement pressures.

0.25 0.20 0.15 Permeability (mD)

0.10 0.05 0.00 12.0 lbm/gal 12.0 lbm/gal 15.8 lbm/gal 17.5 lbm/gal Conventional LiteCRETE Conventional DensCRETE cement cement cement cement

Properties of CemCRETE cements are superior to those of cement made using conventional technology. 40


LiteCRETE low-density slurry system When cementing across weak formations, it can be difficult to place sufficient cement behind the casing without using extended, low-density cement slurries or multiple-stage cementing operations. A simple, low-density slurry that performs like conventional-density cements can eliminate these restrictions and allow you to set casing deeper or perhaps eliminate a casing string. The new LiteCRETE high-performance system enables you to redesign your casing program. LiteCRETE technology, a member of CemCRETE Advanced Cement Technology family, provides production-quality cement properties at extended-slurry densities. LiteCRETE slurries can be mixed from 900 to 1560 kg/m3 [7.5 to 13 lbm/gal] for effective placement across weak zones. Once set, these cements provide compressive strength and permeability that are superior to properties of other lightweight systems and even comparable to those of 1900-kg/m3 [15.8lbm/gal] cement.

Foamed cement LiteCRETE cement 3500 3000 2500 Compressive strength (psi)

2000 1500 1000 500 0 8

9

10

11

12

13

12

13

Density (lbm/gal) 3 2 1 Permeability (log mD)

0 –1 –2 –3 –4 8

9

10

11

Density (lbm/gal) Strength and permeability of LiteCRETE slurries are superior to properties produced by foamed cement.

Materials

41

Low-density LiteCRETE slurry frequently eliminates stage cementing in long intervals. With performance similar to higher-density slurries, you can get exceptional perforation quality without reducing cement integrity. LiteCRETE systems are even strong enough for hydraulic fracturing treatments or setting kickoff plugs. In some cases, special properties may be built into CemCRETE slurry systems to meet specific performance criteria. For instance, casing strings through permafrost zones must be cemented with slurries having protection from freezing. For this application, Schlumberger developed Arctic LiteCRETE cement.

Applications ■ ■ ■ ■ ■ ■

Across weak formations where high-performance cement is required Slurries with densities as low as 900 kg/m3 [7.5 lbm/gal] Alternative to stage cementing or topping out Alternative to foamed cement Across completion intervals Kickoff plugs


Production-quality zonal isolation across easily fractured formations Longer cement columns without losses caused by hydrostatic pressure Elimination of two-stage cementing Less damage to completion intervals resulting from slurry or filtrate invasion Whipstock plugs at lower densities with less tendency for contamination or falling downhole


42

Cement with low density but that has completion-quality properties Slurry preparation without special equipment or additional personnel Set-cement properties vastly superior to those of other lightweight systems at equivalent densities


DeepCRETE deepwater cementing solution DeepCRETE slurries let you cement weak zones in deepwater wells, minimize risk of shallowwater flow and return to drilling in a short time. Drilling in deepwater environments means higher costs. Weak formations can fail under the hydrostatic load of the cement column, causing incomplete zonal coverage, additional delay and more expense. Slow-setting cement can allow flow of shallow water or gas, risking the integrity of the well and potentially the surface location. Low BHT can delay compressive strength development, increasing WOC time. When cementing operations are completed, every minute spent WOC costs money. DeepCRETE technology is a combination of efficient technologies for cementing in the difficult deepwater scenario where the temperature is low and shallow flows may exist. It is a part of the Schlumberger deepwater drilling solution. The DeepCRETE solution isolates the formation with a lightweight cement slurry (1200–1650 kg/m3, 10–14 lbm/gal) that develops strength faster than conventional cement systems without requiring special equipment or personnel. DeepCEM additives, which facilitate rapid strength development in the low temperatures, are combined with CemCRETE technology to form a highly effective system that provides the short transition time, early strength development and good fluid-loss control necessary to cement the surface and conductor casing in deepwater wells with risk of shallow flow. The lighter weight allows placement across weak formations. DeepCRETE systems, with a lower heat of hydration, are the right choice in areas where gas hydrates are a concern. DeepCRETE cement is less permeable than conventional cements and therefore protects the casing from corrosive brines. DeepCRETE systems mixed at 1500 kg/m3 [12.5 lbm/gal] develop sufficient compressive strength to return to drilling in less than 24 hr even at 4°C [40°F]. When combined with Schlumberger gas migration technology, DeepCRETE systems provide the right solution for shallow water or gas-flow problems.

Applications ■

■

Placement of full columns of cement for complete coverage across weak, shallow formations in deepwater Potential shallow water or gas flows


Cement circulation to surface across weak shallow formations WOC time minimized in low-temperature environments Control and isolation of shallow water or gas formations Low-density, low-temperature cementing without complicated equipment setup or additional personnel on the rig


Materials

Rapid compressive strength development even at 4°C [40°F] Low density with compressive strengths comparable to those of higher-density cement Low density with low permeability Slurry preparation without special equipment or additional personnel Compatible with Schlumberger gas migration technology

43

3500 DeepCRETE at 12.5 lbm/gal Class G at 15.8 lbm/gal

3000 2500 2000 Pressure (psi)

At 65°F

1500 1000 500 0 0

5

10

15

20

25

30

Time (hr) At low temperatures, 1500-kg/m3 [12.5-lbm/gal] Deep CRETE slurry develops strength faster than conventional Class G cement with density of 1895 kg/m3 [15.8 lbm/gal]. WOC time is reduced, saving rig time and reducing costs.

DensCRETE Advanced Cement Technology When working on HPHT wells, the fewer unplanned concerns there are, the smoother the operation runs. An ideal cement system offers a simple robust design, lower viscosity and the versatility of slurry density that can be easily increased on location. Using unique engineered-particle-size technology, DensCRETE systems give you very highdensity cements, up to 2880 kg/m3 [24 lbm/gal], with low viscosity. Because of higher compressive strength and lower permeability, DensCRETE slurries outperform conventional high-density slurries to provide high-pressure zonal isolation for the life of your well. The primary applications for DensCRETE technology include high-pressure primary cementing, well control plugging, whipstock or kickoff plugging, and grouting operations.

500 450

Conventional cement DensCRETE cement

400 350 300 Friction pressure (lbf/1000 ft)

250 200 150 100 50 0 1

3

5 7 Pump rate (bbl/min)

9

CemCRETE technology results in slurry formulations that have excellent flow properties. Friction pressures are much reduced, so slurries can be placed at greater flow rates to reduce placement time and enable better mud removal. 44


High-pressure drilling can require sudden changes in mud weight. With DensCRETE technology, you can quickly increase the slurry density by 120 kg/m3 [1 lbm/gal] on location. With reduced risks, shorter placement times and lower costs, DensCRETE systems offer the highdensity cementing alternative with higher performance.

Applications ■ ■ ■ ■ ■

High-pressure primary cementing High-density slurries to 2880 kg/m3 [24 lbm/gal] Well control plugs Sidetrack and whipstock plugs Grouting


Easier slurry placement in narrow fracture-pressure/pore-pressure windows Reduced costs and risks associated with long WOC High-density cements that can be continuously mixed


■ ■ ■ ■

High-density cement slurry with lower viscosities Greater density differentials with high-density drilling fluids Shorter placement times, allowing use of slurries with shorter pumping time, and consequently shorter WOC time Stability at high temperatures without special additives Easy design of high-density systems Reduced additive requirements Ability to increase the density at the wellsite using special additives

SqueezeCRETE remedial cementing solutions Oil and gas wells, old or new, can develop isolation problems that normal cements or even microcement cannot repair. Microannuli, leaking liners and old perforations are just some of the problems that may remain even after multiple cement squeeze attempts. SqueezeCRETE technology is specifically designed to solve these problems by enabling more efficient slurry penetration into narrow gaps without bridging or dehydrating during placement. It even penetrates farther and more efficiently than microcement. In laboratory testing, SqueezeCRETE slurry has been injected into gaps as small as 120 micrometers [0.005-in.]. SqueezeCRETE slurry develops more than 13.8-MPa [2000-psi] compressive strength and extremely low permeability. This system can seal liner tops, microannuli or other areas where primary isolation has failed. SqueezeCRETE systems are resistant to acid and corrosive brine, allowing the cement to seal old perforations even when future acid stimulations are planned. SqueezeCRETE systems can be prepared using conventional cementing equipment.

Materials

45

Syringe containing the slurry to be injected

Transparent plate Filter paper

Spacer medium, delimiting a “channel” Porous plate

Injection point

Well-dispersed microcement slurry

Injection point

SqueezeCRETE slurry

In this 120-micrometer [0.005-in.] slot test, well-dispersed microcement bridged immediately after entering the slot. SqueezeCRETE slurry penetrated and filled the entire length of the slot, providing a complete, effective seal.


Microannulus repair Repair of leaking liner tops Repair of leaking perforations Squeeze of small channels Plugging and sealing of old gravel packs


Improved penetration into difficult-to-repair and difficult primary isolation problems Superior channel-filling properties for complete isolation repair Low placement pressures for improved fluid placement Restoration of zonal isolation or well integrity


46

Superior injectivity compared to other remedial systems, including microcements Superior slurry properties, including low viscosity, low fluid loss Superior set-cement properties, including high compressive strength and low permeability


CemSTONE Advanced Cement Technology CemSTONE systems provide reliable, long-term zonal isolation despite changing downhole conditions. These systems control set-cement properties, such as flexibility, expansion and impact resistance, so the cement can withstand stresses that destroy conventional oilwell cements. The following systems are included in the CemSTONE family. FlexSTONE systems provide mechanical properties that can be adjusted to match the wellbore stresses and provide permanent zonal isolation to seal wellbore fluids behind casing. ThermaSTONE* chemically stabilized cement for ultrahigh-temperature applications combine the patented engineered-particle-size technology with new cement blend chemistry to produce cement having excellent strength, long-term durability, and corrosion resistance in geothermal and steamflood wells. DuraSTONE* Advanced Cement Technology systems are tougher and have better impact resistance than conventional cements, so they are more durable and provide better isolation under rugged drilling and completion conditions. Even when conventional cement is properly placed and initially provides zonal isolation, changes in downhole conditions can induce stresses that cause the cement sheath to lose its integrity. Large increases in wellbore pressure, temperature or tectonic stresses can crack the sheath and can even reduce it to rubble. Radial movement of casing caused by temperature changes, pressure changes or cement bulk expansion can cause the cement to lose its bond to the casing, and bulk shrinkage can cause the cement to lose its bond to the formation. In either case, a microannulus is created. Changes in mud weight during drilling and completion can contribute to these pressure changes. Temperature or pressure changes can also generate tensile stresses that can cause cracking of the cement sheath and loss of zonal isolation. Proprietary additives, combined in proven engineered-particle blends, enable CemSTONE systems to meet specific mechanical property requirements: elasticity, expandability, compressive and tensile strength, durability, and impact resistance. As a result, these systems can withstand downhole stresses for the life of the well, providing long-term wellbore integrity that conventional cement cannot. This long-term integrity reduces remedial cementing costs, ensures isolation for stimulation treatments, and reduces the possibility of annular pressure during a gas well’s producing life. It can also extend the productive life of steam injection wells and wells in tectonically active areas. Durable, impact-resistant systems substantially improve success when setting problematic kickoff plugs, leading to rig time savings and ultimately lower drilling cost. These systems also improve the stability of the cement sheath across other areas subjected to high drilling impacts, such as multilateral junctions. Combined with stress analysis model software, these CemSTONE slurries provide powerful engineered solutions. Engineers can model changes that will occur in the cement sheath over the life of the well and optimize the mechanical properties of the set cement to compensate for these changes. The result is zonal isolation for the life of the well.

Materials

47

Microannuli are created by changing the fluid weight. CemSTONE systems can expand to reseal the well.

Complicated completion techniques such as multilaterals shatter conventional cement. CemSTONE systems provide better durability.

Temperature shock that occurs when hot produced fluids pass through lower-temperature surface casings causes stress cracks in conventional cement. CemSTONE systems are very resistant to thermal and mechanical stresses.

Any changes in wellbore stresses can cause loss of isolation. Stress analysis model software can help optimize design parameters to improve well life.

Modern well construction techniques can destroy conventional cements. CemSTONE systems have superior mechanical properties.

48


FlexSTONE Advanced Cement Technology For years cements were designed based on the optimal properties necessary for slurry placement. The set-cement properties—high compressive strength and low permeability—were assumed to be sufficient for all well conditions. Today, the importance of an isolation material that will last under complicated well stresses is better understood. The set cement must withstand stresses caused by changes in temperature and pressure in the wellbore throughout the well’s life. This reliability is especially relevant considering the expense and difficulty of repairing wells. Changes in pressure caused by production, injection or high-pressure treatments can impose stresses on the cement through the casing. Isolation is always needed across the productive intervals, but it is also needed in other intervals that may protect valuable surface waters or prevent movement of corrosive or hazardous liquid or gas behind the casing. Changes in temperatures resulting from production of high-temperature fluids or injection of hot fluids, such as steam, can expand the casing and create great stresses in the cement sheath. These changes can cause tensile stresses that crack the cement. FlexSTONE Advanced Cement Technology systems offer mechanical properties that can be engineered to meet the changing stresses in the wellbore: lower permeability than conventional cements, good compressive strength, better flexibility and better chemical resistance. With these properties customized to the well, the system will resist stresses and maintain isolation. FlexSTONE systems also expand to seal any microannulus. Because FlexSTONE cements are engineered to be more flexible than the formation they seal, this expansion of the cement sheath occurs both outward (i.e., toward the formation) and inward (i.e., toward the casing), thus assuring complete hydraulic isolation. With FlexSTONE systems, you will have a seal in your well that provides long-term protection from microannuli formation, stress cracks, corrosive fluid invasion, annular gas pressure and fluid migration. As part of the new Advanced Cement Technology solution, FlexSTONE systems offer zonal isolation for the life of the well.


HPHT gas wells Casings subjected to changing stress loading Casings isolating gas, either productive or nuisance Steam injection wells Areas with high tectonic stresses

Benefits ■ ■ ■ ■ ■ ■ ■

Materials

Zonal isolation during and after stimulation treatments Extended productive life of steam injection wells Long-term isolation and casing protection in dynamic stress environments Long-term isolation and casing protection in corrosive environments Protection from annular gas and fluid migration Prevention of sustained casing pressure Prevention and healing of microannuli resulting from decreases in pressure or temperature while drilling and completing

49

12 Conventional cement FlexSTONE system

10 8 Well isolation properties

6 4 2 0 T/E ratio

Bond strength Permeability (MPa after 4 weeks’ set time) (µD)

Properties of conventional cements are not adequate for difficult well isolation. FlexSTONE systems have higher ratios of strength to Young’s modulus (T/E) and higher bond strength while maintaining low permeability.


50

Mixed and pumped with conventional equipment Flexibility adjusted to the requirements for the life of the well Linear expansion two to three times greater than possible with conventional cement systems Lower permeability than conventional cement—independent of slurry density Resistance to corrosive fluids


DuraSTONE Advanced Cement Technology Previously, oilwell cements were designed to be pumped, to develop strength and then to remain relatively undisturbed behind casing, thereby providing isolation and pipe support throughout the production cycle of the well. Mechanical shocks during further drilling or other well operations that can destroy the integrity of the cement sheath were not considered, although they could impair zonal isolation. Modern reservoirs require more complicated technology. Complex drilling programs call for bicentered bits, multilaterals or milled windows, and difficult sidetracks. Completions use larger perforations or higher perforation densities in ever thinner producing intervals. Isolation in these situations is critical; it requires a tougher material with better tolerance to vibration and impact. DuraSTONE Advanced Cement Technology systems are more durable or tougher than conventional systems. DuraSTONE systems have all the desirable properties of production-quality cement, but they survive flexural stress, vibration and impact. With DuraSTONE designs, you can maintain zonal isolation across sections of the well that will be subjected to extreme mechanical impact stresses. Drilling tests have shown DuraSTONE systems to be two to three times tougher than conventional cements; this allows faster kickoff in less distance, even in hard formations. As part of the new Advanced Cement Technology solution, DuraSTONE systems offer zonal isolation for the life of the well.


Multilateral completions Reentry wells Sidetrack plugs, especially in hard formations Across shoes where impacts are high during subsequent drilling

Benefits ■ ■ ■ ■

Zonal isolation integrity across multilateral junctions Improved security against failure of the cement sheath in high-impact areas Better isolation in high-density, precision perforating Improved success in setting sidetrack plugs

Features ■ ■ ■ ■ ■ ■ ■

Materials

Engineered mechanical properties Mixed and pumped with conventional equipment Increased durability High resistance to impact Lower permeability than conventional set cement—independent of slurry density Broad density range (1200–3360 kg/m3 [10–28 lbm/gal]) Greater drilling resistance for faster sidetracks

51

DuraSTONE Advanced Cement Technology systems are more durable and have better impact resistance than conventional cements, so they provide better isolation under rugged drilling and completion conditions. The conventional cement (top right) failed after 6 impacts while the DuraSTONE cement (bottom right) held up to more than 82 impacts.

16 15X 14 12 10 DuraSTONE system performance

8 6 4

3.5X

3X 2

Conventional cement performance

0 Drilling resistance

Impact Energy for resistance flexural failure

DuraSTONE systems are tougher than conventional cement. They have better drilling resistance and impact resistance, and significantly more energy is required to cause flexural failure.

52


Cementing Slurry Systems Portland cements that conform to American Petroleum Institute (API) Specification 10A (ISO 10426-1:2000) are supplied where available or by request. These cements are supplied as Ordinary (O) grade (Classes A and C), Moderate Sulfate Resistant (MSR) grade (Classes B, C, G and H), or High Sulfate Resistant (HSR) grade (Classes B, C, G and H). Sulfate resistance is necessary to protect against attack of the hydrated (set) cement by soluble sulfates. Where several grades exist, local requirements determine the grade that is available.

Lightweight Cements Lightweight cements are used to control losses to weak or high-permeability formations. In most cases, cement extended by the addition of water and additives to prevent water separation are adequate to control the losses. These cements generally have low strength and high permeability. However, when low density with either high strength or low permeability is required, special formulations are necessary to meet those requirements. Applications for lightweight cements include very weak, fractured, and highly permeable or vuggy formations. Such cements can be used in primary, squeeze or plug cementing.

Low-density LiteCRETE cement or foamed cement can float on water. After a short period, the high-porosity foamed cement sinks as a result of water absorption. LiteCRETE cement continues to float as a result of its low porosity and permeability, which is beneficial for preventing gas flow and damage to the cement or casing by corrosive fluids.

Materials

53

LiteCRETE cement

LiteCRETE cement is a special formulation using patented technology to produce very low permeability and high strength. LiteCRETE cement is discussed in detail in the section on CemCRETE cements. D049 lightweight cement

D049, TXI lightweight oilwell cement is a special cement with lightweight components interground to provide an economical low-density, high-yield slurry. Because of the composition, the low specific gravity and the particle size of the grind, slurries can be mixed over a wide density range without extenders. This feature gives high versatility and flexibility to D049 lightweight cement. By varying the mix water-to-cement ratio, slurries can be mixed over a density range of 1440 to 1700 kg/m3 [12.0 to 14.2 lbm/gal] without excessive free fluid or high rheology. Because of the chemical composition and particle size, D049 lightweight cement provides excellent strength. Strengths at low densities are superior to those of conventionally extended cements. In most cases, the strength of D049 lightweight cement is adequate for completion, making a tail slurry unnecessary. Elimination of a separate tail slurry can simplify the cementing operation and improve the quality of the isolation. D049 lightweight cement requires no blending and no special additives. Properties of D049 lightweight cement can be adjusted to meet almost any performance criteria needed to cement a well. Foamed cement

Cement is foamed by adding a gas (generally nitrogen) and surfactants. Foamed cement has been very effective in controlling losses when very weak formations are cemented or where formations are highly permeable. The thixotropic nature, in addition to the low density of the cement, makes it highly effective in these scenarios. In addition to their low density, foamed cement slurries provide excellent strength and relatively low permeability compared with low-density cements prepared by conventional means. Foamed cement has greater durability than conventional cements. This cement can be made at virtually any density, depending on the density of the base slurry and the amount of gas. Virtually any cement used in the oil field can be used as the base slurry. A further advantage of foamed cement is that the density at which it is mixed can be selected immediately prior to the job, unlike the case of preblended cements. Additionally, by merely adjusting the gas ratio, the density can be changed during the job to provide slurries with different properties in different parts of the well.

54


Improved bonding cements FlexSTONE cement—advanced flexible cement technology

FlexSTONE cement systems provide mechanical properties that can be adjusted to match the wellbore stresses. When designed with the assistance of stress analysis model software, flexibility and expansion properties provide permanent zonal isolation to seal wellbore fluids behind casing. See page 48 for details on FlexSTONE cement. WELBOND cement—improved bonding cement system

WELBOND* improved bonding cement systems were developed to improve zonal isolation through better bonding. They improve the cement-to-pipe and cement-to-formation bonds by controlling fluid loss and by adhesion properties provided by latex additives. Furthermore, their low permeability when set prevents fluid movement behind the casing. For optimal bonding properties, the latex concentration is adjusted to control fluid loss below 70 mL/30 min. When bonding is not an issue but fluid-loss control is a necessity, the latex is adjusted to control fluid loss to less than 100 mL/30 min. This formulation provides a costeffective alternative to polymeric fluid-loss agents, particularly at high temperatures. WELBOND slurries can be used over the entire range of temperatures, densities and depths that normally occur in oil and gas wells. SALTBOND cement—cement system for cementing across salt zones

The cementing of wells penetrating massive salt formations poses a number of problems. Frequently, cementing across salt formations makes it necessary to use slurries containing high concentrations of salt. Historically, salt-saturated cement slurries have had technical limitations. Many additives cannot tolerate saline environments or are degraded in the presence of salt. Other additives, which can tolerate the salt, often result in undesirable performance. Effects of the salt and additives used with it have led to poor early strength development, especially when conventional fluid-loss additives were used. The unusually high plasticity of salt causes it to deform, or flow, when it is subjected to stress. Thus, under normal overburden pressures salt zones will typically encroach upon a well drilled through them. The nonuniform nature of this flow results in point-loading on casing strings, often causing their failure and collapse. To reduce this risk it is essential that the cement slurry develops good early compressive strength, thereby preventing the movement of the salt formation into the wellbore. One of the key performance problems in high-salinity cements is obtaining sufficient control of fluid loss. Many polymers do not perform well in high-salinity systems. Thus, standard fluid-loss additives could not provide the level of fluid-loss control needed and drastically increased slurry rheology. Additionally, formulations for cementing through salt greatly delayed strength development, leading to operational delays and exposure to hazards while waiting for the cement to set. SALTBOND* slurries are specially designed for use across salt zones. They use a special additive that provides fluid-loss control and dispersion in salt-rich slurries. API fluid-loss values as low as 40 mL/30 min are obtained as are good rheological characteristics, short controllable thickening times, and good early strength. The normal temperature range over which these slurries can be applied is 49 to 121°C [120 to 250°F] BHCT. SALTBOND slurries contain 18 to 37% (based on the weight of water) salt and exhibit the following properties: ■ fluid loss as low as 40 mL/30 min

Materials

■

very low rheological characteristics

■

short controllable thickening times

■

good early strength development.

55

With a low rate of fluid loss and low rheology values at high salinities, the SALTBOND service also provides controllable thickening times and high early compressive strengths. The result is valuable protection against casing collapse. SALTBOND slurry offers these advantages: ■ good fluid-loss control (less than 100 mL/30 min) ■

low placement (friction) pressures to help prevent loss of circulation

■

high early compressive strength to help prevent casing collapse

■

predictable slurry properties attained with only one additive (and one retarder, if required)

■

good bonding against salt formations

■

no potential dissolution of the salt formation while cementing.

RFC regulated fill-up cement

RFC* regulated fill-up cement slurries are highly thixotropic, forming a rigid gel structure shortly after slurry movement has stopped. They also expand. RFC slurries provide a number of distinct advantages over conventional cement slurries because of their thixotropic and expansive properties. Thixotropy minimizes losses and provides better bonding and zonal isolation through expansion. RFC cement is a mixture of Portland cement and plaster. With minimized losses, RFC slurries provide more predictable fill-up in the well. RFC slurries are advantageous in any application in which it is desirable for the slurry to quickly become immobile after placement. In addition to primary cementing where losses are minimized, these systems can also be used to provide a gelled barrier to prevent further penetration during squeeze cementing, thus improving success of squeeze cementing. An important property of RFC cement is the expansion of the set cement. The plaster reacts with the tricalcium aluminate in Portland cement to provide expansion during the early strength development. This expansion acts to compensate for slight dimensional changes in the pipe resulting from thermal or pressure changes following cement placement. Thus, the expansion helps prevent microannulus development, resulting in improved zonal isolation. SELFSTRESS expanding cement system

SELFSTRESS* expanding cement provides improved bonding. The maximum application temperature is 85°C [185°F] BHST. SELFSTRESS cements can be used where thixotropic properties are undesirable. SELFSTRESS cement is composed of Portland cement, plaster and salt or dispersant, depending on the application. Other additives, such as retarders, fluid-loss agents, dispersants, and extenders may be used as required.

Fast strength development DeepCEM Cement

When cementing at shallow depths below the mudline in deepwater wells, rapid strength development is critical to prevent water flow and to provide adequate strength to continue operations, avoiding costly waiting time. DeepCEM cement additives provide the dispersion needed to minimize adverse gelation effects, minimize friction pressure and to enhance compressive strength development. DeepCEM dispersant D185, unlike most dispersants, does not retard at the very low temperatures encountered at shallow depths below the mudline. This property, coupled with the rapid set-enhancement offered by D186, the DeepCEM set enhancer, provides the rapid strength development needed in this tough cementing environment. DeepCEM set enhancer provides much more rapid strength development than standard accelerators.

56


Slurries formulated with DeepCEM additives are simpler and easier to design than other slurry formulations for deepwater cementing. When used with DeepCRETE Advanced Cement Technology slurries, these benefits are provided in a system that has low density, avoids losses and sets rapidly. This same technology is used in land operations where fast strength development at low temperatures is required. ARCTICSET cement—cement system for use through permafrost

ARCTICSET* cements are designed for low-temperature applications across permafrost zones. They will not freeze but will set and develop adequate strength in wells having temperatures as low as –9°C [15°F]. ARCTICSET cements have low free-water separation, low permeability, excellent durability to temperature cycling, and controllable pumping times and gel strength properties. To ensure that the mix water does not freeze before the cement hydrates, a freeze depressant is used. Heat of hydration is low to prevent thawing of the permafrost. ARCTICSET formulations are available for a variety of wellbore conditions including normal density, lightweight and with lost circulation materials (LCM). Right-angle set cement

At low temperatures, conventional accelerators like calcium chloride often do not provide either early setting or rapid strength development. This is especially true below 20°C [68°F]. Right-angle set cement systems are designed for use at low temperature, between 0°C [32°F] and 30°C [86°F], where short WOC time and/or short transition time are required. Application at temperatures to 122°F [50°C] is possible. Regardless of the temperature, a compressive strength of 500 psi can be obtained 1 to 2 hr after the setting begins, while the slurry transition time from 30 to 100 Bc consistency is only a few minutes. The thickening time can be adjusted easily between half an hour and several hours, without impairing this right-angle setting property. Right-angle set cement is known by several names, depending on the application, including surface-set cement and quick-setting cement.

Materials

57

Cements for harsh environments In some situations, cement with special resistance properties is required. This is true in wells with soluble sulfates that can attack the cement (generally controlled by the chemistry of the Portland cement during manufacture) or when other chemical compounds may contact the cement. Sulfate resistance is imparted to the cement in moderate- and-high-sulfate resistant cements during manufacture. Resistance to attack by other chemicals is controlled by selection of the components added to the cement or by using special cements, such as synthetic cement. Acid-resistant cement

In some situations, cement is exposed to acid. Portland cement is acid soluble, although in most cases acid treatment does not cause failure to the cement sheath. When large volumes of acid are pumped at high rates and expose old perforations that have been sealed with cement, the plugs in the perforations sometimes fail. Acid-resistant cement can prevent such failures. Acid-resistant cement is made from conventional API cement with a special formulation of latex that reduces the permeability of the cement and imparts acid resistance. When used for plugging perforations, this formulation has been effective in wells where acid treatments have caused failure of the plugged perforations in other cement formulations. When complete resistance to attack by acid or other chemicals is required, synthetic cement can be used. Carbon dioxide-resistant cement

Carbon dioxide-resistant cement was developed for completions in wet carbon dioxide environments. Applications include source, injection and production wells in carbon dioxide enhanced oil recovery projects or oil and gas wells with high levels of carbon dioxide. Under these conditions, wet carbon dioxide chemically attacks cement. The end result is a loss of strength and structural integrity in the casing sheath. This cement is 45% more resistant to carbon dioxide leaching than either conventional cement or typical fly ash-cement blends of equivalent density. Although the carbon dioxide corrosion rate is dependent on the amount of water present and is difficult to predict, the use of carbon dioxide-resistant cement translates into improved performance with respect to completion life at approximately the same cost per sack as conventional cement. These systems are applicable in the temperature range of 16 to 93°C [60 to 200°F]. Because of their low permeability, the cements of Advanced Cement Technology, CemCRETE and CemSTONE cements are well-suited for such use, either on their own or supplemented with the special treatments used to prepare the acid-resistant cement or carbon dioxide-resistant cement. Synthetic cement

Synthetic cement is designed for completing waste-disposal wells. It is characterized by high corrosion resistance and high compressive and shear-bond strength. Synthetic cement is resistant to attack by strong acids and bases, such as 37% hydrochloric, 60% sulfuric and 50% sodium hydroxide, at elevated temperatures. However, it is not resistant to organic solvents such as acetone or chlorinated solvents. The system density can be adjusted from 1140 to 1560 kg/m3 [9.5 to 13.0 lbm/gal]. The upper temperature limit of synthetic cement is between 93 and 104°C [200 and 220°F], depending on the required pumping time. Remedial cementing is another application for synthetic cement. Computer modeling shows that it can enter microleaks and microannuli at low differential pressures.

58


UniSLURRY cement systems The UniSLURRY cement system concept is a new methodology for designing cement slurries in which the additives use chemistry designed to perform specific functions. Because they are builtfor-purpose, they are highly effective and have minimal effects on properties other than those for which they are intended. Only a few universal additives are required to work in the entire range of well conditions, from conductor casing to production liner. Additionally, UniSLURRY additives work together synergistically. These features improve the entire cementing process, from prejob laboratory testing to execution in the field. The innovative, superior chemistry common to all UniSLURRY additives provides technical and economical advantages, such as reduced additive consumption and shorter WOC times. Prejob laboratory testing is shorter and more efficient because a few reliable and predictable UniSLURRY additives have taken the place of many less-efficient additives. Stocking of materials at the warehouse and on location is more efficient because fewer additives are needed to complete all cement jobs. Mixing on location is improved because smaller quantities of additives are required. UniSLURRY systems can be used for all cementing operations, including casings, liners, plugs and squeeze jobs. The UniSLURRY concept can be used over a wide temperature and density range, addressing most oilfield cementing requirements. The UniSLURRY family consists of four members: UNIFLAC* S solid and UNIFLAC L liquid unified fluid-loss additives and UNISET* LT and UNISET HT liquid unified retarders. These versatile, unified additives cover all cementing conditions and bring to everyday cementing operations a quality previously found only in highly technical areas such as deepwater or HPHT wells. Their versatility simplifies the logistics of cementing operations by reducing the number and quantity of additives that have to be transported and stored at the wellsite. The environmentally friendly UniSLURRY products are used for both land and offshore operations. They are the first choice when logistics are an issue; e.g., on offshore or remote locations. Conventional cementing additives have addressed a particular range of temperature and set of conditions, such as maximum water salinity or cement type, making them highly specialized. This specialization has made the design of cement slurries both time-consuming and complicated. The UniSLURRY products perform over a broader range of temperatures and salt concentrations and work in any application; cementing casing or liner, squeeze or plug. Their performance is consistent and practically independent of the cement type or brand. UNIFLAC additives and UNISET additives work synergistically, allowing reduction of additive concentration while maintaining slurry quality. The benefits of the UniSLURRY additives extend to every aspect of the cementing operation: ■ Laboratory testing—UniSLURRY additives make the laboratory-testing process more efficient. Consistent and predictable, the UniSLURRY additives work with simpler and more reliable designs (both UNIFLAC additives and UNISET additives exhibit nearly linear dependence on temperature and other parameters). ■ Logistics—When cementing with traditional additives, the temperature limitations often make it necessary to use different sets of additives on different strings of pipe. This makes it necessary to stock numerous additives, both at the warehouse and at the wellsite. Because UniSLURRY additives can be used on all casings from conductor to liner, surplus additives from one job can be used on the next cementing job. Unnecessary handling between jobs is avoided, precious space on the rig is conserved, and waste is reduced, thus reducing the overall cost and enhancing operational safety and efficiency. ■ Job execution—UniSLURRY technology simplifies cement job execution at the wellsite. Fewer additives are required to obtain the needed slurry properties. This benefit simplifies the mixing operation, especially in remote locations using liquid additives. All UniSLURRY additives share some common benefits and features.

Materials

59


Simplified slurry design Cost-effective Minimized rig time Fewer additives for simplified wellsite logistics Low sensitivity to cement variations for reduced slurry-design time

Features ■ ■ ■ ■ ■ ■ ■

Universal fluid-loss and retarder additives for any condition Low sensitivity to cement brands Low sensitivity to temperature and concentration variations Lower concentrations needed Highly predictable concentration and thickening time Minimized WOC time Environmentally friendly chemistry

UNIFLAC unified fluid-loss additive for cement Inadequate fluid-loss control can lead to serious problems during cementing operations. Loss of fluid from the cement slurry can result in friction pressure increases, shorten thickening time and increase the risk of microannulus and loss of zonal isolation. UNIFLAC additive is a universal and cost-effective solution for fluid-loss control in all cementing applications. The additive is a custom-made, third-generation polymer that is available in liquid (D168) or solid (D167) form. The solid additive can be dry-blended with the cement or predissolved in the mix water. Its robust properties make slurry design very simple and produce predictable results in the field, from the conductor casing to the liners. Test results demonstrate the very low sensitivity of UNIFLAC additive to variations in temperature or concentration. It also has a low sensitivity to cement brands. The same additive is used at all temperatures, from 10 to 260°C [50 to 500°F]. Synergy between UNIFLAC additive and Schlumberger UNISET retarders provides additional operational benefits. When used with UNIFLAC additive, the concentration of UNISET retarder required to achieve a desired thickening time is reduced and early compressive strength development reduces WOC time.

0.9 0.8 0.7 0.6 UNIFLAC L (gal/sk)

0.5 0.4 0.3 0.2 13.0 lbm/gal 16.2 lbm/gal 18.5 lbm/gal

0.1 0.0 50

150

250 Temperature (°F)

350

450

UNIFLAC L additive concentration to achieve API fluid loss of 50 mL/30 min is easily predictable at different temperatures and slurry densities. 60



All cementing applications Wells with temperatures from 10 to 260°C [50 to 500°F]


Economical Savings from less WOC time Simplified slurry design Simplified logistics—few additives required

Features ■ ■ ■ ■ ■ ■ ■ ■

Low sensitivity to cement brands Low sensitivity to temperature All densities Fresh to salt-saturated mix water Compatible with all additives, including calcium chloride accelerator and silicate extenders Synergy with Schlumberger UNISET retarders Low concentration requirements Excellent slurry rheology

UNISET set control additives Schlumberger UNISET set control additives provide a unique set of properties that are not available with conventional retarders. Cement retarded using UNISET additives exhibits a rapid setting behavior, even with longer thickening times for increased safety factors. Their synergistic behavior with UNIFLAC additives allows lower concentrations (as much as two-thirds reduction), thus improving economics.

12 10 D177 and D168

8 Thickening time (hr)

6 D177

4 2 0.00

0.05

0.10

0.15

0.20

0.25

Concentration (gal/sk)

Use of UNISET retarder with UNIFLAC additive results in synergy that allows much reduced concentrations.

Materials

61

Excessive retardation by conventional retarders impairs strength development, extending WOC time and making the cement vulnerable to invasion by well fluids or mechanical damage from changing stresses in the well. In extreme cases, some cementing treatments must be done in several stages to avoid excessively long setting times. This complicates and increases the overall cost of the operation. UNISET HT additive retards to provide sufficient time to place the cement, yet promotes early and rapid strength development to minimize WOC time. UNISET HT additive is also much less sensitive to temperature variations than other cement retarders. It is the preferred retarder for the most challenging situations when temperature is not well defined or if there is a large difference between temperature at the top of the liner and the bottom of the cement.

Applications ■

All cementing operations


Simplified slurry design Much reduced risk of problems from inherent temperature errors Cost benefits from simplified logistics, reduced additive usage and shorter WOC time Lower concentrations required due to synergy with UNIFLAC additives

Features ■ ■ ■ ■ ■ ■ ■

Full range of temperature All densities Fresh water and seawater Highly reliable and predictable concentration and thickening time response Only two additives needed for entire temperature range Synergistic with UNIFLAC fluid-loss additives Rapid setting and compressive-strength development

7 16-lbm/gal slurry

6 5 D121/D28

Ratio of time to reach 50 psi at 320°F (hr) to thickening time at 350°F (hr)

4 3 D121/D28

2 1 2

4

6

8

10

12

Thickening time at 350°F (hr) When UNISET HT additive is used, extended thickening times do not result in the excessive WOC times found with conventional retarders.

62


UNISET additives are available for low- to moderate-temperature and high-temperature applications. UNISET LT additive covers applications to about 120°C [250°F], and UNISET HT additive can be used from about 80 to 260°C [180 to 500°F]. UNISET retarders are compatible with most other Schlumberger cementing additives.

1.0 0.8 0.6 Concentration (gal/sk)

0.4 0.2 0.0 180

200

220

240 260 Pump rate (bbl/min)

280

300

320

The relationship between concentration and temperature is linear, making concentration selection simple when using UNISET HT retarder. The graph shows the concentration required for a thickening time of 4 to 5 hr.

Cementing additives The following paragraphs and tables describe the performance of cementing additives by functional group. Some materials are discussed in more detail in sections on specific functional systems. The Cementing Additive Quick Guide and Cementing Additive List provide descriptions of additives listed by functional group and by code, respectively. The list gives general application conditions for each additive. These application conditions reflect those tested during product development. In many cases, the products can be used outside the quoted conditions with testing appropriate to specific applications.

Accelerators Accelerators are materials that cause cement to hydrate and develop strength earlier and faster. They are commonly used to provide improved strength at low temperatures and to counteract the retarding effects of other additives. Accelerators also shorten the thickening time.

Antifoam and defoam agents Antifoam agents prevent or reduce the foaming tendencies of cement when it is mixed. This is necessary because the properties of cement slurries and the set cement depend on the water/cement ratio. Most field mixers determine the ratio by measuring the density of the slurry, so entrained air causes the slurry to be mixed at improper ratios. Some materials can be used as antifoam agents, but not as defoamers. Other materials act as either defoamers or foam preventers.

Antigelation agents In some cases gelation is caused by the chemical makeup of the cement. Many times this gelation can be controlled by dispersants, but special materials may be required.

Materials

63

DeepCEM additives DeepCEM liquid cementing additives were created for short transition time and early compressive-strength development. Such properties are necessary for isolation and early casing release to ensure successful cementation in the unconsolidated, low-temperature environment of the surface and conductor casings in deepwater wells. They are also useful in other low-temperature situations. DeepCEM additives are discussed in detail on page 56.

Dispersants Dispersants act to reduce the viscosity of cement by breaking up aggregates of the fine cement particles. This reduction in viscosity allows mixing at lower water/cement ratios for higher density, improved fluid-loss control and pumping at reduced pressures.

Expanding additives Expanding additives react chemically after hydration (setting) to produce an increase in the bulk volume of the cement. This reaction provides benefits in zonal isolation and protection of the casing. When used across soft formations, flexible systems may be required to prevent microannulus formation.

Extenders Extenders allow the production of a greater volume of slurry from the powdered cement. This feature can result in reduced cost and, where the extenders are lightweight (or they allow additional water to be used), lower density. The advantage of reduced cost is obvious. Reduced density is important where weak formations are to be cemented. Such weak formations could part and allow loss of the slurry during the cementing operation. A variety of extenders are available to provide for different requirements of lower density, lower cost and other performance parameters.

Fluid-loss control additives Fluid-loss control additives minimize the loss of water from the slurry into permeable formations. This helps to maintain the properties of the cement slurry during placement and until the cement sets.

Gas migration control additives Gas migration control additives are used to reduce the risk of gas invading the cement and migrating into the wellbore. Gas migration in discussed in detail in the section on gas migration control on page 8.

Lost circulation control materials Materials used to prevent or halt losses of slurry from the wellbore are called LCM. In addition to LCM added to the cement, special lost circulation control products are available for combating lost circulation during operations other than cementing. They are discussed in the section on lost circulation systems on page 14.

Retarders Retarders are used to lengthen the time that a cement slurry can be pumped or remains fluid so that other operations (such as pulling pipe after spotting a cement plug) can be performed. They are required at elevated temperatures or when large volumes of slurry require a long time to pump at lower temperatures.

64


Surfactants Surfactants are used in chemical washes and spacers with OBM and to create stable foam when adding a gas to make foamed cement.

Special additives There are a number of additives that do not fit neatly into functional groupings. Fibers are used for controlling lost circulation (see section on CemNET advanced fiber cement). Special types of fibers also improve the impact resistance and tensile strength of cement (see section on DuraSTONE cement). The flexibility of cement can be improved by the use of special additives. This increase in flexibility provides increased resistance to failure by mechanical stresses imposed on the cement during well operation. (See section on FlexSTONE cement.) Granular salt (sodium chloride) and potassium chloride are used primarily to change the ionic nature of the water in the slurry, which helps to minimize adverse formation interactions. In cases where the formation is salt, high concentrations of salt, up to saturation, are commonly used to prevent leaching salt from the borehole wall. Silica is used to combat strength retrogression. Strength retrogression is a change in the hydration products that are formed when cement is exposed to high temperatures (>110°C [230°F]). Silica is available in coarse or fine grades for cementing.

Suspending and antisettling agents Occasionally, segregation can occur in a cement slurry. This segregation may be in the form of water separation (known as free fluid) or in solid particle sedimentation. In either case, a material to suspend the solids is used to maintain slurry integrity.

Thixotropic additives Thixotropic additives produce an intentional gelation of the cement to aid in placement of the cement. Thixotropic cement is discussed as RFC cement on page 56.

UniSLURRY additives UniSLURRY additives have unique and synergistic properties. These additives have been purpose built to perform their function and have properties that distinguish them from other fluidloss or set-control (retarder) additives. UniSLURRY additives, UNIFLAC fluid-loss additive, UNISET LT retarder and UNISET HT retarder are discussed on pages 59–63.

Weighting agents Weighting agents are used to increase the density of the cement when needed for well control.

Spacers Spacers are generally thickened, weighted fluids used to aid in mud removal and to separate the mud from the cement to prevent any compatibility problems.

Chemical washes Chemical washes are generally thin fluids with surfactants to aid in mud removal and to separate the mud from the cement to prevent any compatibility problems. The following tables list additives by functional category (Cementing Additive Quick Guide) and by additive code (Cementing Additive List).

Materials

65

Cementing Additive Quick-Guide Code

Form, Liquid (L) or Solid (S)

Material and/or Application

Application Temperature Range (BHCT except where noted)

S L L S S

Sodium chloride Calcium chloride Set enhancer Calcium chloride Calcium chloride

No limit Below 55°C [130°F] 7–55°C [45–130°F] Below 55°C [130°F] Below 55°C [130°F]

S L L L L

Foam preventer Foam preventer Defoamer Defoamer Defoamer

No limit No limit No limit No limit No limit

L L L

Chemical wash concentrate Surfactant for washes and spacers Chemical wash concentrate

No Limit Maximum 250°C [482°F] No Limit

L L

Low temperatures; nonretarding Set enhancer

Maximum 57°C [135°F] 7–55°C [45–130°F]

S S L L S L L L L

Freshwater systems SALTBOND additive for high-salinity systems Liquid equivalent to D065 SALTBOND additive for high-salinity systems Dispersant, retarder, fluid-loss additive Low temperature Low temperature; nonretarding SALTBOND additive for high-salinity systems Easy-to-disperse cement

Maximum 121°C [250°F] Maximum 121°C [250°F] Maximum 121°C [250°F] Maximum 121°C [250°F] 121–274°C [250–525°F] Maximum 85°C [185°F] Maximum 57°C [135°F] Maximum 121°C [250°F] Maximum 121°C [250°F]

S S S

Additive for RFC and SELFSTRESS systems Low to moderate temperatures High temperatures

Maximum 85°C [185°F] Maximum 110°C [230°F] BHST 80–204°C [176–400°F] BHST

S S S S S L S S S S S

Bentonite Class F fly ash Class F fly ash Diatomaceous earth Expanded perlite Sodium silicate Sodium metasilicate LITEFIL* ceramic microspheres Expanded perlite Attapulgite Class C fly ash

Maximum 232°C [450°F] BHST Maximum 232°C [450°F] BHST Maximum 232°C [450°F] BHST No limit Maximum 232°C [450°F] BHST Limited by ability to retard Limited by ability to retard Maximum 232°C [450°F] BHST Maximum 232°C [450°F] BHST Maximum 232°C [450°F] BHST Maximum 232°C [450°F] BHST

Accelerators D044 D077 D186 S001 S002

Antifoam Agents D046 D047 D144 D175 M045

Chemical Washes D122A D191 D192

DeepCEM Additives D185 D186

Dispersants D065 D065A D080 D080A D121 D145A D185 D604AM D604M

Expanding Additives D053 D174 D176

Extenders D020 D035 D048 D056 D072 D075 D079 D124 D125 D128 D132

66


Cementing Additive Quick-Guide (continued) Code




S S L S

Premium bentonite Microsilica Microsilica Diatomaceous earth

Maximum 232°C [450°F] BHST Limited by ability to retard Limited by ability to retard No limit

S S S L S S L L L

Fluid loss control High-salinity systems SALTBOND additive for high-salinity systems SALTBOND additive for high-salinity systems Low-density systems UNIFLAC additive UNIFLAC additive Low to moderate temperatures, nonretarding SALTBOND additive for high-salinity systems

85–232°C [185–450°F] 38–93°C [100–200°F] About 121°C [250°F] About 121°C [250°F] 4–93°C [ 40–200°F] 0–204°C [32–400°F] 0–204°C [32–400°F] Maximum 121°C [250°F] About 121°C [250°F]

D500 D600G

L L

Maximum 71°C [160°F] 66–121°C [150–250°F]

D700 D701

L L

GASBLOK LT additive for low temperatures Latex GASBLOK MT additive for moderate temperatures Latex GASBLOK HT additive for high temperatures GASBLOK stabilizer for high temperatures

121–191°C [250–375°F] Maximum 191°C [375°F]

S S S S S S

Gilsonite granules Cellophane flakes KOLITE* LCM CemNET fiber CemNET fiber Polyester flakes

Maximum 149°C [300°F] BHST Maximum 132°C [270°F] 538°C [1000°F] BHST Maximum 150°C [302°F] Maximum 232°C [450°F] Maximum 70°C [158°F]

D008

S

54–104°C [130–220°F]

D013 D028

S S

Moderate temperature; also controls fluid loss; used mostly with high-salinity systems Low temperatures High temperatures

D081 D093 D110

L S L

Low temperatures Retarder aid; high temperatures High temperatures

D121 D150

S L

Retarder aid; high temperatures High temperatures

D161 D177 D800

L L S

UNISET additive for high temperatures UNISET additive for moderate temperatures Moderate temperatures

D801

L

Moderate temperatures

Extenders D152 D154 D155 D602

Fluid-Loss Additives D008 D059 D065A D080A D112 D167 D168 D300 D604AM

Gas-Control Agents

Lost Circulation Materials D024 D029 D042 D095 D096 D130

Retarders

Materials

Maximum 85°C [185°F] 104–149°C [220–300°F] 204°C [400°F] (with aid D121) Maximum 85°C [185°F] 149–204°C [300–400°F] 79–149°C [175–300°F] 191°C [375°F] (with aid D121) 110–177°C [230–350°F] 104–149°C [220–300°F] 204°C [400°F] (with aid D121) 85–232°C [185–450°F] 60–121°C [140–250°F] 52–121°C [125–250°F] 154°C [310°F] (with aid D121) 52–121°C [125–250°F] 154°C [310°F] (with aid D121)

67

Cementing Additive Quick-Guide (continued) Code




S S

Additive for MUDPUSH II spacer MUDPUSH WHT additive

Maximum 149°C [300°F] Maximum 232°C (450°F)

D030 D044 D053 D066 D111 D140

S S S S L S

Coarse silica; strength retrogression control Salt Additive for RFC and SELFSTRESS cements Silica flour; strength retrogression control Additive for RFC cement Activator for PERMABLOK plug

D606 J120 M117

S S S

Gelation suppressant Polymer for polymer plug Potassium chloride

No limit No limit Maximum 85°C [185°F] No limit Maximum 85°C [185°F] Maximum 80°C [176°F] 107°C [225°F] No limit 200°F No limit

L L L L L L L L L

Stabilizer for foamed cement Wash or spacer for OBM removal Aid in OBM removal Aid in OBM removal Foaming agent for foamed cement Aid in OBM removal Foaming agent for foamed cement Solvent for OBM removal Solvent for OBM removal

Maximum 232°C [450°F] Maximum 232°C [450°F] Maximum 232°C [450°F] Maximum 232°C [450°F] Maximum 232°C [450°F] Maximum 232°C [450°F] Maximum 232°C [450°F] Maximum 232°C [450°F] Maximum 232°C [450°F]

S L

Antisettling agent Antisettling agent

Maximum 149°C [300°F] Maximum 149°C [300°F]

S L

Additive for RFC and SELFSTRESS cements Additive for RFC cement

Maximum 85°C [185°F] Maximum 85°C [185°F]

S S S S S S S

Ilmenite Barite Hematite Calcium carbonate Micromax Additive for DensCRETE slurries Additive for DensCRETE slurries

No limit No limit No limit No limit Maximum 232°C [450°F] No limit No limit

Spacers D182 D190

Special Additives

Surfactants D139 D607 F040 F057 F078 F103 F104 U066 U100

Suspending Agents D153 D162

Thixotropic Agents D053 D111

Weighting Agents D018 D031 D076 D151 D157 D165 D166

68


Cementing Additive List Code

Name

Application

Description

D008

Retarder/ fluid-loss additive

Moderate temperatures

White powder

D013

Retarder

Low to moderate temperatures

Brown powder

1.23

D018

Ilmenite

High-density slurries

Black granules

3.50–4.50 High-density slurries and spacers to 2300 kg/m3 [19 Ibm/gal].

D020

Bentonite

Cement extender

Light tan to gray powder

2.65

API untreated bentonite. To 25% BWOC when dry blended. About one-fourth as much is required when prehydrated. Minimum density: 1380 kg/m3 [11.5 Ibm/gal]. Attapulgite (D128) is used in salt water.

D024

Gilsonite

Lost circulation control

Black granules

1.07

LCM. Concentration: 10.6–106 kg/t [1–10 lbm/sk]. Temperature to 149°C [300°F].

D028

Retarder

High temperatures

Dark brownish Can be used

1.25

Temperature: 104–149°C [220-300°F]; to 204°C [400°F] with a retarder aid. Concentration: 0.05–1.0% BWOC. Can be used in fresh water and in high-salinity systems.

D029

Cellophane flake


Clear thin flakes

1.45

LCM. Concentration: 1.3–5.3 kg/t [0.125–0.5 Ibm/sk].

D030

Silica

Strength retrogression control

White to tan granules

2.65

100-mesh silica sand. Prevents strength retrogression at temperatures above 110°C [230°F]. Concentration: 35-50% BWOC. D030 is preferred to D066 (silica flour) in dense, low-water-ratio slurries.

D031

Barite

Weighting agent

Grey or tan powder

4.33

High-density slurries and spacers (to 2300 kg/m3 [19 Ibm/gal]).

D035

LITEPOZ 3 extender

Cement extender

Tan to gray powder

2.48

Class F fly ash. Normally substituted for a portion of the cement on an absolute volume basis (e.g., in USA, 35:65) or blended on a bulk volume basis (e.g., in Canada, 1:1).

D042

KOLITE lost circulation additive


Black angular granules

1.30

LCM. Granular material of controlled particle size distribution. Concentration: 10.6–106 kg/t [1–10 lbm/sk].

D044

Granulated salt

Accelerator; inhibit clay swelling; facilitate bonding in salt formations

White granules

2.16

Sodium chloride. Used where formations are sensitive to fresh water. Accelerates cement set when used at concentrations to 15% BWOW (by weight of water). At 18% BWOW, its effect is essentially neutral and thickening times are similar to those obtained with fresh water. Above 18% BWOW, D044 retards setting of cement. Used above 18% to minimize leaching of salt formations.

D046

Antifoam

Control foaming of cement slurries

Tan solid

1.50

General purpose solid foam preventer. Typical concentration: 2 kg/t [0.2 Ibm/sk].

Materials

SG

Primary Purpose Used primarily with high-salinity slurries. Strong viscosifier; provides some fluid-loss control. Concentration: 0.05–1.0% BWOC. Temperature: 54–104°C [130–220°F] as retarder; to 232°C [450°F] as fluid-loss additive. Temperature: to 60°C [140°F] when used alone and 85°C [185°F] with a dispersant. Concentration: 0.1–0.5% BWOC. Can be used in fresh water and seawater.

69

Cementing Additive List (continued) Code

Name

Application

Description

SG

Primary Purpose

D047

Antifoam

Control foaming of cement slurries

Colorless liquid

1.00

General purpose liquid foam preventer. Typical concentration: 4.5 L/t [0.05 gal/sk] for cement slurries and 6 L/m3 [0.25 gal/bbl] for spacers.

D048

LITEPOZ 6 extender

Cement extender

Gray to tan powder

2.01

Class F fly ash. Normally substituted for a portion of the cement on an absolute volume basis (e.g., in USA; 35:65) or blended on a bulk volume basis (e.g., in Canada, 1:1).

D053

Cement agent Thixotropy and expansion

White powder

2.70

Additive for RFC cement and SELFSTRESS cement. Thixotropic slurries (RFC cement) are used for lost circulation control and their expansive properties. SELFSTRESS cement is used for its expansion. Effective up to 85°C [185°F].

D056

Extender

Cement extender

Light gray granules

2.10

Diatomaceous earth.

D059

FLAC* fluidloss additive

Salt cement slurries

White powder

1.36

Fluid-loss control additive for salt slurries. Can be used in fresh slurries with dispersant. Temperature range: 38–93°C [100–200°F]. Typical concentration: 0.5 to 1% BWOC. Retards at low temperatures.

D065

TIC* dispersant

Freshwater or low salinity slurries

Light brown powder

1.43

Powerful cement dispersant. Concentration: 0.1–1.5% BWOC. Can be used with seawater. Temperature to 121°C [250°F].

D065A

SALTBOND additive

Fluid-loss control for high salinity slurries

Light brown powder

1.43

Dispersant and fluid-loss additive for highsalinity slurries when “difficult-to-disperse in salt” cement is used. Temperature to 121°C [250°F].

D066

Silica flour

Strength retrogression control

White to tan granules

2.65

Fine silica flour (finer than 200 mesh). Prevents strength retrogression at temperatures above 110°C [230°F]. Concentration: 35–50% BWOC. Preferred over D030 in lightweight slurries and at very high temperatures.

D072

Perlite

Cement extender

White, fluffy powder

2.40

Expanded volcanic glass. Used in shallow wells; collapses at high pressure (significant at 20.7 MPa [3000 psi]).

D075

Sodium silicate Cement extender

Colorless liquid

1.38

Silicate-based liquid extender. Preferred for seawater applications. When used with fresh water, requires calcium chloride addition to the mix water. Typical concentration: 18–54 L/t [0.2–0.6 gal/sk]. Minimum density: 1380 kg/m3 [11.5 Ibm/gal]. Accelerates set.

D076

Hematite

Reddish brown powder 4.95

High-density slurries and spacers to 2300 kg/m3 [19 Ibm/gal].

D077

Liquid calcium Cement slurry chloride accelerator

Clear to straw colored liquid

1.38

Liquid form of calcium chloride. Used in fresh water or seawater. Maximum concentration of 35.5 L/t (0.4 gal/sk).

D079

Sodium metasilicate

White solid

2.40

Sodium metasilicate extender. Most applicable for low bulk-storage requirements, such as remote locations and offshore. Typical concentration: 0.25–3% BWOC. Minimum density: 1380 kg/m3 [11.5 Ibm/gal]. Accelerates set.

70

Weighting agent

Cement extender



Name

D080

Description

SG

Primary Purpose

TIC dispersant Dispersant

Dark brown liquid

1.24

Liquid equivalent of D065. Concentration: 2–36 L/t [0.02–0.4 gal/sk]. Temperature: to 121°C [250°F].

D080A

SALTBOND additive

Dark brown liquid

1.24

Dispersant and fluid-loss additive for high-salinity slurries when “difficult-to-disperse in salt” cement is used. Temperature: to 121°C [250°F]. Concentration: 27–81 L/t [0.3–0.9 gal/sk].

D081

Liquid retarder Low to moderate temperatures

Brown liquid

1.26

Liquid equivalent to D013. Temperature range: to about 60°C [140°F] when used alone and about 85°C [185°F] with a dispersant. Concentration: 2–9 L/t [0.02–0.1 gal/sk]. Can be used in fresh water and seawater.

D093

Retarder aid

Increase performance range of retarders

White powder

1.73

Synergistic effect with all retarders, increasing their effective range. Most useful above 149°C [300°F]. Detrimental effect on most fluid-loss control additives.

D095

CemNET fiber


Fibers

2.55

Controlling and preventing lost circulation. Maximum temperature: 150°C [302°F]. Concentration: to 7 kg/m3 [2.5 lb/bbl].

D096

CemNET fiber


Fibers

1.27

Controlling and preventing lost circulation. Maximum temperature: 232°C [450°F]. Concentration: to 6 kg/m3 [2.1 lb/bbl].

D110

Retarder

High temperatures

Brown liquid

1.13

Temperature: 79-149°C [175–300°F]; to 190°C [375°F] with D093. Concentration: 2–45 L/t [0.05-0.5 gal/sk].

D111

RFC additive

Liquid additive for thixotropic cement slurries

Light green liquid

1.26

Concentration: to 72 L/t [0.8 gal/sk].

D112

FLAC fluid-loss Low-density slurries additive

Tan powder

1.15

Control fluid loss, primarily in lightweight slurries. Temperature: to 93°C [200°F]. Concentration: 0.5–3.0% BWOC. Can be used in fresh water and seawater. Strong viscosifier.

D121

TIC III tri-functional additive

Dispersant, retarder and aid for fluid-loss control

Dark brown powder

1.38

Temperature: to 177°C [350°F]. Concentration: 0.5–2.0% BWOC. Effective in fresh water and high-salinity systems.

D122A

Chemical wash concentrate

Mud thinning, dispersing and removal

Brown liquid

1.03

Typical concentration: 12 L/m3 [0.5 gal in 41.5 gal] in water.

D124

LITEFIL extender

Ultralightweight cementing additive

Gray powder

0.65- 0.85 Hollow ceramic microspheres allowing slurry density as low as 1080 kg/m3 [9 Ibm/gal]. Temperature: to 232°C [450°F]. Pressure limit owing to crushing of spheres: about 35 MPa [5000 psi].Application ranges may be extended with testing.

D125

Perlite

Extender

Off-white, fluffy powder 2.40

Expanded volcanic glass used in shallow wells; collapses at high pressure (significant at 20.7 MPa [3000 psi]).

D128

Attapulgite

Extender for salt cement slurries


2.65

Clay extender for saline waters (including seawater).

D130

Polyester flake Lost circulation control

Clear thin flakes

1.06

LCM. Concentration: 1.3–5.3 kg/t [0.125–0.5 Ibm/sk].

Materials

Application

Fluid-loss control for salt slurries

71


Name

Application

Description

SG

Primary Purpose

D132

Cement agent

Carbon dioxideresistant cement

Tan to gray powder

2.67

Class C fly ash; component of carbon dioxide-resistant cement.

D139

Foamed cement stabilizer

Foamed cement

Clear to hazy yellow liquid

1.07

Used to maintain downhole stability of foamed cement. Usual concentration: 9 L/t [0.1 gal/sk].

D140

Hardener

Hardener for PERMABLOK lost circulation plug

Yellow liquid

1.24

Hardener for PERMABLOK rigid gel system. Temperature: to 80°C [176°F]. May be extended through laboratory testing to 107°C [225°F]. Concentration: 5–20% by volume of solution, depending on temperature, required gel time and rigidity.

D144

Antifoam additive

High-salinity slurries White liquid and spacers (efficient in any fluid)

1.00

General purpose liquid foam preventer and defoamer. Added to the mix water. Typical concentration: 1–5 L/t [0.01–0.05 gal/sk] for cement slurries and 2.4 L/m3 [0.1 gal/bbl] for spacers.

D145A

Liquid dispersant

Low temperatures

Viscous liquid

1.24

Dispersant, much less retarding than D080. Temperature: to 85°C [185°F] in freshwater systems. Usual concentration: 4 to 27 L/t [0.05 to 0.3 gal/sk].

D150

Retarder

High temperatures

Dark brown liquid

1.11

Liquid equivalent to D028. Temperature: 104–149°C [220–300°F]; to 204°C [400°F] with a retarder aid. Concentration: 2–36 L/t [0.02–0.4 gal/sk].

D151

Calcium carbonate

Weighting agent for spacers

White powder

2.70

Graded calcium carbonate. Weighting material for spacers, especially where acid solubility is required.

D152

Premium bentonite

Extender


2.65

Premium grade of bentonite having better fluid-loss control properties when used at high concentrations (>12%).

D153

Antisettling additive

Suspending additive

White to gray powder

2.53

Maintains slurry stability at downhole temperature conditions. For all densities. Temperature: to 149°C [300°F]. Concentration: 0.1–1.5% BWOC.

D154

Extender

Low temperatures

Gray powder

2.20

Microsilica. Improves performance of most set cement formulations; better strength and lower permeability. Useful for lightweight systems to 1320 kg/m3 [11 Ibm/gal], especially at low temperatures (to 85°C [185°F]). Concentration: 5–20% BWOC.

D155

Extender

Low temperatures

Gray liquid

1.40

Suspension of microsilica in water. Improves performance of set cement; usually gives better strength and lower permeability. Useful for lightweight systems to 1320 kg/m3 [11 Ibm/gal]. Concentration: 90–360 L/t [1–4 gal/sk].

D157

Weighting agent

High-density slurries Red brown powder

4.80

Compatible with freshwater and highsalinity slurries to 232°C [450°F]. Applicable 1920–2640 kg/m3 [16–22 lbm/gal]. Very small particle size (5 micrometers) enables addition directly to mix water, allowing last-minute density increases.

72



Name

Application

Description

SG

Primary Purpose

D161

UNISET HT retarder

High temperatures

Clear liquid

1.08

Compatible with freshwater slurries and salinities to 25% salt BWOW and any density. Works synergistically with UNIFLAC fluid-loss additives. Concentration: 9–225 L/t [0.1–2.5 gal/sk]. Effective temperature: 85–232°C [185–450°F].

D162

Liquid antisettling additive

Sedimentation control Off-white liquid

0.84

Compatible with freshwater and highsalinity slurries. For all densities. Temperature: to 149°C [300°F]. Concentration: 0.45–2.3 L/t [0.005–0.025 gal/sk].

D165

CemHD

DensCRETE slurries

Reddish powder

4.95

Special grade of hematite for DensCRETE slurries.

D166

CemD

DensCRETE slurries

White powder

2.65

Special grade of silica for DensCRETE slurries.

D167

UNIFLAC S additive

Fluid-loss control

White powder

1.32

Compatible with freshwater and high-salinity slurries. Temperature: to 204°C [400°F]. All densities. Typical concentration: 0.1 to 0.8% BWOC.

D168

UNIFLAC L additive

Fluid-loss control

Colorless to yellow liquid

1.08

Liquid version of D167. Compatible with freshwater and high-salinity slurries. Temperature: to 204°C [400°F]. All densities. Typical concentration: 9–81 L/t [0.1–0.9 gal/sk].

D174

Expanding cement additive


Tan powder

3.22

Temperature: 27–110°C [80–230°F]. Typical concentration: 3–5% BWOC.

D175

Antifoam additive

High-salinity slurries White liquid and spacers (efficient in any fluid)

0.99

General purpose liquid foam preventer and defoamer. Added to the mix water. Typical concentration: 1–5 L/t [0.01–0.05 gal/sk] for cement slurries and 2.5 L/ m3 [0.1 gal/bbl] for spacers.

D176

Expanding cement additive

High temperatures

Tan powder

3.54

Temperature: 80–204°C [176–400°F]. Typical concentration: 1–5% BWOC.

D177

UNISET LT additive


Light green liquid

1.10

Can be used with fresh water or seawater. Concentration: to 26 L/t [0.3 gal/sk]. Low sensitivity of thickening time to changes in temperature or concentration. Maximum temperature: 121°C [250°F] if used in combination with UNIFLAC additive (D167 or D168).

D182

MUDPUSH II spacer additive


Red brown powder

1.32

Concentrate for preparing MUDPUSH II spacer; used with freshwater, seawater, or high-salinity spacers. MUDPUSH II spacer density can be designed to 2400 kg/m3 [20 lb/gal]. Temperature: to 149°C [300°F].

D185

Dispersant

Low temperatures

Colorless liquid

1.04

DeepCEM additive for cold environment of deepwater. Nonretarding. Temperature: to 57°C [135°F]. Rheology is not affected by salt (D044) or calcium chloride (S001).

Materials

73


Name

Application

Description

SG

Primary Purpose

D186

Set enhancer

Low temperatures

Green liquid

1.35

DeepCEM additive for cold environment of deepwater. Enhances the set profile of cement; accelerates cement hydration resulting in early compressive strength development. It is especially effective with GASBLOK LT additive (D500) and D185 dispersant. D186 can be used with DeepCRETE systems. Preferred temperature: 7–55°C [45–130°F]. Compatible with fresh water or seawater. Concentration: to17.8 L/t [0.2 gal/sk].

D190

MUDPUSH WHT additive

High temperatures

Colorless powder

1.23

Viscosifies to suspend weighting agents and control fluid loss in MUDPUSH WHT high-temperature spacer, which has a temperature limit of 232°C (450°F). Density: to 2400 kg/m3 [20 lb/gal].

D191

Surfactant

For spacers and washes for removal of OBM

Clear opalescent liquid 0.98

Environmentally friendly surfactant used in washes and MUDPUSH spacers for removal of OBM, low-toxicity OBM or synthetic OBM. Temperature: to 250°C [482°F]. Typical concentration: 48 L/m3 [2 gal/bbl].

D192

Chemical wash concentrate

Mud thinning, dispersing and removal

Dark brown liquid

1.18

Environmentally friendly surfactant used in washes. No limit on temperature.

D300

Fluid-loss additive


Green liquid

1.00

Nonretarding. Compatible with calcium chloride. Compatible with salinity to 10% BWOW. Temperature: 27–120°C [80–250°F]. Concentration: 32–117 L/t [0.35–1.3 gal/sk]. Only dispersants D145A and D185 can be used with D300 fluid-loss additive.

D500

GASBLOK LT additive

Gas migration control at low temperatures

Yellow liquid

1.01

Nonretarding liquid additive. Temperature: to 71°C [160°F]. Density: 1260–1970 kg/m3 [10.5–16.4 lbm/gal]. Compatible with fresh water and seawater. Typical concentration: 45–180 L/t [0.5–2.0 gal/sk].

D600G

GASBLOK MT Gas migration additive control additive

White liquid

1.02

Latex additive. Temperature: 66–121°C [150–250°F]. Concentration: 130–260 L/t [1.5–3.5 gal/sk] in GASBLOK slurries; 90–180 L/t [1–2 gal/sk] as WELBOND cement. Lower concentration is required when used for fluid-loss control only.

D602

Diatomaceous Cement extender earth

White to gray powder

2.10

Naturally occurring material used as extender.

D604AM SALTBOND additive

Fluid-loss control for high salinity slurries

Dark brown liquid

1.21

Salt system dispersant and fluid-loss additive. Temperature: to 121°C [250°F]. Concentration: 27–81 L/t [0.3-0.9 gal/sk].

D604M

Dispersant

“Easy-to-disperse” cements

Dark brown liquid

1.21

Formulated to minimize overdispersion. Temperature: 121°C [250°F]. Concentration: 0.9–9 L/t [0.01–0.1 gal/sk].

D606

Gelsuppressing additive

Antigelling additive

White crystals

2.68

Eliminates primary gelling tendency of cement with improperly balanced sulfate. Typical concentration: 0.5–1.0% BWOC.

74



Name

Application

Description

SG

Primary Purpose

D607

Surfactant


Yellow liquid

0.99

Typical concentration: 2–10% by volume.

D700

GASBLOK HT additive

Gas-migration-control White liquid additive for high temperatures

1.02

Latex additive. Typical temperature: 121–191°C (250–375°F). Concentration: 177–310 L/t [2–3.5 gal/sk]. The addition of D701 (high-temperature latex stabilizer) may be required.

D701

GASBLOK stabilizer

Stabilizer for GASBLOK slurries

Clear yellow viscous liquid

1.05

Used to stabilize D700 GASBLOK slurry; necessary. Typical concentration: 5% by volume of D700.

D800

Retarder


Dark brown powder

1.26

Lignosulfonate retarder with reduced tendency for gelation. Temperature: 52–121°C [125–250°F] BHCT; can be extended to 154°C [310°F] when used with a retarder aid. Compatible with fresh water or salt water (to saturation). Concentration: 0.25–2% BWOC.

D801

Retarder


Dark brown liquid

1.18

Liquid version of D800. Temperature: 52–121°C [125–250°F] BHCT; can be extended to 154°C [310°F] when used with a retarder aid. Compatible with fresh water or salt water (to saturation). Concentration: 4.5-36 L/t [0.05-0.4 gal/sk].

F040

EZEFLO* surfactant


Clear liquid

1.04


F057

Surfactant


Yellow liquid

1.07


F078

EZEFLO surfactant


Clear amber liquid

0.89

Typical concentration: 2–10% by volume. Also used for foaming cement slurries with nitrogen or air. Typical concentration: 19–18 L/t [0.1–0.2 gal/sk].

F103

EZEFLO surfactant


Clear colorless liquid

0.94


F104

Foaming additive

Foamed cement

Clear amber liquid

1.01

For foaming cement slurries with nitrogen or air. Also used in washes and in MUDPUSH spacers for removal of OBM. Typical concentration: 2–10% by volume. Typical concentration: 9–18 L/t [0.1–0.2 gal/sk].

J120

Polymer

Polymer Plug White powder lost circulation system

1.00

Polymer for use in Polymer Plug lost circulation control system.

J237A

Fluid-loss additive

Fluid-loss control in chemical washes

1.06

Typical concentration: 6 L/ m3 [0.25 gal/bbl].

M045

Antifoam additive

Washes and spacers White liquid

1.00

General purpose liquid foam preventer and defoamer. Added to the mix water. Typical concentration: 5 L/t [0.05 gal/sk] for cement slurries and 2.5 L/m3 [0.1 gal/bbl] for spacers.

Materials

Creamy liquid

75


Name

Application

Description

SG

Primary Purpose

M117

Potassium chloride

Clay stabilizer

White to gray crystals

1.98

Used in washes and spacers as a clay stabilizer. Typical concentration: 3% BWOW. Sometimes used in cement slurry to control swelling shales.

S001

Calcium chloride

Accelerator

White solid

1.75

Calcium chloride 77%. Typical concentration: 1 to 2% BWOC. Increases temperature of slurry when dissolved.

S002

Calcium chloride

Accelerator

White solid

1.75

Calcium chloride 95%. Typical concentration: 1 to 2% BWOC. Increases temperature of slurry when dissolved.

U066

Mutual solvent

For spacers and washes for removal of environmentally safe OBM

Colorless to white liquid

0.90

Used in washes and in MUDPUSH spacers for removal of OBM and particularly environmentally safe OBM. Typical concentration: 2–10% by volume.

U100

Mutual solvent

For spacers and washes for removal of environmentally safe OBM

Colorless to white liquid

0.90

Used in washes and in MUDPUSH spacers for removal of OBM and particularly environmentally safe OBM. Typical concentration: 2–10% by volume.

Note: Temperatures, concentrations and other conditions of application are typical. Testing may allow extension of ranges.

76


Equipment Introduction Cementing requires specially designed equipment. Equipment may be high-powered like the CPF-376 double-pump cement trailer or CPT-372 double-pump cement truck or highly versatile to accomplish numerous cementing operations each day, like the CemSTREAK cementing unit. Even more specialized equipment is required for use offshore, with the skids designed to deliver high power with high reliability. In many cases, offshore cementing is done using liquid additives and LAS* liquid additive systems are used for precise delivery of the additives to the mixing system. When subsea heads are used, the DeepSea EXPRESS plug launching system is used for reliable wiper plug launching. Monitoring and recording of the cementing operation is done using the CemCAT computer-aided treatment software and a portable computer. Innovative mixing control is accomplished using the SFM* Solids Fraction Monitor.

CemSTREAK land cementing unit The CemSTREAK land cementing unit is a lightweight, low-maintenance truck with four-wheel drive that can be used for almost any cementing application. Its rugged, compact design enables operation even in hard-to-reach locations. The simplicity of design and extensive test program provide a high level of reliability over rough terrain and in bad weather and allow quick rig-up, rig-down and cleanup. This unit enables as many as six jobs to be performed in one day.

The compact CemSTREAK unit can service wells in difficult-to-reach locations. Designed for fast rig-up and rig-down, the unit can perform multiple jobs in one day.


■

Equipment

77

The CemSTREAK unit is equipped with one triplex pump and two 1.1-m3 [6.9-bbl] displacement tanks, one of which doubles as the mix tank. The hydraulically driven triplex pump allows control of flow rates and pressures and delivers 127 kW [170 hhp] of power. Two centrifugal pumps enable high-energy mixing, pressurizing the triplex pump as well as bringing water onto the unit. The unit carries 38 m [125 ft] of treating hose, rated to 20.7-MPa [3000-psi] working pressure, to serve as the high-pressure conduit to the well. The hose is stored on an automated reel for fast deployment and retrieval. A nonradioactive mass-flow meter provides accurate measurements of slurry density, flow rate and fluid volume even during U-tubing of fluids in the well. Cleaning of the unit starts with the displacement tanks, which minimizes wastewater and hence environmental impact.


Cementing services Low- and intermediate-range pumping services Remedial cementing operations requiring very low pump rates Low-range pressure testing

Benefits ■ ■ ■ ■ ■ ■ ■

Ability to reach difficult locations Savings in rig time through rapid rig-up and rig-down Minimal environmental impact Weight compliant with various road ban rules Crew of only two operators for improved logistics, reduced risks and costs Downtime probability reduced or eliminated by reliability of equipment Ability to mix all slurry types

Features ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■

78

Four-wheel drive 127-kW [170-hhp] triplex pump Rating of 20.7-MPa [3000-psi] working pressure 38 m [125 ft] of 50.8-mm [2-in.] hose rated to 20.7-MPa [3000-psi] working pressure Powered reel for hose storage, deployment and retrieval 1.11-m3/min [7-bbl/min] pump rate Nonradioactive densitometer SLURRY CHIEF Mark III cement mixer Oilfield or metric gauges Integrated data-acquisition system Two 1.1-m3 [6.9-bbl] displacement tanks CemCAT real-time monitoring Four separate systems for pressure relief Self-sufficient unit, including cement head and extra treating iron


CPF-376 double-pump cement trailer This cement trailer is a state-of-the-art mixing and pumping unit for land operations. The highpower unit allows mixing and pumping cement at rates to 2.7 m3 [17 bbl/min] and at pressures to 68.95 MPa [10,000 psi]. Pumps are available with rating to 137.9 MPa [20,000 psi]. The unit is fully redundant, allowing operations to continue in the event of failure of one of its components. A SLURRY CHIEF mixer with automated density control is used in conjunction with a

The CPF-376 double-pump cement truck delivers high reliability in high-pressure pumping operations.

0.95-m3 [6-bbl] mixing tub and a 2.2-m3 [14-bbl] averaging tank. This arrangement produces superior density control and separates the critical mixing stage from downhole pumping. It also provides the ability to mix 3.2 m3 [20 bbl] of cement in batch mode for squeeze and plug operations. The CemCAT system is used to monitor and record treatment parameters and to provide a job report.


Cementing services High-power pumping services Remedial cementing operations


Equipment

Full redundancy ensures ability to complete job Downtime reduced or eliminated by reliability of equipment Ability to mix all slurry types

79

Features ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■

194-kW [260-hhp] power per triplex pump, for a total of 388 kW [520 hhp] 2.7-m3/min [17-bbl/min] pump rate Working pressure rating to 137.9 MPa [20,000 psi] Fully redundant for high reliability SLURRY CHIEF Mark III cement mixer Automatic density control system Two nonradioactive densitometers Oilfield or metric gauges Underdrive for pumping at low rates Direct drive centrifugal pumps for reliability Integrated data-acquisition system CemCAT real-time monitoring Self-sufficient unit, including treating iron

CPT-372 double-pump cement truck The CPT-372 truck is a high-power cement mixing and pumping unit that allows mixing and pumping at rates to 2.7 m3 [17 bbl/min] and at pressures to 68.95 MPa [10,000 psi]. The unit is fully redundant, allowing operations to continue even if one component fails.

The CPT-372 double-pump cement truck delivers high reliability in high-pressure pumping operations.

80


A SLURRY CHIEF mixer is used in conjunction with a 0.95-m3 [6-bbl] mixing tub. This arrangement produces superior density control and separates the critical mixing stage from downhole pumping. It also provides ability to mix a maximum of 3.2 m3 [20 bbl] of cement in batch mode for squeeze and plug operations. The CemCAT system is used to monitor and record treatment parameters and to provide a job report.


Cementing services High-power pumping services Remedial cementing operations


Full redundancy ensures ability to complete job Downtime reduced or eliminated by reliability of equipment Ability to mix all slurry types

Features ■ ■ ■ ■ ■ ■ ■ ■ ■ ■

Power to 388 kW [520 hhp] Pump rate to 2.7 m3/min [14 bbl/min] Working pressure rating of 68.95 MPa [10,000 psi] Fully redundant for high reliability SLURRY CHIEF Mark III cement mixer Nonradioactive densitometer Oilfield or metric gauges Integrated data-acquisition system CemCAT real-time monitoring Self-sufficient unit, including treating iron

Offshore cementing skids Schlumberger provides a versatile line of CPS* cement pumping skids specially designed to meet all offshore cement mixing and pumping requirements. These skids can produce up to 1490 kW [2000 hhp] for high-pressure pumping. Two triplex pumps equip the unit for simultaneous high-energy mixing and downhole pumping or for parallel downhole pumping. Two engines (diesel or electric) power the unit. The design focuses on reliability, redundancy and noise reduction. The units are typically controlled from a local console but optional remote control packages are available. Optional marine cooling kits and a helicopter lift unit are available. Cement slurries are mixed using the SLURRY CHIEF recirculating mixer fitted with an SFM quality control monitor or an SFM-C* process control unit for automatic density control. The SLURRY CHIEF unit mixes consistent slurries at rates to 1.75 m3/min [11 bbl/min]. Equalizing tubs provide excellent slurry uniformity (3 m3 [19 bbl]).

Equipment

81

CPS cement pumping skids are available in a number of configurations to fit any requirement.

Offshore cementing skids are fitted with all sensors necessary for direct connection to the CemCAT data-acquisition and monitoring system. The CemCAT system monitors and records the critical job parameters including rate, pressure and slurry density. Batch mixers, such as the CBS-961 twin 50-bbl mixer, are available for mixing of cement slurries or other fluids. The CBS-961 unit features two centrifugal pumps for picking up fluids from remote tanks, recirculating for mixing and for delivering fluid to high-pressure pumps.

Standard equipment ■ ■ ■ ■ ■ ■ ■ ■

SLURRY CHIEF cement mixer Nonradioactive densitometer Two triplex pumps Stainless-steel displacement tanks Slurry pump Recirculation pump Two mixing water pumps Full selection of fluid ends

Optional equipment ■ ■ ■ ■ ■ ■ ■ ■ ■

82

SFM package Automatic density control Zone II-certified engine package Remote control package Split skid with bulkhead Optional loose equipment skid Marine cool kit Liquid additive metering system Soundproof enclosure (for CPS-601 and CPS-665 units)


Applications ■ ■ ■ ■ ■ ■

All cementing jobs High-pressure pumping services Fluid pickup from remote sources Metering of mixing fluids Metering and pumping of displacement fluids Downhole pumping using one or both triplex pumps

Table 6-1. Dimensions of Offshore Cementing Units CPS 361

CPS 601

CPS 665

CPS 763AC

CPS 763DC

CPS 2000

Length (mm [in.])

6,511 [256]

7,710 [304]

7,863 [310]

8,180 [322]

7,823 [308]

7,164 [282]

Width (mm [in.])

2,578 [102]

3,011 [119]

2,898 [114]

3,007 [118]

3,150 [124]

3,841 [151]

Height (mm [in.])

3,043 [120]

3,467 [136]

3,333 [131]

3,339 [132]

3,323 [131]

3,267 [129]

32,180 [70,960]

33,840 [74,600]

37,360 [82,380]

38,010 [83,810]

46,795 [103,180]

Operating weight (kg [lbm]) 20,658 [45,550]

Table 6-2. Performance of Offshore Cementing Units CPS 361

CPS 601

CPS 665

CPS 763AC

CPS 763DC

CPS 2000

Power (kW [hhp])

410 [550]

626 [840]

1044 [1400]

1194 [1600]

1194 [1600]

1490 [2000]

Max. rate at 41.4 MPa [6000 psi] (m3/min [bbl/min])

1.6 [10]

3.1 [19.7] at 46.9 MPa [6800 psi]

2.9 [18.3]

2.9 [18.3]

2.9 [18.3]

3.8 [24.0]

LAS liquid additive system Modular systems, such as the CMP-351 unit, deliver metered amounts of liquid additives to the cement slurry as it is mixed. Metering of liquid additives adds versatility to the mixing process, enabling the mixing of various slurry systems from bulk storage of neat cement. Metering can be manual, or automatic when the CMP-751 LAS metering unit is used. With the CMP-751 unit, electromagnetic flow meters control the additive metered into the displacement tanks.


Offshore cementing operations Operations in remote areas

Benefits ■ ■ ■ ■ ■ ■

Equipment

Allows use of neat (unblended) cement for all operations Provides high versatility in slurry designs Simplifies logistics Enables last-minute design without regard to time of transport from base Eliminates waste of unused blended cement Enables decisions on treatment volumes at time of job

83


Meters up to four different additives into mixer Stainless-steel construction for durability Remote control of additive addition Certified for Zone II operations Electromagnetic flow meters

CemCAT cementing computer-aided treatment software The CemCAT system is a quality control (QC) and data-acquisition software for acquiring, recording, displaying, and reporting cementing and related pumping treatment data in real time. CemCAT system real-time displays and plots present detailed job information to decision-makers. User friendly and quickly accessible, the CemCAT system provides enough defaults for the system to be used quickly with a minimum of user input, or it can be completely customized. By acquiring data from existing hardware on cementing units, the CemCAT system provides efficient data transfer between the Wellsite Reporting System and Schlumberger CemCADE cementing design software. Integration of up-to-the-minute data with design and evaluation software results in precise treatment design and execution. During the job, the CemCAT system tracks the design and displays actual job parameters compared with planned values. With the CemCAT system, quality assurance (QA)/QC plots can be generated at the end of each treatment to determine if a job was pumped within the designed density range. Internet connectivity allows the transmission of data from a remote wellsite to anywhere in the world for real-time analysis. The CemCAT system also provides the means to easily archive job data for future use.


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Primary and remedial cementing operations Miscellaneous high-pressure pumping services for testing blowout preventers or for leakoff or formation integrity tests Matrix acidizing and coiled tubing services


Superior QC during all treatment phases Precise treatments that follow job design Immediate data for job-critical decisions, thus reducing risk Exceptional flexibility, performance and reliability


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Complete integration with CemCADE design and evaluation software Clear, customizable digital displays and plots of job data Real-time data transmission from wellsite to any location worldwide Detailed postjob plots including QA and QC plots and reports Archive of job data for future use


SFM-C process control An important element of successful low-density slurry placement and ideal set-cement properties is QC. A key measure of quality in cement slurries is the solids fraction, which is the percent of dry components in the slurry. In a conventional cementing operation, densitometers measure slurry density, and the solids fraction can be calculated from the density measurements. Variation in the solids fraction of the slurry affects all the cement properties. Too many solids and the slurry will be too viscous and set early. Too few solids and free fluid will be high and the compressive strength will be low and develop late. For certain slurries, such as very low density slurries, slurry quality cannot be determined using density measurements. In ultralightweight slurries, the densities of the dry blend and the mix water can be nearly the same, so density measurements cannot discriminate between water and solids. The density would be the same, even if the slurry consisted entirely of water. For example, a slurry designed at 1020 kg/m3 [8.5 lbm/gal] with 57% solids content and monitored using only a densitometer with a variation of ± 12 kg/m3 [0.1 lbm/gal] in density will have a solids content ranging from 24% to 84%. The SFM-C process control system provides a new method for real-time slurry QC that accurately determines and controls solid/liquid ratios without making density measurements. The system measures the rate of mix water and slurry flows and calculates the solids fraction from those measurements. From this determination, the fluid density is easily computed. The solids fraction is automatically maintained by process control of the water and cement flow into the mixer.

SFM-C system instantly displays critical data in convenient, readable formats. Equipment

85

Slurry density Slurry rate Solid fraction

Solid fraction (%)

10 9 8 7 6 5 4 3 2 1 0

100 90 80 70 60 50 40 30 20 10 0 0

5

10

15

20

25

30

35

40

Slurry density (lbm/gal) Slurry rate (bbl/min)

45

Time (min)

Volume (%)

100 90 80 70 60 50 40 30 20 10 0

88% of volume ± 2% of the solid-fraction target 99% of volume ± 0.2 lbm/gal

0

10

20

30

40

50

60

70

80

90

100

Solid fraction (%) The SFM-C system controls the solids fraction, which in turn controls the density.

The SFM-C system is a complementary technology, designed to provide QC for very low density LiteCRETE slurry systems. Although SFM-C technology was developed specifically for lightweight-cement operations, it is effective for slurries of any density. This new SFM-C technology allows cementing crews to maintain slurry properties while continuously mixing and pumping large slurry volumes. The system requires a slurry flow meter, such as the nonradioactive densitometer already available on cementing units, a residence tank sensor, a water flow meter and process-controlled valves. These retrofits can be added easily to land or offshore mixing equipment. User-friendly software helps cementing crews monitor and easily switch between automatic and manual control.


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All cementing operations Slurries with very low densities (less than 1320 kg/m3 [11 lbm/gal])


Benefits ■

Excellent QC

Features ■ ■ ■ ■ ■ ■ ■

Continuous-mixing control of all slurries, even at densities equal to or lower than that of water More sensitive method for controlling cement mixing than by density measurement Independent of specific gravity of components Automatic control of slurry quality Real-time monitoring Complete compatibility with all data-acquisition systems Easy installation on conventional mixing equipment

Nonradioactive densitometer Density measurement and control in the oil industry have traditionally been accomplished by using radioactive densitometers, mainly because they are nonintrusive, durable and easy to use. Unfortunately, the radioactive technique has several major drawbacks; the radioactive source presents safety and environmental concerns, and the required accuracy (12 kg/m3 [0.1 lbm/gal]) is difficult to attain. Because of the deficiencies of radioactive densitometers, Schlumberger uses a nonradioactive densitometer that employs a proven method; poses no health, safety, or environmental hazard; and provides direct density measurements with an accuracy of better than 12 kg/m3 [0.1 lbm/gal]. The nonradioactive densitometer is extremely reliable, easy to use and requires no on-site calibration. Additionally, it measures flow rate with an accuracy of ±0.5% of reading and can be used as a flow-measurement instrument for acidizing service. The vibrating tube principle governs the density measurement in the nonradioactive densitometer.

The nonradioactive densitometer is a rugged, field-proven instrument with excellent reliability.

Equipment

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Cementing operations with slurry density over 1200 kg/m3 [10 lbm/gal] Land and offshore (including Zone II) Process controlled operations Can be used for acidizing service


Accurate density measurement Reliability, requires no on-site calibration Minimal environmental and safety concerns


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No radioactive source Superior accuracy and field-proven reliability for measuring density and flow rate Accuracy greater than 12.0 kg/m3 [0.1 lbm/gal] Virtually maintenance-free Easy configuration; easily drained and cleaned in place Output (density, rate) independent of changes in temperature, pressure, flow profile or viscosity Fast response time


Evaluation Introduction Cement evaluation plays an important role in the cementing process. By cement evaluation, the quality of zonal isolation is confirmed. In cases where zonal isolation is not achieved, the evaluation helps diagnose the problems that led to the poor zonal isolation. Consequently, methods and slurry design used for the primary cementing are reviewed and improved for the next well. Results also help in deciding whether remedial work is required. Cement evaluation and QC are processes completed during and after every step of primary cementing. During the design, using Schlumberger CemCADE design software, the design engineer uses well data and cementing parameters to predict the results with selected cement systems, selecting the one providing the desired zonal isolation. During execution, the operation is monitored and analyzed. Finally, in the evaluation, cement evaluation logs are acquired for final confirmation of hydraulic zonal isolation. Thus, cement evaluation is a continuous process beginning with the design and continuing with execution analysis, post-treatment analysis and analysis of cement evaluation logs to determine zonal isolation.

Design In the design the well data are entered into CemCADE software to ensure optimum WELLCLEAN mud removal, pipe centralization, cement slurry for downhole conditions, flow rate, etc. The execution, as designed, is simulated and theoretical mud removal and zonal isolation are assessed. If results are not satisfactory, the design is revised and the simulation is rerun. See page 29 for more information on CemCADE software and WELLCLEAN mud removal.

Execution analysis The purpose of primary cementing is to achieve zonal isolation. The slurry composition and the execution procedure are designed to provide complete zonal isolation. The properties of the cement sheath are optimized to isolate all productive zones, as well as those containing water and nuisance gas. The first QC step and evaluation during the execution determines if the materials were mixed according to the design and if the displacement process followed the prescribed procedure. This evaluation is made using plots of the slurry density, solids fraction, flow rate and pumping pressure during the execution. See page 84 for more information on CemCAT monitoring software.

Postcementing analysis If the execution analysis indicated abnormal values of any monitored parameters, a thorough analysis is performed after the operation. The data acquired during the cementing operation are loaded into CemCADE cementing design and evaluation software and the execution data can be overlaid and compared with the simulation run during the design. The simulation can also be rerun using density and volumes of fluid mixed and pumped to determine if mud removal parameters were met.


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Evaluation

89

Cement evaluation logs are acquired for final confirmation of hydraulic zonal isolation and tops of cement. Using the analysis from both steps, any problem areas can be highlighted with special attention to the depths on the evaluation logs where isolation is a concern.

Cement evaluation services Cement evaluation services are used in the final evaluation of cement integrity and zonal isolation. Used in conjunction with the execution and the postcementing analyses, evaluation logs can help identify poor isolation and the reasons for that poor isolation. If remedial work is necessary, evaluation logs assist in its design to achieve the required isolation for well completion and production of desired fluids. Any problem identified in these analyses is targeted for improvement in the design or execution phases for future wells. Cement evaluation services also play an important role in confirming the pipe’s integrity, support and isolation from formation fluids, because exposing pipe to formation fluid can eventually lead to corrosion if the lack of isolation is not corrected. Cement evaluation services are divided into two major groups: ■ Acoustic logging can be either sonic services, with tools that provide a log of amplitude measurements and Variable Density* sonic waveforms, or ultrasonic services, with tools that provide a map of the cement distribution around the pipe. ■ Other logging tools provide indirect evaluation through measurements of pressure, temperature, nuclear activity and noise. SoniCalc software is a tool that allows the logging engineer to import well and cementing data for use in tool setup and interpretation of cement bond logs (CBLs) and USI UltraSonic Imager cement evaluation logs. Tool setup parameters are provided so that tool setup and computed output are correct for the well being logged, improving logging service quality. These data also assist in interpreting evaluation logs and in determining if remedial treatments may be required. Only acoustic tools are discussed in this catalog.

Sonic services CBLs, with amplitude and/or attenuation and Variable Density waveform data, have been the primary method for cement quality evaluation for many years. The principle of the cement bond measurement is to record the transit time and amplitude (or attenuation) of a 20-kHz acoustic wave after propagation through the well fluid and the pipe wall. The measurement is the amplitude in millivolts of the tubular first arrival (E1) at a receiver with 0.91-m [3-ft] or shorter spacing. The amplitude of the signal is a function of the attenuation by the shear coupling of the cement sheath to the pipe. The attenuation rate depends on the cement acoustic impedance, cement thickness, pipe diameter, pipe thickness and percentage of bonded circumference. A receiver with 1.52-m [5-ft] spacing is used to record the Variable Density waveform for better discrimination between sonic waves traveling through pipe and those through formation. This measurement is generally used to qualitatively assess the cement-to-formation bond. SlimAccess tool

The SlimAccess* wireline logging tool is designed for slim, complex-geometry boreholes. It generates, records and digitizes acoustic waves and provides CBL amplitude, Variable Density measurement and attenuation measurement for cement bond evaluation. It is also used for openhole applications such as seismic correlation, porosity measurement and evaluation of lithology. It has a short-spacing 0.30-m [1-ft] transmitter-receiver for cement evaluation in fast formations. Besides the primary transmitter-receivers used for CBL and Variable Density measurement, the SlimAccess tool also uses a second set of transmitter-receivers for backup. It is a monopole sonic tool with a diameter of 6.35 cm [21⁄2 in.], which enables it to be run in 14-cm [51⁄2-in.] casing.

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The SlimXtreme* tool is the version of the SlimAccess tool for use in slim, complex-geometry boreholes under HPHT conditions. Applications ■ ■ ■ ■

Determine quality of pipe to cement bond Determine quality of formation-to-cement bond Identify cement top HPHT wells (SlimXtreme tool)

Benefits ■ ■

Logging in pipe as small as 14 cm [51⁄2 in.] Log quality minimally affected by environmental conditions

Features ■ ■ ■ ■

0.30-m [1-ft] receiver for cement evaluation in fast formation 6.35-cm [21⁄2-in.] diameter Low sensitivity to environmental conditions Combinable with ultrasonic imaging tool for enhanced interpretation

SCMT Slim Cement Mapping Tool

The SCMT* Slim Cement Mapping Tool is a sonic tool that provides a radial cement attenuation variation map from a 0.61-m [2-ft] eight-segment receiver, as well as conventional 0.91-m [3-ft] amplitude (attenuation) and 1.52-m [5-ft] Variable Density data. In addition, the 0.61-m [2-ft] mapping receivers are effective for cement evaluation in fast formations where the 0.91-m receiver might give ambiguous results. Because of its slim size (4.29-cm [111⁄16-in.] diameter), the tool can be run through tubing. The SCMT tool can be run in combination with the PS Platform* new-generation production services platform or the RST* Reservoir Saturation Tool for complete well and reservoir evaluation in one trip. The principal application of the SCMT log is cement quality and integrity evaluation around the entire circumference of the pipe. Applications ■ ■ ■

Determination of quality of pipe-to-cement bond Qualitative evaluation of cement-to-formation bond Identification of cement top


Tubing does not have to be removed from well (no rig required). Interpretation is valid, even in fast formations. Time is saved when the tool is run in combination with other tools.

Features ■

■

■ ■ ■

Evaluation

Combinable with PS Platform suite or RST tool for well, reservoir and cement integrity evaluation in the same run Combinable with PipeView* multifinger caliper tool for PS Platform tool string, for cement and pipe integrity evaluation in the same run giving complete well integrity diagnosis 4.29-cm [111⁄16-in.] diameter 8-segment receiver for bond variation mapping 0.61-m [2-ft] receiver 91

A SCMT log showing possible channel and its position aids in decision to squeeze and in design of the squeeze cementing treatment.

Ultrasonic services USI UltraSonic Imager

The USI UltraSonic Imager provides an accurate and reliable high-resolution, comprehensive, real-time answer product revealing pipe-to-cement bond quality and downhole pipe condition. Using ultrasonic technology, the USI tool sends ultrasonic pulses between 200 kHz and 700 kHz that travel through the well fluid and strike the casing, providing 360º azimuthal coverage using a single rotating transducer. The transducer receives reflected signals that have undergone multiple reflections between the casing internal and external interfaces. The signal decays at a rate dependent on the acoustic impedance of the material in the annulus. USI log maps of the acoustic impedance of the material in the annulus are generated using very advanced processing techniques. From the acoustic impedance values, the material in the annulus is identified and maps are prepared showing the nature (gas, liquid, solid) of the material in the annulus. High-resolution maps of pipe wall thickness, internal radius and inner wall rugosity are provided for accurate evaluation of the pipe condition. The results are displayed in real time as quantitative, self-explanatory interpreted cement and pipe integrity maps. The combination of the USI tool with CBL and Variable Density tools provides enhanced assessment of cement-to-pipe and cement-to-formation bond quality. Applications Cement integrity ■ ■ ■ ■ ■ ■

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Hydraulic zonal isolation evaluation Remedial work decision-making and assessment of effectiveness Primary cementing process improvement Identification of gas invasion Determination of casing support before sidetrack Cement top identification and free pipe identification for pipe retrieval


Pipe integrity ■ ■ ■

Quantification of internal and external corrosion, wear, metal loss and/or scale buildup Identification and quantification of pipe distortion Selection of optimal packer setting depth

Benefits ■ ■ ■ ■ ■ ■

Detailed channel identification and location Remedial cementing optimization Microannulus identification Accurate, effective real-time answers Rig time saving by acquiring cement and pipe integrity data in one run Continuous improvement of cementing process

Features ■ ■ ■ ■ ■ ■ ■

Cement map showing cement quality and presence of channels Pipe integrity data Wellsite product for enhanced three-dimensional (3D) visualization 100% azimuthal coverage by a single, rotating transducer 5º radial and 3.81-cm [11⁄2-in.] vertical resolution in high-resolution mode Combinable with inclinometry tools to aid image orientation in deviated wells Combinable with CBL tools for enhanced evaluation

A USI log with optional Variable Density data provides the best identification of uncemented channels and aids in decisions to squeeze and in design of the squeeze cementing treatment.

Evaluation

93

The USI log provides several presentations reflecting different applications. The easily readable, color-coded images make cement coverage in the annulus easy to interpret. Problems such as channels in cement and tubular damage can be seen directly on the images, thus revealing the status of zonal isolation for decisions about remedial work. Enhanced field products allow visualization of the cement distribution and quality, as well as a 3D view of pipe condition to further facilitate remedial work decisions. QC log presentations are used for data validation. Cement integrity evaluation is essential, not only for zonal isolation confirmation and help in the remedial work decision and design, but also for the determination of the causes of poor cementing procedures. All acoustic logs are sensitive to cement-to-pipe bond. Some measurement methods are affected by downhole conditions more than others and in different ways. For this reason, a USI log and CBL combination is advisable to help diagnose zonal isolation problems at the cement/pipe interface and the cement/formation interface. A full analysis of the cement evaluation logs will assist in diagnosing the problem and provide information to improve the cementing. Thus, USI logs and CBLs with Variable Density data should be acquired together because their responses area complementary, especially in the presence of ■ microannulus (liquid or gas) ■ thin cement sheath ■ fast formation ■ double strings of casing ■ heavily corroded casing ■ inside deposits (cement, rust) ■ high-attenuation mud ■ lightweight cement. The table shows the USI log and the CBL response under the different conditions. Effects on Evaluation Logs USI Log

CBL

Resolution

5° radial and 3.81 cm [11⁄ 2 in.] vertical

360° by 0.91 m [3 ft]

Well-bonded cement

Cement (high acoustic impedance)

Low amplitude or high attenuation; characteristic Variable Density log

Lightweight cement

Acoustic impedance based on properties of the cement; special processing may be required for very low density cement

Complicates interpretation

Dry microannulus and/or debonded cement

Affected: Resolved by special processing


Mud layer

Slightly affected


Wet microannulus

Slightly affected


Contaminated cement

Shown as solid with low acoustic impedance if set


Mud channel

Displayed as channel filled with liquid


Gas channel

Shown as channel filled with gas


Formation bond

Not discriminated

Qualitatively indicated on Variable Density plot

Outer casing/ hard formation

Slightly affected

Strongly affected if cement sheath is thin

Casing condition

Very sensitive: Corrosion, wear and deformed casing can be quantified in alternate acquisition mode

Slightly affected: No indication on log of quality

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The USI log measures the bonding between the pipe and the cement, and the Variable Density display indicates the bonding between the cement and the formation. The advantage of the USI log over the traditional CBL is at the cement-pipe interface. The USI log ■ identifies liquid-filled microannulus ■ identifies microdebonding ■ identifies channels as small as 3.05 cm [1.2 in.] ■ evaluates thin cement sheath. The processed USI log and CBL with Variable Density data can be displayed side by side for complete visual cement evaluation in real time at the wellsite. This feature helps the completion engineer make sound decisions on remedial actions. The combination also helps cementing companies in the continuous improvement and enhancement of their cementing systems and methods for best hydraulic isolation and cement integrity results. Nonstandard environment

The evaluation of ultralightweight cement systems or logging in heavy mud or nonstandard casing sizes may require advanced interpretation. For further information about cement evaluation services, please refer to www.slb.com/oilfield.

Evaluation

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Glossary

Absolute Volume. Volume a solid occupies or displaces when added to water divided by its weight: the volume per unit mass. Units are gallons per pound or cubic meters per kilogram. American Petroleum Institute (API). Organization which standardizes materials and procedures for use in oilfield. API Cement. One of several classes of cement manufactured to the specifications of API Specification 10A. Classes of API cement are A, B, C, D, E, F, G and H. API Recommended Practice 10B. Recommended Practice for Testing Well Cements. The standard which gives guidelines for testing methods for cements and cement formulations for use in well cementing. Procedures are intended to be modified to conditions of the well.

Bond Log. See Cement Bond Log. Bottomhole Circulating Temperature (BHCT). The temperature that occurs at the bottom of a well while fluid is being circulated. The temperature used for most tests of cement slurry in a liquid state (thickening time, fluid loss, etc.). In most cases, is lower than the BHST, but in some cases, such as in deepwater or in the arctic, may be higher than BHST. Bottomhole Static Temperature (BHST). The undisturbed temperature at the bottom of a well. After circulation and the well is shut in, this temperature will be approached after about 24–36 hr, depending on conditions. The temperature used in most tests in which the cement slurry is required to set or is set. Bulk Volume. The volume per unit mass of a dry material plus the volume of the air between its particles.

API Specification 10A. Specification for Cements and Materials for Well Cementing. The standard which specifies requirements for API well cements and specification testing methods.

BWOB. See By Weight of Blend.

API Water. The amount of mixing water specified in API Specification 10A for specification testing of cement to meet API requirements. This amount in not intended to be a guide for mix water requirements in field applications.

By Weight of Blend (BWOB). Used to define the amount (in percent) of a material added to cement when the material is added based on the total amount of a specific blend.

Base Slurry. Conventional cement slurry used as the cementitious component of a foamed cement slurry. Bc. See Bearden Units of Consistency. Bearden Units of Consistency (Bc). The pumpability or consistency of a slurry is measured in Bearden units of consistency (Bc), a dimensionless quantity with no direct conversion factor to more common units of viscosity. BHCT. See Bottomhole Circulating Temperature. BHST. See Bottomhole Static Temperature. Blaine Fineness. The particle size or fineness of a cement in cm2/g or m2/kg as determined from air permeability tests using a Blaine permeameter.


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Glossary

BWOC. See By Weight of Cement. BWOW. See By Weight of Water.

By Weight of Cement (BWOC). Used to define the amount (in percent) of a material added to cement. The method used for most additives in the dry form. By Weight of Water (BWOW). Used to define the amount (in percent) of a material added to a cement slurry based on the weight of water used to mix the slurry. Normally used only for salt. Cement Bond Log (CBL). An acoustic log used to measure the attenuation rate of a sound wave propagating along the casing. Can be used as an indication of the quality of cement in the annulus. Consistometer. Laboratory apparatus used to determine the thickening time of a cement slurry as described in API Specification 10A and API Recommended Practice 10B.

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Consistency. A rheological property of matter which is related to the cohesion of the individual particles of a given material, its ability to deform and its resistance to flow. The consistency of cement slurries is determined by thickening time tests in accordance with API Recommended Practice 10B and is expressed in Bearden units of consistency (Bc). Contact Time. The elapsed time required for a specific fluid to pass a designated depth in the annulus during pumping operations. Critical Rate. The minimum rate required to achieve turbulent flow. Curing. The ageing of cement under specified conditions of temperature and pressure. Dehydration. Loss of water from cement slurries or drilling fluid by the process of filtration. Results in the deposition of a filter cake and loss of the slurry’s internal fluid into a porous matrix. The cement is not completely dehydrated (sufficient water remains to allow setting of the cement). Difficult-to-Disperse (DTD). Cement which is not easily dispersed by a material known as a dispersant. Difficult-to-Disperse in Salt (DTDS). Cement which is not easily dispersed by a material known as a dispersant when the slurry is mixed with water containing a high concentration of salt. DTD. See Difficult-to-Disperse. DTDS. See Difficult-to-Disperse in Salt. Easy-to-Disperse (ETD). Cement which is highly sensitive to the concentration of dispersant, often leading to slurry stability problems. Easy-to-Disperse in Salt (ETDS). Cement which is highly sensitive to the concentration of dispersant when the slurry is mixed with water containing a high concentration of salt. Overdispersion often leads to slurry stability problems. Effective Laminar Flow. A technique for effectively displacing drilling mud from the annulus using a laminar flow regime. Equivalent Sack. The weight of any cementitious material or blend based on the absolute volume of the cement. Normally used to define a “sack” of cement blend in which part of the cement has been replaced, on an absolute volume basis, by a pozzolanic material such as fly ash. ETD. See Easy-to-Disperse.

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ETDS. See Easy-to-Disperse in Salt. Expanding Cement. Cement system exhibiting a bulk volumetric increase after setting. Fill Cement. A cement system used to provide zonal isolation across generally nonproductive zones located above the zones of interest. May also be called lead cement. Fly Ash. The noncombustible residue from the burning of pulverized coal. Fly ash is pozzolanic and is frequently used to replace a portion of the cement and reduce its density. Foamed Cement. A homogeneous, ultralightweight cement system consisting of base cement slurry, gas (usually nitrogen) and surfactants. Free Fluid. The volume of fluid (expressed in percent) separating from a cement slurry when left static. Measured as specified in API Recommended Practice 10B. Once called free water. Gas Migration. A generic term which covers all possible routes for annular gas entry and propagation through and around the cement sheath. Also known as annular gas flow. Gel Strength. The degree to which a fluid behaves as a solid when left static. Gilsonite. An asphaltinic material frequently used as LCM for drilling fluid and cement. Grind. The fineness to which cement is ground. Also may refer to a specific production of cement (e.g., lot number). Hydraulic Cement. A substance which, when mixed with water, becomes hard like stone because of a chemical reaction with the water. Hydraulic cement will set under water. Lead Cement. See Fill Cement. Liquid Additive. A material used in a liquid form to modify the properties of cement for use in oil- or gaswell cementing. LITEPOZ. A term used by Schlumberger for certain materials added to cement that are lightweight and have pozzolanic properties. Microannulus. Small gap between the casing and cement sheath resulting from downhole stresses (pressure or temperature). Neat Cement. Cement containing no additives. POD. See Point of departure.


Point of departure (POD). A term used to describe the beginning of thickening of a cement slurry during the thickening time test. For some slurries, the POD is used as the thickening time. Portland Cement. The product obtained by pulverizing clinker consisting essentially of hydraulic calcium silicates. Portland Cement Clinker. Hard granular nodules composed essentially of hydraulic calcium silicates, with smaller quantities of calcium aluminates and ferrites. It is produced by the heat treatment of cement raw materials in a kiln. Clinker is pulverized with gypsum in the manufacture of Portland cement. Pozzolan. A siliceous or siliceous and aluminous material which in itself possesses little or no cementitious value but will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to form compounds possessing cementitious properties. (ASTM C340) Pozzolanic. Possessing little or no cementitious value but capable of chemically reacting with calcium hydroxide at ordinary temperatures to form compounds possessing cementitious properties. (ASTM C340) Prehydrate. To mix with water and allow to react or yield in the water before use. Common technique for bentonite. May also be done for convenience in cementing operation to allow mixing of water containing the additives with powdered neat cement. Primary Cementing. The first cementing operation performed to place a cement sheath around a casing or liner. The main objectives include zonal isolation to prevent fluids migration in the annulus, support for the casing or liner and protection of the casing from corrosive fluids. Pumpability. The ability of the slurry to be pumped. Measured by the API thickening time test. Pumping Time. Loosely, the total time required for pumping the cement slurry into the well, plus a safety factor. Pumping time can also be the time to reach a consistency deemed to be unpumpable (generally 70 Bc) during an API thickening time test. Reduced Water Slurries. A cement slurry having a water content less than would normally be used without modifying additives.

Sack. A unit of measure of Portland cement. In the United States the amount which occupies a bulk volume of 1.0 ft3. For most Portland cement, including API classes of cement, a sack is 94 lbm. The sack is the basis for slurry design calculations. Sedimentation. Separation of the components of a cement slurry in which the solids settle. One of characterizations used to define slurry stability. Slurry Density. The weight per unit volume of a cement slurry (usually kg/m3 or lbm/gal). Slurry Yield. The volume of slurry obtained when one sack of cement is mixed with the desired amount of water and other additives (usually m3/kg or ft3/sk). Slurry Stability. The ability of a cement slurry to maintain homogeneity. Two tests are used as a measure of slurry stability; the free fluid and sedimentation. Squeeze Cementing. The forcing, by pressure, of cement slurry into a specified location in a well, such as channels or perforations, for the purpose of achieving isolation. Strength Retrogression. A decline of cement strength at elevated temperatures. This decline is pronounced at temperatures above 110°C [230°F]. It is controlled by the addition of silica to the cement. Sulfate Resistance. The ability of set cement to resist deterioration in the presence of sulfate ions. Sulfate-Resistant Cement. Cement in which the amount of tricalcium aluminate is controlled as specified by API Specification 10A. Tail Cement. The last cement system pumped during primary cementing. It is the cement which covers the lower sections of the well, especially planned completion intervals. Tensile Strength. The force per unit cross-sectional area required to pull a substance apart. Thickening Time. A measurement of the time during which a cement slurry remains in a fluid state and is capable of being pumped. Thickening time is assessed under simulated downhole conditions using a consistometer that plots the consistency of a slurry over time at the anticipated temperature and pressure conditions. The end of the thickening time is considered to be 50 or 70 Bc for most applications. (API RP10B)

Right Angle Set. The characteristic of a cement slurry in which its consistency increases from the point of departure or 30 Bc to 100 Bc in a very short time.


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Glossary

99

Thixotropy. The characteristic of a fluid, such as cement or drilling mud, to develop gel strength over time when not subject to shearing and then to liquefy when agitated. Turbulent Flow. Flow of a fluid characterized by swirling or chaotic motion as the fluid moves along the flow path. This is a preferred flow regime for mud removal during primary cementing. Water-to-Cement Ratio. In a cement slurry, the ratio of water to cement expressed as percent; the parts of water used to mix with 100 parts of cement. Wait on Cement (WOC). The time necessary to wait for cement to develop required strength for the next operation. WOC. See Wait on Cement.

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Marks of Schlumberger Mark

Identifier

ARCTICSET

cement system for use through permafrost

CemCADE

cementing design and evaluation software

CemCAT

cementing computer-aided treatment

CemCRETE

concrete-based oilwell cementing technology

CemNET

advanced fiber cement to control losses

CemSTONE

advanced cement technology

CemSTREAK

rapid deployment cementer

CPS

cement pumping skid

DeepCEM

deepwater cementing solution

DeepCRETE

deepwater cementing solution

DeepSea EXPRES

offshore plug launching system

DensCRETE

slurry system

DESC

design and evaluation services for clients

DuraSTONE

advanced durable cement technology

EXPRES

extrusion plug release system (cementing head)

EZEFLO

surfactant

FLAC

fluid-loss additives for cement

FlexSTONE

advanced flexible cement technology

GASBLOK

gas migration control cement system

i-Handbook

oilfield data handbook

InterACT

wellsite monitoring and control system

KOLITE

cement additive for low-density slurries

LAS

liquid additive system

LiteCRETE

slurry system

LITEFIL

cement additive for low-density slurries

MudCLEAN

chemical wash for removal of drilling mud

MUDPUSH

spacer family for cementing

PERMABLOK

fluid system to permanently plug a zone

PipeView

multifinger caliper tool for PS Platform tool string

PS Platform

new-generation production services platform


■

Marks of Schlumberger

101

Mark

Identifier

RFC

regulated fill-up cement

RST

Reservoir Saturation Tool

SALTBOND

cement system for cementing across salt zones

SCMT

Slim Cement Mapping Tool

SELFSTRESS

expanding cement system

SFM

Solids Fraction Monitor

SFM-C

Process control for cement slurry mixing

ShearSEAL

shear-activated, high-temperature lost circulation fluid

SlimAccess

wireline logging tool for slim and complex geometry boreholes

SlimXtreme

slimhole, high-pressure, high-temperature well logging platform

SLURRY CHIEF

cement mixing equipment

SOS

slurry/oil squeeze

SqueezeCRETE

remedial cementing solutions

ThermaSTONE

chemically stabilized cement for ultrahigh-temperature applications

THIXOLITE

thixotropic low-density cement

TIC

turbulence inducer for cement

TORNADO

cement mixing equipment

UNIFLAC

unified fluid-loss additive

UniMIX

cement slurry system

UNISET

unified retarder

UniSLURRY

cement systems

USI

UltraSonic Imager

Variable Density

cement bond quality

WELBOND

improved bonding cement system

WELLCLEAN

optimal mud removal service

WELLCLEAN II

Engineering Solution

ZONELOCK

permanent zone sealing fluid system

102


TSL-4274

Cementing Catalog

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