API RP 19B 2nd Ed.2006 + A1 & A2.2014 Recommended Practices for Evaluation of Well Perforators

Recommended Practices for Evaluation of Well Perforators

API RECOMM RECOMMENDED ENDED PRACTICE PRACTICE 19B SECOND EDITION, SEPTEMBER 2006 REAFFIRMED, APRIL 2011 ADDENDUM ADDENDUM 1, APRIL APRIL 2014 2014 ADDENDUM ADDENDUM 2, DECEMBE DECEMBER R 2014

Recommended Practices for Evaluation of Well Perforators

Upstream Segment

API RECOMME RECOMMENDE NDED D PRACTI PRACTICE CE 19B 19B SECOND EDITION, SEPTEMBER 2006 REAFFIRMED, APRIL 2011 ADDEND ADDENDUM UM 1, 1, APRIL APRIL 2014 ADDEND ADDENDUM UM 2, 2, XXXX XXXX 2014 2014

SPECIAL NOTES API publications necessarily address problems of a general nature. With respect to particular circumstances, local, state, and federal laws and regulations should be reviewed. Neither API nor any of API’s employees, subcontractors, consultants, committees, or other assignees make any warranty or representation, either express or implied, with respect to the accuracy, completeness, or usefulness of the information contained herein, or assume any liability or responsibility for any use, or the results of such use, of any information or process disclosed in this publication. Neither API nor any of API’s employees, subcontractors, consultants, or other assignees represent that use of this publication would not infringe upon privately owned rights. API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any authorities having jurisdiction with which this publication may conflict. API publications are published to facilitate the broad availability of proven, sound engineering and operating practices. These publications are not intended to obviate the need for applying sound engineering judgment regarding when and where these publications should be utilized. The formulation and publication of API publications is not intended in any way to inhibit anyone from using any other practices. Any manufacturer marking equipment or materials in conformance with the marking requirements of an API standard is solely responsible for complying with all the applicable requirements of that standard. API does not represent, warrant, or guarantee that such products do in fact conform to the applicable API standard. Classified areas may vary depending on the location, conditions, equipment, and substances involved in any given situation. Users of this Recommended Practice should consult with the appropriate authorities having jurisdiction. Users of this Recommended Practice should not rely exclusively on the information contained in this document. Sound business, scientific, engineering, and safety judgment should be used in employing the information contained herein. Information concerning safety and health risks and proper precautions with respect to particular materials and conditions should be obtained from the employer, the manufacturer or supplier of that material, or the material safety data sheet. Where applicable, authorities having jurisdiction should be consulted. Work sites and equipment operations may differ. Users are solely responsible for assessing their specific equipment and premises in determining the appropriateness of applying the Recommended Practice. At all times users should employ sound business, scientific, engineering, and judgment safety when using this Recommended Practice. API is not undertaking to meet the duties of employers, manufacturers, or suppliers to warn and properly train and equip their employees, and other exposed, concerning health and safety risks and precautions, nor undertaking their obligations to comply with authorities having jurisdiction.

All rights reserved. No part of this work may be reproduced, stored in a retrieval system, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission from the publisher. Contact the Publisher, API Publishing Services, 1220 L Street, N.W., Washington, D.C. 20005. Copyright © 2006 American Petroleum Institute

FOREWORD This document is under the jurisdiction of the API Subcommittee on Completion Equipment. Nothing contained in any API publication is to be construed as granting any right, by implication or otherwise, for the manufacture, sale, or use of any method, apparatus, or product covered by letters patent. Neither should anything contained in the publication be construed as insuring anyone against liability for infringement of letters patent. This document was produced under API standardization procedures that ensure appropriate notification and participation in the developmental process and is designated as an API standard. Questions concerning the interpretation of the content of this publication or comments and questions concerning the procedures under which this publication was developed should be directed in writing to the Director of Standards, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005. Requests for permission to reproduce or translate all or any part of the material published herein should also be addressed to the director. Generally, API standards are reviewed and revised, reaffirmed, or withdrawn at least every five years. A one-time extension of up to two years may be added to this review cycle. Status of the publication can be ascertained from the API Standards Department, telephone (202) 682-8000. A catalog of API publications and materials is published annually and updated quarterly by API, 1220 L Street, N.W., Washington, D.C. 20005. Suggested revisions are invited and should be submitted to the Standards and Publications Department, API, 1220 L Street, NW, Washington, DC 20005, [email protected].

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CONTENTS Page

0

SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 0.1 General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 0.2 Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 0.3 API Registered Perforator Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 0.4 Reports and Advertisements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

1

EVALUATION OF PERFORATING SYSTEMS UNDER SURFACE . . . . . . . . . . . . . CONDITIONS, CONCRETE TARGETS1 1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 1.2 Test Target . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 1.3 Perforating System Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 1.4 Charge Selection and Aging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 1.5 Multi-Directional Firing Perforator Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 1.6 Uni-Directional Perforator Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 1.7 Test Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 1.8 Test Results Validity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 1.9 Data Collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 1.10 Data Recording and Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 1.11 Recertifying Published API RP 19B Section 1 . . . . . . . . . . . . . . . . . . . . . . . . . . .6 1.12 Special API RP 19B Section 1Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

2

EVALUATION OF PERFORATORS UNDER STRESS CONDITIONS, BEREA TARGETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 2.2 Berea Sandstone Target . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 2.3 Preparation of Berea Sandstone for the Target . . . . . . . . . . . . . . . . . . . . . . . . . . .15 2.4 Test Apparatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 2.5 Test Conditions and Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

3

EVALUATION OF PERFORATOR SYSTEMS AT ELEVATED TEMPERATURE CONDITIONS, STEEL TARGETS15 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 3.2 Reference Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 3.3 Test Target . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 3.4 Perforating System Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 3.5 Charge Selection and Aging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 3.6 Gun Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 3.7 Clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 3.8 Number of Shots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 3.9 Temperature Environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 3.10 Test Fluid Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 3.11 Temperature Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 3.12 Test Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 3.13 Data Collection and Recording . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 3.14 Pressure Testing of the Gun System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

4

EVALUATION OF PERFORATION FLOW PERFORMANCE UNDER SIMULATED DOWNHOLE CONDITION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24 4.2 Target Preparation and Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25 4.3 Target Evacuation and Saturation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25 4.4 Target Characterization and Permeability Measurement . . . . . . . . . . . . . . . . . . .26 4.5 Testing Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27 4.6 Test Target Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32 4.7 General Perforation Testing Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34 4.8 Systems Calibration and Test Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . .35 4.9 Data Recording . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36 4.10 Liquid Flow Data Reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36 v

CONTENTS Page

4.11 Gas Flow Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39 4.12 Standard Test Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42 5

DEBRIS COLLECTION PROCEDURE FOR PERFORATING GUNS. . . . . . . . . . .45 5.1 Hollow Carrier Perforating Guns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45 5.2 Phase I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45 5.3 Phase II. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46 5.4 Charge Case Debris Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47 5.5 Perforating Systems With Capsule Charges . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

6

EVALUATION OF PERFORATOR SYSTEMS TO DETERMINE SWELL . . . . . .52 6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25 6.2 Shaped Charge Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52 6.3 Perforating System Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52 6.4 Casing Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52 6.5 Testing Fluid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52 6.6 Pre-Test Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52 6.7 Test Setup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53 6.8 Post Test Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53 6.9 Data Recording and Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

7

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

APPENDIX A Figures 1 2 3 4 5a 5b 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

API REGISTERED PERFORATOR SYSTEMS . . . . . . . . . . . . . . . . . . .55

Example Concrete Target . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 Data Sheet—Perforating System Evaluation, API 19B, Section 1 . . . . . . . . . . . . . .7 Dual String Data Sheet Perforating Systems Evaluation . . . . . . . . . . . . . . . . . . . . . .9 Mixed Charges (Short Perforator) Data Sheet Perforating Systems Evaluation . . 10 Mixed Charges (Regular Perforator, Part 1 of 2) Data Sheet Perforating Systems Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Mixed Charges (Regular Perforator, Part 2 of 2) Data Sheet Perforating Systems Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Section 2 Target Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Shooting End Fixture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Vent End and Seal Fixture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Data Sheet—Perforating System Evaluation, API RP 19B Section 2. . . . . . . . . . 20 Schematic Illustration of Steel Target for Elevated Temperature Test. . . . . . . . . . 22 Typical Axial-Flow Permeability Equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Typical Diametral Flow Permeameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Schematic of Typical Testing Equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Typical Radial-Flow Geometry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Typical Axial-Flow Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Productivity Index Data Reduction Graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Axial Gas Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Post-Shot Radial Flow for a Gas Saturated Core . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Section IV Standard Test Data Recording Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Gun Debris Data Sheet for Hollow Carrier Perforating Systems . . . . . . . . . . . . . 48 Gun Debris Data Sheet for Capsule Charge Perforating Systems . . . . . . . . . . . . . 51 Drift Gauge Drawing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Data Sheet—Swell Data for Hollow Carrier Perforating Systems . . . . . . . . . . . . 54

Tables 1 Permissible Variations of Specimen Mold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 2 Casing and Tubing for Use in Test Target . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 3 XXXXX. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Recommended Practices for Evaluation of Well Perforators 0

Scope

0.1

GENERAL

This Recommended Practice describes standard procedures for evaluating the performance of perforating equipment so that representations of this performance may be made to the industry under a standard practice. This document supersedes all previously issued editions of API RP 43. Sections 1 – 4 of this Recommended Practice provides means for evaluating perforating systems (multiple shot) in 4 ways: 1. 2. 3. 4.

Performance under ambient temperature and atmospheric pressure test conditions. Performance in stressed Berea sandstone targets (simulated wellbore pressure test conditions). How performance may be changed after exposure to elevated temperature conditions. Flow performance of a perforation under specific stressed test conditions.

Section 5 of this Recommended Practice provides a procedure to quantify the amount of debris that comes out of a perforating gun during detonation. The purpose of this Recommended Practice is to specify the materials and methods used to evaluate objectively the performance of perforating systems or perforators.

0.2

IMPLEMENTATION

These procedures become effective as of the date of publication.

0.3

API REGISTERED PERFORATOR SYSTEMS

Information on API Registration of perforator systems can be found in Appendix A.

0.4

REPORTS AND ADVERTISEMENTS

Reports, articles, papers, periodicals, advertisements, or similar publications which refer to results from tests conducted according to API RP 19B must not be worded in a fashion to denote that the American Petroleum Institute either endorses the result cited or recommends or disapproves the use of the perforating system described. Use of data obtained under API RP 19B tests in reports, articles, papers, periodicals, advertisements, or other published material shall include, as a minimum, all test configuration data not specified by API RP 19B or left to the verifying company’s choosing by API RP 19B and the average measured results of the test.

1 1.1

Evaluation of Perforating Systems Under Surface Conditions, Concrete Targets INTRODUCTION

The purpose of this section is to describe recommended practices for evaluating perforating systems using concrete targets under multiple shot, ambient temperature, and atmospheric pressure test conditions. Penetration data recorded in API RP 19B Section 1 may not directly correlate to penetration downhole. All Section 1 perforating system tests published shall be valid for a term of 5 years from the date of the test. After 5 years published system test can be recertified as described in 1.11 of this section.

1.2

TEST TARGET

The tests shall be conducted in a concrete target contained within a steel form as illustrated in Figure 1.

1

2

API RECOMMENDED PRACTICE 19B

Casing/tubing

Concrete

Steel containment/form

Figure 1—Example Concrete Target 1.2.1

Target Preparation

Concrete for the target and test briquettes shall be mixed using a cement-sand-slurry consisting of the following: a. 1 part or 94 lb of API Class A or ASTM Type I cement. b. 2 parts or 188 lb ±1% of dry sand. (The sand shall meet API RP 56, Second Edition requirements for 16 – 30 frac sand. The sand shall be stored in a dry location prior to use.) c. 0.52 part or 49 lb ±1% of potable water. d. The ratio of sand to cement shall be between 2.02 and 1.98. The ratio of water to cement shall be between 0.5252 and 0.5148.

1.2.2

Required Documentation

Each distinct quantity of concrete (truckload or similar) used in the preparation of a target must include a written report from the concrete supplier listing the actual amounts of cement, sand, and water used. Quantities shall be reported in the units utilized during the measuring process, with no conversions or adjustments. The testing company shall maintain supporting documentation that the sand complies with API RP 56 for 16 – 30 frac sand. At a minimum, this shall consist of sieve analysis data for all loads of frac sand received by the concrete supplier. The testing company shall maintain supporting documentation that the casing used in the construction of the target meets the reported grade and weight.

1.2.3

Target Configuration

The shape of the outer target form shall be circular and the size determined by the shot pattern and anticipated penetrating capability of the perforating system to be tested. Positioning of the tubing or casing within the target shall be determined by the gun phasing used in the test. For zero-phased perforators, the casing or tubing shall be set in the target form such that a minimum of three inches of the specified concrete composition surrounds the tubing or casing in all directions.

RECOMMENDED PRACTICES

1.2.4

3

FOR EVALUATION OF WELL PERFORATORS

Target Curing Conditions

The target shall be allowed to cure at a temperature within the concrete greater than 32°F (0°C) for a minimum of 28 days. The top surface of the concrete target shall be covered continuously during the entire curing period with a minimum of three inches of potable water. All strength test specimens shall be kept immersed in water at the same temperature as the concrete test target until they are used.

1.2.5

Target Compressive Strength Evaluation

Target compressive strength shall be evaluated using 2-in. cubes (briquettes) made from the same concrete as the target, prepared and tested as prescribed in 1.2.1 through 1.2.5. Prior to or within 24 hours after conducting a test, the briquettes shall be tested and must have an average compressive strength of not less than 5,000 psi.

1.2.5.1

Compressive Strength Evaluation Apparatus

The molds shall not have more than three cube compartments. The parts of the molds when assembled shall be positively held together. The molds shall be made of hard metal, not attacked by the cement mortar, with a Rockwell hardness number not less than 55 HRB. The sides of the mold shall be sufficiently rigid to prevent spreading or warping. The interior faces of the molds shall be plane surfaces and shall conform to the tolerances in Table 1. A base plate having a minimum thickness of 1/4 in. shall be used.

Table 1—Permissible Variations of Specimen Mold Parameter Planeness of side Distance between opposite sides Height of each compartment Angle between adjacent faces1

New

In Use

<0.001 in. 2 in., ±0.005 in. 2 in., +0.01 to –0.005 in. 90, ±0.5°

<0.002 in. 2 in., ±0.005 in. 2 in., +0.01 to –0.015 in. 90, ±0.5°

Note: 1Measured at points slightly removed from the intersection. Measured separately for each compartment between all the interior faces and the adjacent face and between interior faces and top and bottom planes of the mold.

The testing machine shall conform to the requirements in ASTM C 109. The molds shall be checked for tolerances and the testing machine shall be calibrated within ±1% of the load range to be measured at least once every two years.

1.2.5.2

Preparation of Molds

Apply a thin coating of release agent (aerosol lubricant for example) to the interior faces of the mold and contact surface of the base plate. Wipe the mold faces and base plate with a cloth as necessary to remove any excess release agent and to achieve a thin, even coating. Seal the surfaces where the halves of the mold join by applying a coating of light grease. The amount should be sufficient to extrude slightly when the two halves are tightened together. Remove any excess grease with a cloth. After placing the mold on its base plate (and attaching with clamps if applicable), apply grease to the exterior contact line of the mold and base plate to achieve a water tight seal.

1.2.5.3

Placing Slurry in Molds

The slurry sample shall be procured midway during the target pour. For large targets requiring multiple concrete trucks, the sample shall be taken from the truck filling the middle portion of the target. Preparation of the specimens shall begin within 15 minutes of procuring the sample. Stir the slurry by hand using a non-absorbent spatula or puddling rod to minimize segregation. Place slurry in each specimen compartment in the prepared molds in a layer equal to one-half of the mold depth. The slurry shall be placed in all the specimen compartments before commencing the puddling operation. Puddle each specimen 25 times using a glass or noncorroding metal rod approximately 8 in. long by 1/4 in. in diameter. After puddling the layer, the remaining slurry shall again be stirred. Fill the molds to overflowing and puddle as with the first layer. After puddling, the excess slurry shall be struck even with the top of the mold, using a straightedge. Specimens in molds which show evidence of leaking shall be discarded. For one test determination, not less than six specimens shall be prepared.

4


1.2.5.4

Curing of Specimens

As soon as possible, but no more than 2 hours after preparation, the molds shall be placed in the water on the top of the Section 1 target. The top of the Section 1 target must have firmed sufficiently to support the molds. The water level in the top of the target must be kept high enough to completely cover each mold. Within 20 – 23 hours after initial placement, remove the molds from the water, remove the specimens from the molds, and place the specimens in a white, plastic container, filled with potable water. Place the container in the water on top of the Section 1 target, where it shall remain for the entire curing period. The container must be at least 6 in. deep, and the specimens shall remain fully submerged in the water until immediately prior to being tested.

1.2.5.5

Specimen Testing

Wipe each specimen to a surface-dry condition and remove any loose material from the faces that will be in contact with the bearing blocks of the testing machine. Check these faces by applying a straightedge. If there is appreciable curvature, grind the face or faces to plane surfaces or discard the specimen. Apply the load to specimen faces that were in contact with the plane surfaces of the mold. Center the specimen in the testing machine below the upper bearing block. Prior to the testing of each cube, it shall be ascertained that the spherically seated block is free to tilt. The load surfaces shall be clean. Use no cushioning or bedding material. Appropriate safety and handling procedures shall be employed in testing the specimen. a. The rate of loading shall be 16,000 ±1600 lbf (4000 ±400 psi) per minute. Make no adjustment to the controls of the testing machine while a specimen is yielding before failure. b. The compressive strength is calculated by dividing the maximum load in lbf by cross-sectional area in square inches. If deviations of 1/16 inch or more from the specified linear dimension of 2.00 inches are reported, use the actual area for the calculation of the compressive strength. In determining the compressive strength, do not consider specimens that are manifestly faulty. The maximum permissible range between specimens is 8.7% of the average. If this range is exceeded, discard the result that differs the most, and check the range of the remaining specimens. Repeat until the results comply with the maximum permissible range. A minimum of three specimens is required for a valid test. The compressive strength of all acceptable test specimens shall be averaged and reported to the nearest 10 psi.

1.2.6

Casing or Tubing to Be Used in Target

Casing or tubing sizes, weights, and grades to be used in the target are shown in Table 2.

Table 2—Casing and Tubing for Use in Test Target Pipe Size, OD in. 23/8 27/8 31/2 41/2 5 1 5 /2 7 5 7 /8 85/8 95/8 103/4 113/4 133/8

1.3

Pipe Nominal Weight, lb/ft 4.6 6.4 9.2 11.6 15.0 17.0 32.0 33.7 40.0 47.0 51.0 54.0 61.0

Casing or Tubing, API Grade L-80 L-80 L-80 L-80 L-80 L-80 L-80 L-80 L-80 L-80 L-80 L-80 L-80

PERFORATING SYSTEM SELECTION

The perforating system to be tested shall consist of standard field equipment, including a sufficient length of continuously loaded active gun, shot density, phasing, charges, explosive accessories, and other component parts representative of standard field equipment. Selection of the charges must conform to 1.4.



5

Exception: If a debris test is to be conducted concurrently with the Section 1 test, the bottom sub/plug must be solid or blanked off to minimize the sump effect.

1.4

CHARGE SELECTION AND AGING

The required number of charges shall be samples taken uniformly from a minimum production run of 300 charges and packaged in the manufacturing/service company’s standard shipping containers. A minimum production run is a continuous run which may span multiple shifts in order to meet the required minimum quantities. These charges shall be stored for a minimum of four weeks prior to testing to allow some aging to occur. Charges shall be selected from one or more unopened containers.

1.5

MULTI-DIRECTIONAL FIRING PERFORATOR SYSTEMS

For multi-directional firing perforator systems, a sufficient length of continuously loaded active gun shall be tested to provide a minimum of 12 shots or one foot of continuously loaded gun, whichever provides more shots. The perforating device shall be shot as it is normally positioned in the casing.

1.6

UNI-DIRECTIONAL PERFORATOR SYSTEMS

Uni-directional perforator systems, without positioning devices, shall be tested in two positions. In one position, all shots shall be fired at maximum clearance. In the other position all shots shall be fired at minimum clearance. A minimum of 8 shots shall be fired from each position. Perforator systems with positioning devices shall be fired in the position assumed in a well. A minimum of 12 shots shall be fired.

1.7

TEST FLUID

Water shall be used as the test fluid in testing all perforating systems.

1.8

TEST RESULTS VALIDITY

No test shall be considered valid if the average depth of penetration of the concrete target is within three inches of the terminal boundary of the target. Any shots that penetrate the terminal boundary of the concrete target or are within the top 12 inches of the concrete target shall be noted in the reported data, but shall not be counted in averaging the penetration data from the test.

1.9

DATA COLLECTION

The following measurements shall be made for each perforating system evaluated. a. Total penetration depth. b. Casing or tubing hole diameter. c. Burr height. d. Mandatory of a minimum of 6 QC shots. All perforator individual or averaged penetration depths shall be reported to the nearest 0.1 inch.

1.9.1

Total Penetration Depth

The total depth shall be reported as the distance from the original inside wall of the casing or tubing to the end of the perforation tunnel. The end of the perforation tunnel shall be established as that point where concrete material strength damage ends as qualitatively indicated by manual scraping/probing of the exposed material surface.

1.9.2

Casing or Tubing Hole Diameter

The casing or tubing hole diameter shall be measured along the short and long elliptical axes and reported along with the average of the two measurements. Such measurements shall be made from outside the casing or tubing (prior to cutting) with a caliper, whose arms readily pass through the perforation. The short axis shall be the smallest through-hole diameter measured. Casing or tubing hole diameter shall be reported to the nearest 0.01 inch.

6

1.9.3


Burr Height

The maximum protrusion from the inside casing or tubing wall next to the perforation shall be measured and reported as the burr height. If debris from the perforator is lodged in the perforation hole in the casing or tubing and cannot be removed with finger pressure, the total height of such obstruction shall be recorded as burr height and explained. Burr height shall be reported to the nearest 0.01 inch.

1.10

DATA RECORDING AND REPORTING

Data shall be reported on all shots fired or attempted. Data shall be reported in the same order that it was shot ballistically, with #1 being the first charge shot. See Figure 2 for an example data sheet. Any data sheet used must include a similarly positioned watermark indicating that the test is not registered with the API. Comments regarding other gun system configurations should not be included.

1.11 1.11.1

RECERTIFYING PUBLISHED API RP 19B SECTION 1 General

The purpose of this section is to describe test procedures for recertifying published Section 1 system tests with single shot Quality Control testing. Recertification verifies current production charges are representative of results obtained in the original API RP 19B Section 1 test.

1.11.2

Test Configuration

The QC Performance test shall be conducted as defined in the original QC specification that was used in the published system test. The target must meet the original specifications at the time of the published API system test. Compare the QC specifications with the current charge revision against the original QC specifications at time of API test. Current QC specifications must meet or exceed the original QC specifications. If original specifications cannot be met then a full system test must be performed, per API RP 19B Section 1.

1.11.3

Charge Selection

The required number of charges shall be samples taken uniformly from a minimum continuous production run of 300 charges as per Section 1.4. Charge selection from inventory must be produced in the last 12 months.

1.11.4

QC Performance Test

A minimum of 6 valid QC test shots shall be made. No test shot shall be considered valid if the depth of penetration of the QC target is within three inches of the terminal boundary or exits the side of the target.

1.11.5

Recertification Criteria

Only systems where the average results of all valid test shots meet or exceed 90% of the original QC specification performance that was used in the published system test will be recertified. In the case where the same charge is used in multiple systems, only one series of QC testing is required. Each individual system must be reviewed and recertified.

1.11.6

Data Collection

The following measurements shall be made for each QC shot evaluated: a. Total penetration depth. b. Hole diameter in the casing, tubing, or steel plate simulating them. All perforator individual or averaged penetration depths shall be reported to the nearest tenth of an inch. Hole diameter shall be reported to the nearest hundredth of an inch.

8


1.11.7

Total Penetration Depth

The total depth shall be reported as the distance from the original inside wall of the casing, tubing, or steel plate to the end of the perforation tunnel. The end of the perforation tunnel shall be established as that point where target material strength damage ends as qualitatively indicated by manual scraping/probing of the exposed material surface.

1.11.8

Casing, Tubing or Steel Plate Hole Diameter

The casing, tubing, or steel plate hole diameter shall be measured along the short and long elliptical axes and reported along with the average of the two measurements. Such measurements shall be made from outside the casing, tubing, or steel plate with a caliper, whose arms readily pass through the perforation. The short axis shall be the smallest through-hole diameter measured.

1.12

SPECIAL API RP 19B SECTION 1 TESTS

Well environments may require that special tests be conducted to better simulate downhole conditions. Some conditions require special casing. In some cases even dual string casing, is placed over a producible zone. In other situations gas environments may require the use of special gun systems. Operators must be able to evaluate perforating systems under these conditions with special tests. This section provides a means to shoot and publish a witnessed test in a Special API RP 19B Section 1 Target, with any or all of the following exceptions. 1. 2. 3. 4.

Special casing may be used. Dual string casing may be used. The gun may be shot with air instead of water in the gun to casing annulus. The gun may be loaded with mixed charges (two different names of charges loaded into one gun.)

All other API RP 19B Section 1 requirements must be met. All exceptions must be listed in the remarks section of the appropriate data sheet (see Figures 2 or 3). For the mixed systems, all other API RP 19B Section 1 requirements must be met. All exceptions must be listed in the remarks section of the appropriate data sheet (see Figures 4, 5a, or 5b.) See Sections 1.12.1 – 1.12.6.5 for details on mixed systems evaluation. Casing annulus material should be RP 19B cement unless otherwise specified by the customer. Single string tests must be reported on the Special Test form provided by API. See Figure 2. Dual string test must be reported on the Special Dual String Test form also provided by API. See Figure 3. Mixed perforating system tests must be reported on the Special Test form provided by API. See Figures 4, 5a, or 5b.

1.12.1

Mixed Charge Perforating System Selection

The mixed charge perforating system to be tested shall consist of standard field equipment, including a sufficient length of continuously loaded active gun, shot density, phasing, charges, explosive accessories, and other component parts representative of standard field equipment. Selection of the charges must conform to 1.4 for each charge name (a minimum production run of 300 charges is required for each charge name).

1.12.2

Multi-Directional Firing Mixed Charge Perforator System

For multi-directional firing mixed perforator systems, a sufficient length of continuously loaded active gun shall be tested to provide a minimum of 12 shots or one foot of continuously loaded gun, whichever provides more shots. A minimum of six shots of each charge name shall be fired. The perforating device shall be shot as it is normally positioned in the casing.

1.12.3

Uni-Directional Firing Mixed Charge Perforator System

Uni-directional mixed charge perforator systems, without positioning devices, shall be tested in two positions. In one position, all shots shall be fired at maximum clearance. In the other position all shots shall be fired at minimum clearance. A minimum of 8 shots shall be fired from each position. A minimum of four shots of each charge name shall be fired. Perforator systems with positioning devices shall be fired in the position assumed in a well. A minimum of 12 shots shall be fired. A minimum of six shots of each charge name shall be fired.


1.12.4


13

Test Fluid, Test Result Validity, Data Collection

Requirements defined in Sections 1.7, 1.8, and 1.9 shall apply.

1.12.5

Data Recording and Reporting

Data shall be reported on all shots fired or attempted. Data shall be reported in the same order that it was shot ballistically, with #1 being the first charge shot. See Figures 4, 5a, and 5b for an example data sheet. Data sheet reflected in Figure 4 can be used for reporting results of up to 12 shots fired. Data sheet illustrated in Figure 5 can be used for reporting results of more than 12 shots fired. For reporting results of more than 24 shots fired, multiple data sheet, i.e. three-sheet reports, can be used. Any data sheet used must include a similarly positioned watermark indicating that the test is not registered with the API. Comments regarding other gun system configurations should not be included.

1.12.6 1.12.6.1

Recertifying Published API RP 19B Section 1, Clause 1.12.1 Tests General, Test Target

Requirements defined in Sections 1.11.1 and 1.11.2 shall apply.

1.12.6.2

Charge Selection for the Mixed System

The required number of charges shall be samples taken uniformly from a minimum production run of 300 charges for each charge name as defined in 1.4. Charge selection from inventory must be produced in the last 12 months.

1.12.6.3

QC Performance Test for the Mixed System

The QC Performance test shall be conducted as defined in the original QC manufacturer specification that was used in the published system test. A minimum of 6 QC test shots for each charge name shall be made. No test shot shall be considered valid if the depth of penetration of the QC concrete target is within three inches of the terminal boundary or exits the side of the concrete target.

1.12.6.4

QC Test Results Validity, Data Collection, Total Penetration Depth

Requirements defined in Sections 1.11.5, 1.11.6, and 1.11.7 shall apply.

1.12.6.5

Casing, Tubing or Steel Plate Hole Diameter

The casing, tubing, or steel plate hole diameter for each of two QC sets (a minimum of 6 QC shots for each charge name) shall be measured along the short and long elliptical axes and reported along with the average of the two measurements. Such measurements shall be made from outside the casing, tubing, or steel plate with a caliper, whose arms readily pass through the perforation. The short axis shall be the smallest through-hole diameter measured. Casing, tubing, or steel plate hole diameter shall be reported to the nearest 0.01 inch. Since the mixed perforating system will be fired from one device, the casing, tubing, or steel plate material used for each of the two QC sets firing shall be the same. All perforator individual or averaged penetration depths shall be reported to the nearest 0.1 inch.

2 2.1

Evaluation of Perforators Under Stress Conditions, Berea Targets INTRODUCTION

This section is intended to provide a test procedure to be followed for measuring perforator performance in stressed Berea sandstone with wellbore pressure applied.

2.2

BEREA SANDSTONE TARGET

Tests will be conducted using Berea sandstone targets mounted as shown in Figure 6. Berea sandstone target material shall have a bulk porosity of not less than 19% nor more than 21%.

14


Stressing fluid inlet Core Vent

1 in. NPT nipple

Threaded rod

Vent end support plate (refer to Figure 8)

Vent and seal plate (refer to Figure 8)

4 in. or 7 in. Diameter core (refer to Section 2.3.1)

1

/4 in. Thick rubber sleeve

3

/4 in. Hydrostone®* spacer

Shooting end target plate (refer to Figure 7)

Shooting end support plate (refer to Figure 7)

12 in. Minimum diameter vessel

Not to Scale

* Trade name of U.S. Gypsum Co., Chicago IL. This term is used as an example only, and does not constitute an endorsement of this product by API.

Figure 6—Section 2 Target Configuration


2.3 2.3.1


15

PREPARATION OF BEREA SANDSTONE FOR THE TARGET Size

For charges 15 grams or less, a 4-inch (±3%) diameter core will be cut from a large block of Berea sandstone. For charges exceeding 15 grams, a 7-inch (±3%) diameter core will be cut from a large block of Berea sandstone. Depending on the expected perforation depth, the total length of the core shall approximate 12, 15, 18, 21, 24, or 27 inches, measured to within ±0.25-inch. The test will be considered valid if at least 3 inches of unpenetrated core remains.

2.3.2

Cutting

The core may be lathe turned or cut with a core barrel.

2.3.3

Drying

The cut and sized core shall be dried at least 24 hours, or to constant weight in a ventilated oven maintained at 200°F, but not above 210°F.

2.3.4

Evacuation

The core shall be evacuated in an airtight chamber provided with a suitably sized evacuation port and pump. There shall also be provided a means of admitting the saturating liquid slowly to the bottom of the chamber in order that the core can be covered with the liquid from the bottom to its top while under vacuum. The core shall be evacuated to a pressure of 1 millimeters of mercury or less for a minimum of 6 hours before admitting the saturating fluid. The saturating fluid shall not be admitted at a rate faster than the capillary rise of the fluid in the core.

2.3.5

Saturation

The saturating liquid shall be 3% (by weight) sodium chloride brine (specific gravity to be measured at ambient temperature to the nearest thousandth) prepared from sodium chloride and distilled or deionized water. The 3% brine solution shall be evacuated under medium to low vacuum (50 mm Hg pressure) for 30 minutes before use in order to remove dissolved gases, but not enough to increase the salt concentration appreciably. After the core is flooded in the evacuation chamber, vacuum (60 mm Hg pressure or lower) is to be maintained for 2 hours, after which the pressure is to be slowly increased to atmospheric pressure. The restoredstate core should be kept stored under the 3% brine until porosity determinations are made. Kerosene may be substituted for the 3% sodium chloride brine.

2.3.6

Porosity Determination

After saturation, the core shall be wiped lightly to remove free brine from the surface and weighed immediately. The porosity shall be calculated by the following formula:

Φ = (V pV b) (100)

(2-1)

The pore volume, V p, shall be calculated by dividing the difference in weight in the saturated and dry states by the density of the 3% brine. The bulk volume, V b, shall be calculated from physical measurements of each individual core. The weight shall be determined at room temperature on scales with a precision of 1 gram for loads of 1,000 grams or more.

2.3.7

Core Storage

Cores shall be stored in the 3% brine during the interval between obtaining the core characteristics and shooting operations.

2.4 2.4.1

TEST APPARATUS Rubber Sleeve

For charges 15 grams or less, the sleeve shall have an internal diameter of 4 inches and a wall thickness of 0.25 inch. For charges larger than 15 grams, the sleeve shall have an internal diameter of 7 inches and a wall thickness of 0.25 inch.

16

2.4.2


Target End Fixtures

The shooting end fixture shall contain a mild steel faceplate 0.38 inch thick cut from ASTM A 36 grade steel and a 0.75 inch thick Hydrostone ®1 spacer. The 0.75 inch Hydrostone ® spacer may be poured in place or prepared separately at the discretion of the tester. Hydrostone® must be used in accordance with the manufacturer’s instructions. Refer to Figure 7 for details of the shooting end fixture and Figure 8 for details of the vent end fixture.

2.4.3

Vent Tube

The vent tube shall be a nominal 1-inch outside diameter NPT steel tube with a minimum inside diameter of 0.25 inch.

2.4.4

Pressure Vessel

The minimum inside diameter of the pressure vessel shall be 12 inches. Suitable pressure sensing and remote recording equipment shall be used to obtain a permanent record of the pressure profile for the complete test. All equipment must be calibrated against a suitable reference standard at intervals not exceeding six months.

2.4.5

Mounting of Core Target

The gun shall be sufficiently secured to the core target to assure correct clearance and alignment. If bolts are used to hold the shooting end fixture and vent tube end fixture to the core, the end fixture must be free to travel in the direction of the core so as to transmit the stress uniformly. The entire target shall be centralized (±1.0 inch) in the shooting vessel (refer to Figure 6).

2.4.6

Perforating Tool

The tool to be tested will be a single-shot section of the gun. This gun section must be a duplicate of the field gun.

2.5 2.5.1

TEST CONDITIONS AND PROCEDURE Chamber Fluid

The chamber fluid shall be water and maintained at ambient temperature throughout the test.

2.5.2

Clearance

With the exception of zero-phased perforators used with eccentering devices, bullet and jet perforators shall be tested at a clearance of 0.5 inch. Zero-phased perforators used with eccentering devices shall be tested at the clearance assumed in a well.

2.5.3

Charge Selection and Aging

The required number of charges shall be samples taken uniformly from a minimum production run of 1000 RDX or PETN charges (a production run of only 300 charges is required for high temperature explosives) and packaged in the manufacturing/ service company’s standard shipping containers. These charges shall be stored for a minimum of four weeks prior to testing to allow some aging to occur.

2.5.4

Number of Shots

Tests are to consist of a minimum of three shots made under stated conditions. Test shot results must be indicative of average performance performance expected expected from productio production n charges. charges.

2.5.5

Firing Pressure

The pressure vessel will be pressured to 3,000 psi. The system will be held static for 5 minutes before shooting to check for leaks. If the core is fully saturated there should be a small fluid flow initially from the vent tube, until stress equalization occurs. The perforating perforating gun is fired fired with a closed system. system. The The pressure pressure gauges gauges and pumps pumps are thus protected protected from from the shock shock of firing. firing. 1This term is used as an example only, and does not

constitute an endorsement of this product by API.


17


63 4 in. or 7 in. 0.03 in. Diameter

0.38 in. 0.01 in.

Target Pl ate Material: Mild Steel ASTM-36

3.0 in. Minimum

9.5 in. 0.5 in. Diameter

3.0 in. Minimum eccentering gun length

0.50 in. 0.02 in.

Support Plate

Figure 7—Shooting End Fixture

Not to Scale

18


4 in. or 7 in. 0.015 in. Diameter

63

1.0 in. NPT

1.25 in. 0.25 in.

End Seal Plate Material: Alum. 6061.T6

Optional

1.5 in. Maximum



Support Plate Material: Alum. 6061.T6

Figure 8—Vent End and Seal Fixture

Not to Scale


2.5.6


19

Determination of Depth of Penetration

The depth of penetration shall be determined by the maximum depth from the exterior steel face plate to the end of the perforation tunnel, as determined by probing for weakened rock beyond the perforation tip.

2.5.7

Faceplate Hole Diameter

The hole diameter shall be measured along the short and long elliptical axes and reported along with the average of the two measurements. Such measurements shall be made from outside the faceplate with a caliper, whose arms readily pass through the perforation. The short axis shall be the smallest through hole diameter measured. Hole diameter shall be reported to the nearest 0.01 inch.

2.5.8

Control of Perforation End Position in Target

In 4-inch diameter targets, the perforation tip must be within 1.25 inches of the centerline of the core for the test to be considered valid. In 7-inch diameter targets, the perforation tip must be within 2.0 inches of the centerline of the core for the test to be considered valid.

2.5.9

Recording of Data

Data from tests performed under Section 2 of API RP 19B, shall be reported. See Figure 9 for an example data sheet. Any data sheet used must include a similarly positioned watermark indicating that the test is not registered with the API. Comments regarding other gun system configurations should not be included.

3 3.1

Evaluation of Perforator Systems at Elevated Temperature Conditions, Steel Targets INTRODUCTION

The purpose of this test is to evaluate perforating systems at elevated temperature and atmospheric pressure. Systems employing any type explosive may be evaluated by this method. The test is conducted at temperature, with atmospheric pressure external to the gun to evaluate explosive system reliability, and utilizing steel as the target material. Separate tests are conducted at temperature, pressure, and time to verify the operational rating of the system. This is intended as a procedure to be followed for a special test.

3.2

REFERENCE DATA

A reference charge test shall be conducted at atmospheric pressure and ambient temperature employing the steel target and the test described herein.

3.3

TEST TARGET

Tests shall be conducted with a laminated target consisting of mild-steel (ASTM A36) flat plates, 1 inch thick with a faceplate 3/8 inch thick. Cross sectional area of the plates shall be chosen for repeatable data collection. Typical target configuration is shown in Figure 10. The target thickness must be at least 0.5 inch greater than the average penetration depth recorded.

3.4


The perforating system to be tested shall consist of the gun associated hardware, and firing head. Production equipment (or specially modified hardware to the same specification) shall be utilized, including gun body, adapters, transfer subs, and explosive components. The free volume to explosive load ratio must be the same or less than a fully loaded field configuration gun: or previously established in a separate test by firing a minimum of one charge after holding at time and temperature at an equal or lower free volume to explosive load ratio for this explosive. For tubing conveyed systems, at least one transfer must be demonstrated on the same or a separate test utilizing a production transfer sub. At least one charge shall be fired subsequent to the transfer. For wireline conveyed systems, any electrical or mechanical switches shall be included if recommended by the service company for this application, unless previously qualified in a separate test.


3.5


21

CHARGE SELECTION AND AGING

The required number of charges shall be samples taken uniformly from a minimum production run of 1000 RDX or PETN charges (a production run of only 300 charges is required for high temperature explosives) and packaged in the manufacturing/ service company’s standard shipping containers. These charges shall be stored for a minimum of four weeks prior to testing to allow some aging to occur.

3.6

GUN CONFIGURATION

Hollow carrier perforating guns must have pressure-tight enclosures on both ends and must be sealed during full duration of the test.

3.7

CLEARANCE

The gun-to-target clearance for all perforating systems shall be zero inches from the outside diameter of the gun body.

3.8

NUMBER OF SHOTS

For statistical purposes a minimum of six shots shall be fired in the heated gun and the reference gun.

3.9

TEMPERATURE ENVIRONMENT

Tests shall be conducted at elevated temperature and atmospheric pressure using the following procedures: a. The shots shall be made at temperature (±10°F) after the perforating system has been exposed to the rated temperature for the rated time period, which is one hour for wireline application, or a minimum of 100 hours for tubing conveyed application. b. The perforating system shall be brought to the rated elevated temperature at a maximum rate of six degrees per minute. c. Average temperature of the test assembly shall be controlled to ±10°F during the exposure period. Fluctuations out of this range are allowable if the time out of the envelope is less than 10% of the total exposure time. Actual average temperature shall be reported.

3.10

TEST FLUID ENVIRONMENT

The reference test (refer to 3.2) and elevated temperature test shall be similarly conducted in air or an appropriate liquid environment, at the option of the testing company. A continuous fluid media shall be used to transfer heat to the gun.

3.11

TEMPERATURE MONITORING

The temperature of the outer surface of the perforating gun adjacent to the top and bottom shot shall be separately monitored by intimate contact throughout the course of the test. The thermocouple shall be accurately shielded to ensure accurate surface gun body temperature. Suitable thermal sensing and remote recording equipment shall be used to obtain a permanent record of the temperature profile for the complete test. All equipment shall be calibrated and certified on a regular basis.

3.12

TEST ASSEMBLY

The method used to mount the steel targets to the perforating system shall be at the option of the testing company.

3.13

DATA COLLECTION AND RECORDING

The following measurements shall be made for each perforating system evaluated: a. Total depth. b. Faceplate hole diameter. c. Faceplate hole roundness.

3.13.1

Total Depth

The total depth shall be measured as the distance from the inside faceplate of the target to the farthest point penetrated by the shaped charge perforating system. The penetration shall be measured to the nearest 0.01 inch. The data shall be expressed as a ratio of the average hot/cold penetration.

22


2 in. x 2 in. x 1 in. Mild steel plate

Perforating gun

Tack weld

2 in. x 2 in. x 3/8 in. Mild steel plate

Side View

Not To Scale

Top View

Figure 10—Schematic Illustration of Steel Target for Elevated Temperature Test


3.13.2


23

Faceplate Hole Diameter

The faceplate hole diameter shall be measured on the inside 3/8-inch faceplate of the target along the short and long elliptical axes of the hole. Both the minimum and maximum shall be expressed as a ratio of the average hot/cold faceplate diameter hole. Such measurements shall be made with a caliper, the arms of which will readily pass through the perforation. Faceplate hole diameter shall be measured to the nearest 0.01 inch.

3.13.3

Faceplate Hole Roundness

The faceplate hole diameter roundness shall be reported as the average maximum faceplate hole diameter divided by the average minimum faceplate hole diameter. This ratio shall be calculated for both hot and cold shots.

3.13.4

Extra Shots

The testing company may test more than the minimum number of charges to obtain a more accurate statistical distribution of test results, but data from all charges tested in any test conducted under API RP 19B, Section 3, shall be reported.

3.14

PRESSURE TESTING OF THE GUN SYSTEM

A separate test shall be made to verify the pressure/temperature/time rating of the gun system. No explosives are required to be in the gun system at this time.

3.14.1

Test Requirements

The test must be made in a suitable pressure vessel with provisions for pressure, temperature. and time chart recorders. Gauges should be calibrated and certified on a regular basis. Materials for the gun system are to satisfy engineering design and quality control specifications as to metallurgy, chemical composition, physical properties, and dimensional properties. Gun body length shall have a minimum unsupported section of eight diameters of nominal outside diameter. If filler bars are used they must have a maximum outside diameter at least 0.25 inch smaller than the inside diameter of the gun. Seal dimensions are to be adjusted to maximum extrusion gap for the test unless all seal configurations represented in the system have been separately and identically qualified.

3.14.2

Minimum Test Conditions

3.14.2.1 Pressure: At the adjusted pressure test value (±500 psi) (refer to 3.14.3) with a minimum test pressure of 1.05 times the operational pressure rating. 3.14.2.2

Temperature: At the operational temperature rating (±10°F).

3.14.2.3 Duration: One hour at the adjusted pressure test value and operational temperature rating for gun bodies; maximum time rating at adjusted pressure test value and operational temperature for seals. 3.14.3

Determination of Adjusted Pressure Test Value

Compute the collapse of the gun body to be actually tested utilizing those parameters required by recognized engineering practice. Compute the collapse of the gun body at “minimum material conditions” (MMC) utilizing specified physical and dimensional properties. Compute the adjusted test pressure as follows: C A × P r P ATV = ----------------C MMC

(3-1)

where P ATV = Calculated adjusted pressure test value to which a specific gun sample is subjected that is equivalent to worst case conditions (minimum material conditions of physical properties, dimensions, and seals), taking into consideration the applicable manufacturing or service company’s safety factor, psi. C A = Calculated collapse value (or failure) of an actual gun specimen to be evaluated based on its measured (actual) physical properties, dimensions, and seals, psi. (For example, the calculated collapse value for a specific gun

24


specimen may be 24,500 psi, however, this value could drop as low as 21,000 psi under minimum material conditions on other production runs.) P r = Operational pressure rating, the maximum to which the gun should be subjected in field service, psi. (This value is related to C MMC by the manufacturing or service company’s assigned safety factor. For example, for a gun rated at 20,000 psi, the C MMC , is 21,000 psi, providing the safety factor is 1.05.) C MMC = Calculated collapse value (or failure) of a hypothetical gun sample under worst case conditions or “minimum material conditions” (MMC) of physical properties, dimensions, and seals, as permitted by design specifications and engineering drawings, psi. (If C MMC for a gun sample with lowest permissible tensile strength, minimum permissible wall thickness, and maximum permissible seal gap is calculated to be 21,000 psi, it has an assigned operational pressure rating ( P r ) of 20,000 psi providing the safety factor is 1.05.) Note: Using the information in the foregoing examples the adjusted pressure test value, PATV, would be calculated as follows:

C A × P r P ATV = ----------------C MMC 24,500 × 20,000 P ATV = ---------------------------------------= 23,333 psi 21,000

3.14.4

Alternate Procedure for Verification of Adjusted Pressure Test Value

Where the computed collapse value is deemed not reliable, a gun body or minimum of six expendable charge cases shall be prepared and tested with materials taken uniformly from production run mill stock and verified or prepared to meet minimum physical and dimensional properties. The gun body or expendable charge cases should be verified or prepared to meet minimum material conditions on all dimensions by careful machining with reference to the applicable engineering specifications. Tolerances for minimum material conditions shall be ±0.001 inch. The gun body or expendable charges shall then be tested at a minimum test pressure of 1.05 times the operational pressure rating.

3.14.5

Disposition of Test Data

Details of test data and corresponding specifications and quality control documentation should be retained by the manufacturer as long as the subject equipment is in field service.

4

Evaluation of Perforation Flow Performance Under Simulated Downhole Condition

4.1 INTRODUCTION The purpose of Section 4 is to provide a basis for the comparison, development, and evaluation of perforators and perforating performance in general through the use of tests looking at the flow performance of perforations shot into rock cores, shot under in situ conditions. The intent of this section shall be to ensure that all entities performing such tests do so in a way that translates improved lab performance into increased performance in the field. This section should NOT be used as a restriction on how a facility is set up and operated. This is best left to the groups performing such tests and allows for designs to be based on experience, best practices, and improvements in technology. The outline for a “standard test” that should be performed by all entities and parties that choose to perform such tests is also included. The structure of this section shall be as follows: a. b. c. d.

a basic target preparation and constructions technique specification; a basic equipment and technique specification highlighting common test artifacts for consideration; standard qualification test description(s), including core saturation procedures; and minimum requirements for comparative tests.


4.2


25

TARGET PERPARATION AND CONSIDERATIONS

4.2.1 Tests shall be conducted using cylindrical natural rock targets, obtained from stone quarries, field outcrops, or from well core obtained from an oil or gas well. 4.2.2 Targets may be cut either perpendicular or parallel to the natural bedding planes in the stone. The choice of bedding plane orientation has implications for test boundary conditions and for data reduction. 4.2.3 The size of the test core shall be at the discretion of the testing company. In general, for charges with 15 gm of high explosive or less, a 4 in. diameter core may be used. For charges with explosive loads greater than 15 gm, a 7 in. target should be used. This is not a strict limit. In many cases useful information can still be obtained for larger charges in smaller cores. The appropriate target size is dependent upon: the charge to be used, the rock strength, rock confinement pressure, and fluid system stiffness. 4.2.4 If necessary, a composite target may be constructed from small diameter field core and some outer shell material in order to create a larger effective diameter. The methodology for doing this shall be at the discretion of the testing company; however, in general these methods will increase experimental uncertainty and may create an indeterminate boundary condition. 4.2.5 Targets can range from 4 in. to 20 in. diameter. Current sizes in use are: 4 in., 5 in., 6 in., 7 in., 9 in. 11.5 in., and 15.5 in. In general, a lab facility can accommodate most testing requirements with three core sizes, ranging from 4 in. diameter to 9 in. diameter. Increased core diameter can reduce experimental variation. 4.2.6 Core length should be sufficient such that end effects do not influence penetration depth or flow measurements. One core diameter is the minimum required distance between the tip of the perforation and the end of the core, and more may be required. Extra core length can reduce experimental variation. 4.2.7 Target dimensions are to be ±0.1 in. for both OD and length. The ends of the core are to be flat and parallel to each other to avoid error. 4.2.8 The rock targets should be initially free of any visible crack or flaws. A crack to the OD boundary may cause experimental error. Also note that cracks visible on a core AFTER testing are common. These cracks may or may not have caused experimental error. Cracks which have visible charge debris inside them most likely were formed during the perforation event. These cracks may also propagate after removing stress from the core and may or may not contribute to experimental error. 4.2.9

In a given comparative study, target diameter and length should be held constant to not add additional error into the result.

4.2.10 Diamond core barrels and saws are preferred for cutting of round cores to reduce fines that may affect core permeability measurements. This effect is increased for radial flow test configurations. Loose material should be brushed off or otherwise removed. 4.2.11 The cut and sized cores shall be oven drie d for at least 24 hr and to a constant weight ( mass change of 1 gm or less in a 24 hr period) in a ventilated oven that is maintained at 200 °F but not higher than 210 °F. 4.3

TARGET EVACUATION AND SATURATION

4.3.1 Target saturation can be single phase (water, oil, or gas) or multi-phase (water-oil, water-gas, oil-gas, or water-oil-gas). Single-phase saturation may simplify tests and in some cases may more closely simulate the near wellbore region due to drilling and completion operations. Multi-phase saturation may more closely simulate the virgin or flowing reservoir or those situations where there are no issues from drilling and completions. Saturation state can affect the geometry of the perforation tunnel. The typical fluids used for single-phase core saturation are odorless mineral spirits (OMS), brine water (3 % KCl), or an inert gas (nitrogen). For safety reasons, one shall not use an oil that contains an aromatic fraction (live crude oil) or a combustible gas (methane or other hydrocarbon). The typical fluids used for multi-phase saturation are brine water, followed by OMS or gas. 4.3.2 Just prior to placement in the evacuation chamber, the rock core should be weighed on a scale with suitable accuracy and range to determine the dry weight of the core. The core shall be evacuated inside of an air-tight chamber provided with a suitably sized evacuation port and vacuum pump to a level of 1 mm of mercury or less for a minimum of 6 hr before admitting any saturating fluid. Lower porosity or lower permeability rocks may require additional evacuation time and/or additional procedures to ensure that the rock core will be adequately saturated. 4.3.3 The core shall be saturated by slowly admitting the saturating fluid into the bottom of the chamber with the core actively maintained at constant vacuum. Care shall be taken to allow the fluid to be imbibed or "wicked" into the core. Under no circumstances should the liquid level be allowed to rise over the saturation line visible on the core OD. After the core is

26


completely saturated, vacuum should be maintained for a minimum of two additional hours, after which the pressure is slowly increased to atmospheric at constant rate over a period of 10 minutes.

4.3.4 After saturation is complete, the core shall be immediately wiped free of loose liquids and weighed again to obtain the saturated weight. The porosity of the core shall be calculated using the following formula:

Φ = ( V p ⁄ V b ) × 100 %

(4-1)

4.3.5 The pore volume V p shall be calculated by dividing the difference in weight in the saturated and dry states by the density of the saturating fluid. The bulk volume V b shall be calculated from the physical dimensions of each individual core. The core weights shall be determined at room temperature with a scale with a precision of 1 gm for loads of 1000 gm or greater. 4.3.6 If the core is to be saturated with a second phase, the core shall be placed under confining stress in a vessel resembling a Hassler sleeve permeameter. The confinement stress level and pore pressure should match the conditions planned for the core when tested. While under stress, a second fluid shall be flowed axially into one end of the core, displacing the first fluid. Flow at a rate that does not exceed the differential pressure level required to cause non-Darcy flow or movement of the fines or clay particles in the pore throats, and continue at this rate until the differential pressure for a given rate is constant or steady state. All cores that will be used in a common test program should be flowed at the same conditions to try and produce an irreducible saturate state to the first fluid that is constant between cores. Some consideration should be given to the gravity effects should the second fluid differ in density from the first, and it may be preferable to inject fluid from the vertical top of the core, the bottom of the core, or both. 4.3.7 After saturating, cores shall be stored in the fluid used to saturate it with, or last flowed through it, until ready for characterization. 4.3.8 After core characterization has occurred, the core shall be stored in the fluid last flowed through the core, until it is ready for use in a perforating experiment. 4.4 4.4.1

TARGET CHARACTERIZATION AND PERMEABILITY MEASUREMENT General

Natural rock targets are at this time the best available option for this type of simulation. A significant disadvantage to these targets is the variability between sample sets, although consistency within a given sample set can be very good. Poor quality targets can be a source of considerable experimental error. Target selection and characterization therefore play a critical role in order to reduce experimental variation. Target characterization includes permeability, porosity, density, and dimensional properties, as well as mechanical properties such as compressive strength, etc. In a given sample set, it is best practice to evaluate a larger sample of targets than required and then cull targets that fall outside of the normal property range for the sample set.

4.4.2

Permeability Measurement

Sample permeability measurement requirements strongly depend on the type of final flow performance evaluation technique and may vary depending upon the rock used and the information desired from the test program. Sufficient measurements of pressure drop, flow rate, and viscosity or temperature should be collected in order to calculate the measures of flow performance as defined in Sections 4.10 or 4.11. For test programs where the final flow performance is desired to be productivity ratio (PR), samples are recommended to be oriented with bedding planes parallel to the long axis of the core. In this case, the axial permeability shall be measured. Convergent flow measurements may also be taken in order to provide information in a strongly heterogeneous rock. Figure 11 demonstrates a typical axial flow boundary condition setup applicable for permeability measurement. The target is configured with a constant pressure boundary condition on each end of the core and a no flow boundary condition on the core OD. This is best accomplished with a flexible jacket on the core OD and a flow distributor on each end of the core. Concentric ring distributors are recommended. Distributor design should be such that local stress and flow restriction effects are minimized. Screen may be used in conjunction with the flow distributors in order to minimize local effects of the distributors. Convergent flow measurements are acquired in a setup similar to that shown in Figure 11, with the exception that a restriction plate is added to the outlet end of the core. The restriction plate should incorporate a sealing gasket in order to restrict the flow to



27

a central opening. The diameter of the restriction hole should be such that the ratio of the open area to the area of the core face is approximately 1:50. For example, the appropriate diameter for a 5 inch diameter core shall be 0.75 inch, and the appropriate diameter for a 7 inch diameter core shall be 1.00 inch. For test programs where the final flow performance is desired to be core flow efficiency (CFE), samples are recommended to have bedding planes perpendicular to the long axis of the core. In this case, both the axial permeability, and the diametral permeability in two orthogonal directions shall be measured. Figure 12 illustrates a typical diametral permeability measurement setup. The core is configured with a constant pressure boundary condition on two opposite 90 degree arcs of length L', and a no flow boundary condition on all other surfaces of the core. The ratio of L' to the total length of the core affects the calculation of cross diameter permeability as shown in Section 4.10.1. In general the length of L' should be at least the length of the expected perforation tunnel. The annular gaps between the sample jacket and core OD shall be filled with a stress transmission media with permeability at least 100 times greater than the expected permeability of the test core. In most cases, steel rods or a high strength proppant can provide this capability. The ends of the core must be sealed to ensure that all flow passes across the diameter of the core. There are several ways to accomplish this, and it is left to the discretion of the testing company to select a method and then do the required testing to assure that there is no leakage. These recommendations will produce conservative results, reduce experimental error, and emphasize the high permeability characteristics of the target. The methods for performing these measurements shall be at the discretion of the testing company except for the following. a. The measurement should be performed under the same effective stress and pore pressure as that used to evaluate the perforated core. b. In general, the measurement should be performed under the same effective stress as that used during the perforation test. c. The core should be at the same fluid saturation condition as that used during the perforation test, and the same fluid and range of flow rates should be used in both tests during the flow measurements. d. Care shall be taken to reduce sources of error as listed in 4.6.

4.4.3

Mechanical Properties

Mechanical properties may vary from core lot to core lot and sometimes target to target. Many times there are visual clues to varying mechanical properties. Permeability, porosity, and density may also provide an indication of significant difference. It is nevertheless good practice to measure various properties of each incoming lot, such as unconfined compressive strength, confined compressive strength, grain size distribution, mineralogy, and pore throat diameter. In recent years, scratch index testing has emerged as a means of quantifying unconfined compressive strength of each sample to be tested. Evaluating the mechanical properties of each core can reduce experimental variation. Alternatively, incoming cores can be tested at standard test conditions against perforators with known performance history in order to qualify targets by batch or lot.

4.5 4.5.1

TESTING REQUIREMENTS General Requirements

Figure 13 illustrates a typical testing equipment schematic. The testing equipment required for a Section 4 experiment shall generally consist of the following: a. target confinement system, b. simulated wellbore system, c. surge simulation system, d. simulated perforating gun system, e. pressure control and measurement system, f. flow control and measurement system, and g. data acquisition system.

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Inlet flow distributor Screen

Flexible jacket

Screen Outlet flow collector

Not To Scale

Figure 11—Typical Axial-Flow Permeability Equipment


29


Flow distributor

Flexible jacket

´ L

Flexible, permeable packing

Not To Scale

Figure 12—Typical Diametral Flow Permeability Equipment

30

4.5.2


Target Confinement System

The target confinement system is composed of the target assembly and a confining pressure vessel that is designed to apply uniform hydrostatic stress to the target. The inside diameter of this vessel shall be of sufficient size to not cause test artifacts. Application of load shall be controlled and be of a rate that will not cause sample problems due to loading. The composition of the jacket shall be an elastomer material, capable of adequate deformation to seal on the core and endcaps as required. Consideration should be given to the temperature and fluids that the jacket will be exposed to. System pressurization fluid is at the discretion of the testing company. Using fluids incompatible with the test process can cause target contamination and invalidate the test results.

Wellbore pressure

Overburden pressure

Gas charged accumulator

Target Pore pressure

Gas charged accumulator

Simulated wellbore

Perforating gun

Simulated overburden pressure vessel

Figure 13—Schematic of Typical Testing Equipment 4.5.3

Simulated Wellbore System

The simulated wellbore system consists of the wellbore pressure vessel that when connected to the target confinement system allows for the creation of three distinct pressure regimes (confining, wellbore, and pore). The design of the vessel needs to consider the dynamic shock events that will occur inside, and appropriate factors of safety must be used to account for these conditions. The design also needs to consider the wide range of fluids that this vessel could be exposed to. Proper material selection is critical to ensure safety when designing and using a vessel that will be subject to high stress and pressure, dynamic shock, corrosives, and caustics. Improper material selection can be dangerous. The wellbore volume needs to be of sufficient volume to contain the simulated perforator gun but must be controlled as much as possible to match appropriate perforation conditions. The effect of wellbore volume and configuration is not well defined, but one should expect that changes in volume and geometry will significantly affect the response of the system to dynamic pressure events. Debris or test fixture movement during the perforation event may obstruct the perforation tunnel entrance. Depending on the parameters of the test, this may be significant or a source of experimental error. Other considerations include explosive loading procedures, proper data collection, and flow paths during and after the perforation event.


4.5.4


31

Surge Simulation System

The surge simulation system shall be used to supply the “surge flow” into and/or out of the test target during the perforation event. This surge flow is meant to mimic the response of reservoir and the wellbore to the creation of the perforation and casing entrance hole. This surge flow is most typically done with accumulators. In the baseline case, the goal shall be to provide a constant pressure boundary condition at the reservoir side of the target. To this end there should be minimal restriction to flow in the plumbing between the pore side accumulators and the core. Increasing the volume of accumulators on the reservoir side will also minimize the loss of reservoir pressure after perforating. The level of gas precharge on the reservoir side accumulators will affect the amount of fluid available for the surge flow and the final pressure of the pore fluid after perforating. The amount of accumulation volume and design of this system shall be left to the testing company as part of the overall design of the facility and experiment. This system can be used to tailor the amount of perforation clean up and to compensate for geometry driven dynamic system events.

4.5.5

Simulated Perforating Gun System

The simulated perforating gun system shall consist of a sealed chamber containing the charge, detonating cord (if used), and detonator. It must be designed to mimic the gun that matches the charge being used in the experiment. It must have a realistic thickness and design as a field gun in the area where the charge would penetrate the gun body, including the scallop. It must match the in-gun standoff that the charge would have in a field gun used in a relevant application. It should be positioned in the wellbore in such a way to hold and maintain the water clearance between the gun and the simulated casing endcap to match that of the field gun in the wellbore. The internal volume of the gun module is a variable that can be adjusted to affect the dynamic surges during the perforating event. Two types of gun designs mimicking carrier guns are most common. One utilizes shooting the charge in the true geometry (out the side of the carrier). The second utilizes a design shooting the charge through a flat plate that mimics the wall thickness of the gun and scallop. Each has advantages and disadvantages. The design is left to the testing company to decide which design is possible in their particular system and which one provides the best flexibility and reliability. Use of exploding bridge wire (EBW) detonators is recommended for safety reasons. Be sure to follow all recommendations and requirements of the EBW detonator supplier that is used, as requirements do vary from manufacturer to manufacturer. In consideration of the charge selection for use in testing of this type, a. every effort should be made to reduce charge performance variation in this type of testing; b. verification of performance and repeatability is recommended prior to initiation of any test program; c. charges to be used should be thoroughly inspected and examined prior to use to eliminate any that have deteriorated or appear to be suspect; d. where possible, all charges for a given test program should come from the same box of charges and/or same date shift code; e. minimum run lots are not specified for these tests as it is not useful or meaningful; and f. origin and description of charges used should be reported.

4.5.6

Pressure Control and Measurement System

The pressure control and measurement system shall consist of the pumps, transducers, and valves used to supply, maintain, and control the high pressure confining pressure, reservoir pressure, and wellbore pressure needed for these experiments. Adequate pressure relief capacity must be supplied to protect the test vessels from over-pressure conditions due to equipment malfunction or operator error. The design and specification of this system is left up to the testing company. The expected minimum accuracies of the pressure measurement devices are discussed in 4.8. Pressure measurement and control are extremely important. Variations in pressure control or errors in the differential pressure measurement will introduce major amounts of error and variation into the test results.

4.5.7

Flow Control and Measurement System

The flow control and measurement system shall consist of the flow pumps, controllers, flow meters, and valves used to supply, maintain, and control the fluids being flowed through the test target in either the production or injection directions. Test fluids can

32


include oil, water, or gas in single phase or in various combinations. The required accuracies for the flow measurement equipment are discussed in 4.8. The design and specification is left up to the testing company. a. Flow measurement and rate control are extremely important. An improperly designed system will introduce major amounts of error and variation into the test results. Note that it is recommended for simplicity (but not required) to control the rate and measure the differential pressure for a liquid flow and to control the differential pressure and measure the rate for a gas flow. b. Fluid filtration is critical. Improper or inadequate filtration will result in core plugging, which will add error to the pressure drop measurements, which will affect the final results. This should be evaluated for any system as noted in 4.8.

4.5.8

Data Acquisition System

The data acquisition system shall consist of the required equipment to accurately record all data from a Section 4 test with the accuracy required for each testing type. The equipment configuration shall be at the discretion of the testing company with the exception of the following. a. Analog to digital conversion can be a source of significant error. The use of higher resolution A-D conversion can help to increase accuracy. b. The system shall be capable of collecting “fast data” at the time of the perforator detonation. At a minimum these measurements should be collected from the wellbore pressure; however, gun peak pressure and pore pressure may also be useful to understand system response. In general, rates of 5000 samples per second are the minimum acceptable. c. Care should be taken to reduce noise from detonator initiation and other electrical interference and to ensure proper placement of the transducer to avoid error due to shock reflections.

4.6

TEST TARGET SETUP

4.6.1 Perforating tests shall be performed using cylindrical cores. The core shall be provided with a faceplate on the end to be perforated that simulates the well casing and cement sheath between the casing and the borehole wall. There shall be a flexible jacket that transmits simulated overburden stress to the sample. There shall be a faceplate on the unperforated end to allow for application of pore pressure to the appropriate boundaries of the sample. For axial flow only, constant pressure shall be applied to the unperforated end of the core only. For radial flow, pore pres sure can be applied in two different methods. The first method shall be to apply constant pressure to the cylindrical sides of the core via a gap between the jacket ID and core OD that is filled with a permeable media AND to the unperforated end. The second method shall be to apply constant pressure to just the cylindrical sides of the sample using the same method. For most types of rock either can be used. Typical arrangements are shown in Figure 14 and Figure 15. The specific target geometry to be used shall be at the discretion of the testing company, except for the following. a. Target diameter should generally not be less than 4 in. b. The entrance hole shall be positioned in the center of the faceplate, and after shooting, the tip of the perforation tunnel shall not be further than one-fourth of the target diameter from the centerline axis of the target. c. After shooting, there shall be a minimum distance equal to one target diameter between the tip of the perforation tunnel and the unperforated end of the target. d. In general, only samples with bedding planes oriented parallel to the core axis should be used in axial-flow geometry tests. This is particularly important when K v/ K h is low, in which case experimental variation can be significantly increased, but less important when K v/ K h approaches 1. e. Simulated overburden stresses shall be applied uniformly to all portions of the sample. Axial and radial stresses may be different, if desired, and if the test system allow for this. f. The target geometry and setup used shall be tested to provide assurance that no flow is able to bypass the perforation.

4.6.2 For radial flow geometries, the target is configured with a constant pressure boundary condition on the core OD surfaces, an optional content pressure boundary condition on unperforated end of the core, and a no flow boundary condition on the perforated end of the core. The annular gap between the sample jacket and core OD shall be filled with a stress transmission media with permeability at least 100 times greater than the expected permeability of the test core. Refer to Figure 14 for further details and descriptions. In most cases, a high strength proppant can provide this capability. This will address potential test artifacts concerning flow restrictions, media crushing, and poor stress transmission. The face of the perforated end of the core must be sealed with a gasket to ensure that all flow exiting the core comes by way of the perforation. There are several ways to accomplish this, and it is left to the discretion of the testing company to select a method and then do the required testing to assure that there is no leakage. The endcap on the unperforated end of the core should normally be configured to include a flow


Faceplate Neat cement

33


Faceplate Neat cement

Flexible jacket

Optional gasket

Flexible jacket

Flexible, permeable packing

Optional gasket Optional baffle plate Flow distributor Not To Scale

Figure 14—Typical Radial-Flow Geometry

Flow distributor Not To Scale

Figure 15—Typical Axial-Flow Geometry

34


distributor to distribute flow across the entire face of the core and/or to direct fluid to the porous media surrounding the OD of the core.

4.6.3 For axial flow geometries, the target is configured with a constant pressure boundary condition on the unperforated end of the core and a no flow boundary condition on the core OD and perforated end of the core. This is best accomplished with a flexible jacket on the core OD, a flow distributor on the unperforated end, and a sealing gasket on the perforated end. Refer to Figure 15 for additional description and details. 4.6.4

For all testing configurations it is important to minimize all sources of bypass flow around the perforation tunnel, such as:

a. flow between the core OD and flexible jacket—use a thick deformable material for the sleeve; b. flow between the cement in the endcap on perforated end and the core—use a gasket of some sort to stop flow path; c. flow between the steel endcap and cement in the endcap—use a cement or grout mixture that does not shrink or that expands while curing; and d. any bypass leaks in the flow system—ensure that all flow has to go into and through the test target and exit through the perforation tunnel.

4.6.5 The flow distributor to be used is best constructed with a series of concentric circular grooves and radial connecting grooves, such that a balance between axial stress transmission and the constant pressure boundary condition is reached. a. Too small an area in the grooves and rings will cause excessive pressure drop. b. Too large an area in the grooves and rings will cause an excessively high contact stress between the core and the end plate. This could cause localized failure, releasing fines and affecting the results. c. Screens may be used between the end of the core and the flow distributor to try and better spread the fluid flow and loading out across the end of the target. d. The screens are also needed for radial flow geometries to keep the proppant from being washed out back into the inlet flow lines. e. Materials of construction should consider what pore fluids are envisioned for use.

4.6.6 The endcap used on the perforated end of the core should be flat and flush with both the test fixture and core. Neat oilfield cement or nonshrink grout is recommended. Avoid gaps due to shrinkage, as these will provides sources of error in the results. 4.7

GENERAL PERFORATION TESTING PROCEDURE

4.7.1 The following perforation test procedure is provided as a basic guideline for testing companies. The actual specific procedures to be followed for a perforation and flow test shall be left to the discretion of the testing company to define and follow. The testing company shall be responsible to technically justify their specific procedures. 4.7.2 Increase confining pressure to appropriate level. Avoid applying stress higher than the planned test condition to the core. Once appropriate confining pressure is reached, increase confining pressure, pore pressure, and wellbore pressure either simultaneously or sequentially until desired testing conditions are reached. A bypass line between pore pressure and wellbore pressure is useful during this operation in order to keep pressures equal until ready for final conditions. Other test conditions, such as specialized wellbore fluid, may prohibit this or require alternative configurations. 4.7.3 Allow sample to equalize. Lower permeability targets may require additional time for induced pore pressure to bleed from the target. 4.7.4

Initiate or arm trigger for high speed data collection systems if present.

4.7.5

Arm and detonate perforator.

4.7.6

Allow well pressure and pore pressure to equalize.

4.7.7 If desired, the equalized wellbore/pore pressures may be slowly reduced to a lower or ambient pressure while keeping effective stress constant. Fluctuations in effective stress or differential pressure between the pore and wellbore may invalidate the test. Backpressure can be effective in reducing test time. 4.7.8

Isolate surge system from flow lines.



35

4.7.9 Flow shall be initiated through the sample by applying desired draw down or flow rate. This value will depend on the flow geometry chosen and effective permeability of the perforated sample but should not exceed the clay or fines mobilization threshold rate of the target. 4.7.10 Flow should be continued at initial rate until steady state is reached, i.e. flow rate and pressure drop are constant and temperature measurements have equalized. 4.7.11 Flow at same rates or pressure draw down as when the core was characterized. These may be different depending upon the discretion of the testing company. Do not exceed the maximum flow rate of the initial characterization, or the pressure differential by twice original maximum. 4.8

SYSTEMS CALIBRATION AND TEST REQUIREMENTS

4.8.1 At a minimum, all transducers, gauges, controls, and instrumentation shall be calibrated against a suitable reference standard at intervals not exceeding one year, per ISO 9001 standards and procedures (current edition). It is best to calibrate the transducers in place, utilizing all of the cables, amplifiers and DAC in the calibration. Not doing so could introduce error and variation into the tests system and subsequent results. 4.8.2

Systems verification tests should be:

a. conducted prior to the commissioning of any new test system; b. conducted after any major modifications to any existing system; and c. conducted every two years, even if there are no major changes.

4.8.3 Verification tests to be conducted are to be designed by the testing company but shall include, but not be limited to, the following as a minimum. a. System Flow Rate —Be able to measure liquid and/or gas flow rates with an accuracy of ±1 % of full scale. Liquid flow rates may be between 10 cc/min and 1000 cc/min for medium and low permeability targets and at rates from 1001 cc/min to 10,000 cc/min for higher permeability targets. b. System Pressure Drop —For pressure drops between 1 psi and 50 psi, be able to measure within ±0.50 psi. For pressure drops between 51 psi and 250 psi, be able to measure within 1 psi. For pressure drops between 250 psi and 500 psi, be able to measure within 2 psi. For pressures greater than 501 psi, be able to measure within 0.5 % of the measured value. c. Viscosity/Temperature/Liquid Density —Temperature measurements should be within ±2 °F of the measured value. Liquid density should be accurate within 1 % of the measured value. Fluid viscosity must be measured using suitable equipment and be available in tabular form.

4.8.4 Recommended system calibration tests shall be conducted by the testing company following their own procedures and shall include the following. a. Conduct a test to determine the system pressure loss, excluding the rock core. The test should determine the pressure loss between any pressure measurement location and the rock core face (inlet or outlet end). For this test, a test fixture with infinite permeability should replace the rock core. The pressure drop measurements should be done across the entire range of flow rates that are capable for any given laboratory test system. b. Conduct a test to verify that there is no flow bypassing the perforation tunnel in the test setup. The designs of these tests are left up to the testing company and would include verification of the following: 1. no flow leakage between the core OD and the flexible jacket in axial flow geometry tests., i. e. all flow must go through the core, not around the core; 2. no flow leakage between the core exit face and the core OD for radial flow geometry, i.e. all flow must go through the core and not around the core; 3. no flow leakage across the outlet face of the core and the perforation tunnel and hole through the endcap, i.e. all flow must exit the core through the perforation tunnel; 4. no flow leakage around the outside of the cement plug in the perforated endcap and the hole through the steel plate, i.e. all flow out of the perforation tunnel must go through the cement hole and simulated casing exit hole. c. Conduct a test to verify that the fluid filtration system is adequate by performing a flow test through a nonperforated core and measuring the pressure drop to constant flow. Any increases in pressure differential shall indicate that pore throat plugging is occurring.

36


4.9

DATA RECORDING

For each sample tested, the following raw data shall be recorded as appropriate. a. A record of the test geometry and flow boundary conditions. b. Target properties: 1. type; 2. diameter, length, and orientation; 3. preparation conditions; 4. permeability, porosity, and density; 5. UCS; and 6. casing and cement configuration and materials. c. Test conditions during both flowing and shooting. d. Perforation geometry data should be collected after all flow testing, including the following. 1. Casing entrance hole diameter, minimum through diameter, and cement exit hole diameter in two orthogonal directions. 2. Probe penetration—depth that 24 in. long 1/8 in. rounded tip probe can be placed vertically into target with no external force. 3. Clear tunnel penetration—length from target face to first competent structures within the perforation. In general this can be determined by a combination of probing with moderate force, gentle washing of loose material, and visual inspection. 4. Total core penetration—length from target face to furthest evidence of penetration in the target. This can be determined visually from a split core or from CT or other noninvasive scanning methods. 5. Perforation diameter profile—the diameter of the perforation shall be recorded at 0.5 in. or 1.0 in. intervals along the length of the perforation. This may be done by recording the coordinates of the perforation walls in tabular form, by sketching the perforation on an appropriate grid, or by attaching a photograph or scan of the perforation, again with an appropriate scale grid. The average perforation diameter shall be recorded to the nearest 0.1 in. 6. Maximum tunnel geometry—the maximum potential diameter and length of the open perforation tunnel. This geometry is produced by scrubbing the perforation tunnel with a brass cylindrical wire brush to remove all weakened rock. Scrubbing shall be “calibrated” against undamaged rock so that it does not remove undamaged rock around the perforation. Diameter of resulting tunnel should be measured and recorded at 0.5 in. or 1.0 in. intervals along the length of the perforation. e. A tabular record of all collected and calculated flow data, including flow rate, inlet pressure, outlet pressure, differential pressure, inlet and outlet temperatures, viscosity, fluid density, and permeability, or other measure of flow performance. f. A high speed plot of the pressures during the perforation event.

4.10 4.10.1

LIQUID FLOW DATA REDUCTION General

Flow data may be presented in either of two formats: CFE or PR. Convergent flow production ratio (CFPR) may be used as an alternative to production ratio in strongly heterogeneous targets. In general, radial flow geometry is better suited to a CFE or a modified CFPR analysis, and axial flow geometry is better suited to analysis with PR and CFPR. Neither CFE, PR, nor CFPR completely describe the flow performance of a given perforation. These calculated values should only be considered in the context of other measurements and the test program parameters. The choice of the data reduction analysis shall depend upon the goals of the testing program and shall be left to the discretion of the testing company. Productivity index (PI) is defined as the ratio of flow rate, corrected by viscosity of the fluid, to pressure drop and is determined from the slope of a linear curve fit though a corrected flow versus pressure drop data plot, as shown below in Figure 16. PI is only valid within the context of a given set of test conditions and is dependent upon such things as boundary conditions, target properties, and fluid properties. The corrected flow term Q* is calculated according to Equation 4-2 and has units of cm 3/min:

*

µ µ ref

Q = Q -------

(4-2)


37


250

200

          

   

Q

Experimental Error

PI

150

Q  P - 2.2

100

50

0 0

20

40

60

80

100

120

  

Figure 16—Productivity Index Data Reduction Graph where Q = measured flow rate (cm3/min;) µ = fluid viscosity (cP); µref = fluid viscosity at 75 °F and 1 atm. (cP). Alternately, PI may be calculated at a single point according to Equation 4-3: *

Q PI = ------- ∆ P

(4-3)

where Q* =

corrected flow term (cm3/min);

∆ P = differential pressure corrected for flow system pressure drop (psi.) PI may be used to calculate perforation performance, and permeability for various boundary conditions. Axial flow permeability, K a, in mD, shall be calculated according to Equation 4-4: PI µ ref L K a = 30.69 ---------------2 R where PI = productivity index (cm3/psi min); µref =

fluid viscosity at 75 °F and 1 atm. (cP);

L

= core length (in.);

R =

core radius (in.).

(4-4)

38


Diametral flow permeability, K d, in mD, shall be calculated according to Equation 4-5: PI µ ref K d = 96.43 ------------ FL ′

(4-5)

where PI = productivity index (cm3/psi min); µref =

fluid viscosity at 75 °F and 1 atm. (cP);

L´ = length of 90° arc flow inlet and outlet area (in.); F =

cross diameter flow correction factor.

The cross diameter flow correction factor, F , corrects the apparent diametral permeability for errors due to flow beyond the test region due to axial fluid movement. This correction is especially important for targets with a high ratio of K a to K d but can represent a 10 % reduction in apparent permeability for even isotropic targets [5]. This correction is dependent upon the geometry of the cross diameter flow fixture. For 7 in. diameter by 18 in. long cores with 12 in. long 90° inlet and outlet flow distributors, F can be calculated according to Equation 4-6: 0.7162log K d F = 1.232 – 0.2371 tanh ------------------------------ + 0.612 K a

(4-6)

For other diametral flow/target configurations, similar correlations for F would need to be developed.

4.10.2

Core Flow Efficiency

CFE shall be defined as the ratio, observed perforation productivity index (PI perf ) to open tunnel productivity index (PI OT), according to Equation 4-7: PI perf CFE = ----------PI OT

(4-7)

CFE analysis is dependent upon the geometry used to estimate PI OT, as well as the cross diameter flow measurement. Both of these can be sources for experimental variability. CFE analysis is a measure of the flow performance of the entire perforation, emphasizing flow through the side walls of the perforation. In addition, since CFE is generally used in conjunction with radial flow perforation geometry, it is then a measure of the flow performance of perforations produced by radial flow testing, which generally differ from perforations produced by axial flow testing. The CFE calculation is generally used to estimate the permeability map around the perforation tunnel, most simplistically represented as a constant thickness “damaged zone” of reduced, constant permeability surrounding the entire perforation. This estimate is an input into many perforation and well inflow models. This simplification may be significant and is an area of active investigation. Suitable means shall be used to calculate PI OT based on measured maximum tunnel geometry, as specified in 4.9, axial permeability, K a, diametral permeability, K d, and applied pressure boundary conditions. The best way to calculate PI OT is with a numerical computational flow dynamics (CFD) model. The specific numerical means of calculating the PI open tunnel shall be at the discretion of the testing company. Alternately, for a radial flow target with bedding planes perpendicular to the long axis of the core, the following one dimensional analytical solution may be used:

– 2 1 K 1 D K 2 rR PI OT = 6.516 × 10 ------- ---------- + -----------µ ref ln R R – r ---------r

(4-8)


39


where PIOT = productivity index of the maximum tunnel geometry (cm3/psi min); µref = fluid viscosity at 75 °F and 1 atm. (cP); D = perforation depth (in.); R = core radius (in.); r = maximum tunnel radius (in.); K 1 = K d; K 2 =

3

2

K a K d .

This analytical solution typically overestimates the PI compared to the results of CFD simulations.

4.10.3

Production Ratio

Production ratio shall be defined as the ratio of the PI perf to the pre-shot PI of the target, calculated according to Equation 4-9: PI perf PR = ----------PI

(4-9)

This analysis may be used for multiple pre-shot and post-shot geometry combinations, including axial flow and radial flow, so long as boundary conditions at the unperforated boundary are the same both before and after the perforation event.

4.10.4

Convergent Flow Production Ratio

CFPR shall be defined as the ratio of the PI perf to the pre-shot PI of the target with restricted outlet, calculated according to Equation 4-10: PI perf CFPR = ----------PI

(4-10)

This analysis may be used for multiple pre-shot and post-shot geometry combinations, including axial flow and radial flow, so long as boundary conditions at the unperforated boundary are the same both before and after the perforation event.

4.11 4.11.1

GAS FLOW TESTING General

Gas flow testing requires additional treatment compared to liquid flow testing. In this section, basic principles, testing procedures, and treatment of data are outlined. This is not, and is not meant to be, an exhaustive compilation of all possible tests. Tests can be run with dry core/dry gas, cores at irreducible brine saturation (Swi)/humidified gas, or cores at irreducible oil saturation (Sor)/ dry gas. Data may be reduced in terms of either CFE or PR. Gas production or injection flow, even at relatively low rates, differs significantly from liquid flow due to compressibility effects and nonlinear friction. As a result, a simple single-parameter Darcy law is not adequate to fully characterize the pressure drop. A convenient method is presented for reducing the experimental data such that the permeability and Forchheimer inertial drag coefficient (cf ) can be determined directly. The choice of the data reduction analysis will depend upon the goals of the testing program, and shall be left to the discretion of the testing company. Nitrogen, either humidified or dry, is recommended for the gas phase. Properties such as viscosity and density may be determined from http://webbook.nist.gov for either isobaric or isothermal conditions. In many cases it is a small error to neglect the pressure drop and temperature change across the core during testing and use a constant viscosity and density for the data reduction operation.

40


16

) s p 14 ( e r u s 12 s e r P l 10 a i t n e r e 8 f f i D x 6 e r u s s e 4 r P e g 2 a r e v A 0

x 10-4

2 i

y =

6.07e + 012

x x2 +

1.135e + 009

x x -

317.9

Data 1 Quadratic

0

1

2

3

4 5 Mass Flux (kg/s-in. 2)

6

7

8

9 -5

x 10

Figure 17—Example Gas Flow Curve Fit to Determine a1 and a2 4.11.2

Target Preparation

Targets should be prepared as recommended in 4.2 and 4.3. For targets initially brine saturated, humidified gas should be used during the Swi process and testing in order to maintain consistent saturation level. A pressure drop between 10 % and 25 % higher than desired maximum test pressure drop should be used while desaturating the target. Targets should be weighed at every opportunity to verify saturation state and stored for only short periods of time if at all prior to perforation. Humidified gas may be produced by flowing the gas stream through a freshwater chamber located in line immediately adjacent to the target inlet. Increasing evaporation surface area may help to reduce experimental error.

4.11.3

Target Characterization

Targets should be characterized with axial flow and diametral flow in two orthogonal directions. Convergent flow testing should not be used for targets with multiple phase saturation due to potential for local changes in Swi. The linear and quadratic coefficients, a1 and a2 respectively, are obtained by graphing the pressure and mass flux data as demonstrated in Figure 17 and calculating a quadratic equation curve fit in the form of y = a2 x2 + a1 x + c. This provides for a direct means of evaluating k and cf for convergent flow in Equation 4-11: 6 µ L k = 5.79 ×10 ⋅ -------a1β

– 6 a 2 k β c f = 3.55 ×10 ⋅ -------------- L

(4-11)


41


where k = axial permeability (mD); cf = Forchheimer coefficient; µ = average fluid viscosity (cP) at P ; P = average of inlet and outlet pressures (psi); L = core length (in.);

β = ideal gas isothermal compressibility (gm/cc/psi). The case of compressible flow in the diametral direction yields similar results to the axial flow case in Equation 4-12. The flow length is now the quadrant chord length of the core cross-sectional area. The flow area is the product of the chord length and the flowed length. Again, a1 is the linear coefficient and a 2 is the quadratic coefficient. 6 µ 2 D core k h = 5.79 ×10 ⋅ --------------------2a 1 β

(4-12)

– 6 2a 2 k β c f = 3.55 ×10 ⋅ ----------------- L

where k h = diametral permeability (mD); µ = average fluid viscosity (cP); Dcore = core diameter (in.);

β = ideal gas isothermal compressibility (gm/cc/psi). 4.11.4

Production Ratio

Gas flow axial production ratio shall be defined as the ratio of the PI perf to the pre-shot PI of the target, calculated according to Equation 4-13: PI perf PR = ----------PI

4.11.5

(4-13)

Core Flow Efficiency

CFE shall be defined as the ratio, productivity index (PIactual) to ideal productivity index (PIideal), according to Equation 4-14: R core c f Qm µ  ------------------------- ln  ------------ + -------- ---------------------------2  2k h βπ DoP  Rtunnel  k h β ( 2 π L ) Leff 

PIactual 6 CFE ( Q m ) = -------------- = 5.79 ×10 ⋅ --------------------------------------------------------------------------------------------------PI ideal a 1,actual + a 2,actualQ m

(4-14)

42


where Qm = mass flow rate (kg/s); DoP = depth of penetration (in.); Rcore = core radius (in.); Rtunnel = perforation tunnel radius (in.); R core Rtunnel Leff = effective flow length = ---------------------------- (in.). R core – Rtunnel Note: Evaluation of a1 and a2 for radial flow requires fitting a quadratic curve to a plot of the average pressure times the pressure difference vs. the mass flow rate in kg/s, not the mass flux (kg/in. 2-s)., as shown in Figure 18.

12

x 10-4

) s p ( e r 10 u s s e r P 8 l a i t n e r e 6 f f i D

2 i

y =

1.768e + 008

x x2 +

3.66e + 006

x x -

240.9

x

e r u s s e r P e g a r e v A

4 Data 1 Quadratic

2

0

0

0.002

0.004

0.006

0.008 0.01 Mass Flowrate (kg/s)

0.012

0.014

0.016

Figure 18—Post-Shot Radial Flow for a Gas Saturated Core 4.12 4.12.1

STANDARD TEST CONDITIONS General

The following additional specifications are provided so that data can be collected and compared under common conditions. All specifications and recommendations above apply. Data collected under these conditions do not represent, and may not be translatable to, any particular downhole conditions. Permeability damage caused by the perforator may be different in actual reservoir rock and under actual downhole pressures. Post-shot clean up may differ from standard test results depending on actual reservoir rock properties, the underbalance used, dynamic wellbore storage effects, dynamic pressures surges introduced by the gun system, production drawdown, fluid composition and viscosity, perforating phasing and shot density, and other factors. For best site-specific results, the general test specifications above allow simulation of each of these factors. The standard test is intended as a means of qualifying laboratory facilities as capable to produce industry consistent results. As the technology of perforation testing evolves, additional critical variables may be identified that are not accounted for in this test. This test is not meant to preclude any laboratory from performing additional measurements or a modified simulation in order to best accomplish the goals of a given internal or customer funded program. Specific recommendations for test configuration for specific programs are left to the discretion of the testing company. In the best case, core shall be pulled from a bank of standard rock, and charges shall be supplied from a bank of standard charges. Results should be published on a standard datasheet. The compilation of results from all laboratories performing this test should be made public to the API membership.


4.12.2


43

Rock Samples

Test samples shall be of Berea sandstone or equivalent, meeting the specifications listed in 4.2. Ideally, a specific set of blocks will be identified. For this qualification test, targets shall be cut with bedding planes parallel to the long axis. Target diameter will be as specified by the testing company.

4.12.3

Test Charges

Ideally, two specific, commercially available lots of test charges shall be identified, nominally 15g HMX and 25g HMX. For the qualification test, the testing company may request any size charge for any size target.

4.12.4

Pore Pressure Boundaries

For the qualification test, the core shall be tested in axial flow geometry. Pore pressure shall be applied to the end of the core opposite the perforation only. All previously discussed recommendations regarding target construction shall apply.

4.12.5

Test Fluid

For the qualification test, the test fluid shall be single-phase OMS. The core shall be saturated per single-phase saturation recommendations in 4.3. The testing company shall provide a viscosity/temperature/pressure curve which includes the range of temperatures experienced in the test for the fluid used with the test result submission.

4.12.6

Pre-Shot Target Characterization

For the qualification test, the target shall be characterized and data reported per 4.4, including and limited to measurement of axial permeability, porosity, density, dimensions, and optionally mechanical properties. Axial permeability shall be measured at flow rates of 60 cc/min, 90 cc/min, 120 cc/min, and 180 cc/min.

4.12.7

Shooting Conditions

The casing plate shall be 0.5 in. thick 4140 HT Steel, Rc 28-32. Cement shall be 0.75 in. thick neat Portland cement. A gasket as previously described shall be used between the cement and the core face. The water clearance between the gun and casing plate (gun clearance plus scallop depth, if present) shall be 0.75 in. Internal charge standoff shall be as specified by the manufacturer of the charges used in the test. Charge manufacturer shall provide estimate of internal gun volume, but this may be adjusted at the testing company as required. A pressure–time perforating profile for each charge size is provided. The testing company shall modify appropriate variables as required in order to best match the dynamic events of the provided profile. Applied static pressures when the gun is fired shall be as follows: Confining Pressure:

6500 psi

Pore Pressure:

3500 psi

Wellbore Pressure:

3000 psi

This provides an effective rock stress of 3000 psi and 500 psi underbalance.

4.12.8

Post-Shot Flow Performance Evaluation

The perforated core shall be evaluated in axial flow at, but not limited to flow rates of 60 cc/min, 90 cc/min, 120 cc/min, and 180 cc/min. Measurements shall be conducted in accordance with recommendations in 4.5, 4.6, and 4.7. Data recording shall be conducted in accordance with recommendations in 4.9. Data reduction shall be conducted in accordance with recommendations in 4.10 for axial flow and production ratio.

4.12.9

Standard Test Datasheet

A standard datasheet is provided in Figure 19 for use in reporting the results of the standard test.

44


SECTION 4 STANDARD TEST DATA RECORDING SHEET

Test: ID No:

Date:

TARGET PROPERTIES

CORE PREP CONDITIONS

Rock: Diameter: Length: Bedding: Dry Wt: Sat Wt: Sat Fluid: Porosity: Density: UCS:

Confining: Pore: Wellbore: Fluid Flowed: Temperature:

Wellbore: Wellbore Fluid: Wellbore Temp: POST-SHOT CONDITIONS

Confining: Pore: Pore Fluid:

CASING AND CEMENT

Size & Grade: Casing Wall: Cement Type: Cement t:

2"

Post Axial Pl: Post Injection Pl: Post Radial Pl: PERFORATING RESULTS

Gun Entr. Hole: Casing Entr. Hole: Casing Exit Hole: Cement Hole: Probe Depth: Clear Tunnel Depth: Total Pene. Depth:

 

Wellbore: Temp:

PERFORATION TUNNEL DIMENSIONS

1"

POST-SHOT FLOW DATA

 

Charge: Exp. Mass DSC: Gun Syst: Gun Wall T: In-Gun Cir:

0"

PRE-SHOT FLOW DATA

Pre-Shot Axial Pl: Pre-Shot Inj. Pl: Diametral 1 Pl: Diametral 2 Pl: Avg. Diametral Pl: Convergent Flow Pl:

SHOOTING CONDITIONS

Flow Geometry: Confining: Pore: Pore Fluid:

SHAPED CHARGE

DEPTH

Engineer: Technician:

AS-FOUND

SCRUBBED

NOTES AND COMMENTS

DATA REDUCTION & ANAL YSIS

Axial PR: Injection PR: Radial PR: Convergent Flow PR: Theoretical PI (CFD): CFE: Kc/K: Single Perf. Skin:

3" 4" 5" 6"

Avg. As-Found Tunnel Dia: Avg. Scrubbed Tunnel Dia: Estimated Crushed Zone t:

7" 8" 9" 10"

Engineer Signature: Date:

11" 12" 13"

Witness Signature: Date:

14" 15" 16" 17" 18"

Figure 19—Section IV Standard Test Data Recording Sheet


5


45

Debris Collection Procedure for Perforating Guns

5.1

HOLLOW CARRIER PERFORATING GUNS

Because of the complexity and variability of well conditions it is thought to be impossible to determine with any degree of accuracy, the amount of perforating debris that will be left in a well bore by conducting a surface test. Since a down hole test is neither practical nor affordable it was necessary to design a surface test whereby potential gun debris could be quantified specifically for the purpose of comparing competing systems. This procedure does not address casing scale or debris from any other source but the perforating gun. Debris is defined as all solid materials that are blown out of the exit holes in the gun at the time of detonation, or fall out of the exit holes during the trip out of the well. This test was designed to quantify the debris that comes out of a perforating gun upon detonation, and also identify and quantify any debris remaining in the gun that is small enough to potentially come out of the gun on the trip out of the well. It is designed for comparative purposes only and should not be used to determine the amount of debris that will be left in any given well bore. The following requirements must be met to properly conduct this test: 1. Standard field equipment available to any customer must be used. 2. The gun assembly must have a minimum of 2.5 continuous linear feet of perforations. 3. The entire gun must be fully loaded to the maximum shot density. 4. With exception of the bottom sub/plug, which must be solid or blanked off, the gun assembly shall consist of standard field equipment and other parts as specified in 1.3. 5. The test must be conducted with the gun inside a water filled casing, and positioned the same as a standard API Section 1 test. 6. This test can be done concurrently with a standard API Section 1 test if the gun has the required 2.5 linear feet of perforated zone, and is fully loaded. Otherwise the test must be conducted separately using a water filled casing backed with water or concrete. 7. The casing size, weight, and grade, must meet the requirements of Table 2, and must be the same size that would normally be used in a Section 1 test for that system. 8. The charges used must be standard and come from a single production lot of not less than 300 each for HMX and higher temperature charges, and not less than 1,000 each for lower temperature charges, as defined in 1.4. 9. The gun must be restrained to stay inside the casing and in a vertical position after the detonation. Phase I of the procedures below addresses the debris that is blown out of the gun at the time of detonation. Phase II addresses debris that is small enough to come out of the exit holes but remains in the gun after detonation. Use the guidelines below to measure and record the test data: 1. All final weights and volumes in Phase I and II must be calculated and presented as amounts per linear feet of perforations. 2. The calculations must be based upon a fully loaded interval, and not include lengths for tandems or other non perforated lengths. Example: A 4-foot long gun may only contain 2.5 feet of perforations. 3. All measuring equipment must be properly calibrated.

5.2

PHASE I

The objective of this phase is to determine the amount of solid debris loss at the time of detonation. This is done by measuring the amount of weight loss achieved upon detonation from solid materials that are not consumed in the detonation process. The following steps comprise Phase I.

5.2.1

Gross Pre-Test Weight of Loaded Gun Assembly

Weigh the loaded gun assembly including all explosives and record this weight in kilograms to the nearest 10 grams.

5.2.2

Total Weight of all Solid Materials Consumed in the Detonation

Calculate the total weight of all materials that will be consumed during the detonation. This should include the following:

46


1. Total calculated weight of all explosives in the charges based on design data 2. Total actual weight of all detonating cord including the sheath 3. Total calculated weight of all charge liners based on design data or actual weight 4. Total actual weight of any other solid materials inside the gun that are consumed upon detonation. 5. If applicable See 5.4 to determine amount of charge case debris consumed in the detonation Add the weights of all above items and record to the nearest one gram.

5.2.3

Net Pre-Test Weight of Loaded Gun Assembly

Subtract the total weight of all consumables from the gross pre-test weight and record in kilograms to the nearest 10 grams.

5.2.4

Shooting Procedure

Place the gun in the water filled casing in the same position it would be in for an API Section 1 test. Restrain the gun to keep it in the target and shoot it. Then carefully remove it from the target and transport it to the drying area in a manner that retains the remaining debris inside the gun.

5.2.5

Dry Weight of Expended Gun Assembly

This weight should be taken only after the expended gun assembly has gone through the drying procedure. The procedure consists of the gun being placed in an oven in a horizontal position with all the ports open, at a temperature of between 150 and 200°F for a minimum of 12 hours. The temperature used must not exceed the time and temperature rating of any potentially un-detonated explosive. Record the dry weight in kilograms to the nearest 10 grams.

5.2.6

Total Weight of Debris Lost at Time of Detonation

Subtract the dry weight of the expended gun assembly from the net pre test weight of the loaded gun assembly and record this to the nearest one gram. Note: If the number calculated is less than zero, then record as zero.

5.2.7

Weight of Debris Lost per Linear Foot of Perforations at Time of Detonation

Divide the total weight of solid debris lost at time of detonation by total number of charges, and multiply by the number of shots per foot. Record this to the nearest one gram.

5.2.8

Volume of Debris Lost Per Linear Foot of Perforations at Time of Detonation

Divide the total weight of debris lost upon detonation per linear foot of perforations by the average gram weight per cc determined in 5.3.5 of Phase II, and record to the nearest cubic centimeter.

5.3

PHASE II

The objective of this phase is to determine weight, volume, sieve size, and type of material, of all solid debris that is small enough to pass through the exit holes in the gun. It is designed to provide the weight and volume of debris in a worst case condition by rolling the gun in a horizontal position and collecting all the debris. All debris that falls out of the gun during transportation from the target, to the drying area, to the weighing scales, and to the rolling station, must be included in the total for debris that rolls out of the gun.

5.3.1

Total Weight of Debris Rolled From The Gun

Place the fully dry expended gun in a horizontal position (level within 1/4 inch) on two sets of rollers over a smooth surface. The gun must clear the surface at least three inches. Rotation speed must be constant and between 10 and 30 RPM. Roll the gun a total of 100 revolutions. Weigh all the debris retrieved and record to the nearest gram.


5.3.2


47

Weight of Debris Rolled from the Gun per Linear Foot of Perforations

Divide the total weight of debris rolled from the gun by the total number of charges, then multiply by the number of shots per foot and record this to the nearest gram.

5.3.3

Total Volume of Debris Rolled From the Gun

Use an appropriately sized graduated measuring cylinder to determine the volume of debris rolled from the gun. The graduated cylinder must meet ASTM E 1272 (Standard Specification for Laboratory Glass Graduated Cylinders) requirements for accuracy. The graduated cylinder may be tapped lightly until a constant volume is achieved. On guns with a high volume of debris add the total of all measurements and record to the nearest cubic centimeter.

5.3.4

Volume of Debris Rolled From Gun Per Linear Foot of Perforations

Divide the total volume of debris rolled from the gun by the number of charges, and multiply by the number of charges per foot. Record this volume to the nearest cubic centimeter.

5.3.5

Average Weight of Gun Debris Per cc

Divide the total gram weight of debris per linear foot rolled from the gun by the total ccs per linear foot rolled from the gun and record to the nearest 0.1 gm/cc.

5.3.6

Total Weight and Volume of Debris Lost per Linear Foot at Time of Detonation and Rolling Procedure

To make the volume calculation you have to assume that the debris blown from the gun during detonation is the same sieve size and density as the debris rolled from the gun.

5.3.7

Total Volume of Debris Lost Per Linear Foot of Perforations

Add the volume of debris per linear foot lost upon detonation to the volume of debris per linear foot rolled from the gun and record to the nearest cubic centimeter.

5.3.8

Total Weight of Debris Lost Per Linear Foot of Perforations

Add the weight of debris per linear foot lost upon detonation to the weight of debris per linear foot rolled from the gun and record to the nearest gram.

5.3.9

Debris Sieve Size Description

Determine sieve size by measuring and recording all debris rolled from the gun per ASTM E 389-03 (Standard Test Method for Particle Size or Screen Analysis at No.4 Sieve and Coarser, for Metal-Bearing Ores and Related Materials. Record the % by weight retained on each of the U.S. Sieves listed on the data sheet (see Figure 20). Also identify the type of material retained on each sieve.

5.3.10

Average Gun Exit Hole Size

Measure the exit hole sizes in the gun by measuring along the short and long elliptical axis from the outside of the gun. Use a caliper whose arms readily pass through the opening. The short axis shall be the smallest through-hole diameter measured. Record the average exit hole size to the nearest 0.01 inch.

5.3.11

Data Reporting

Use the “Gun Debris Data Sheet for Hollow Carrier Perforating Systems” as the standard reporting form. See Figure 20.

5.4

CHARGE CASE DEBRIS PROCEDURE

This procedure can be used to determine the amount of charge case material consumed during detonation. The results should only be recorded if the material for the charge case is consumable or partially consumable.



49

The charges used for this procedure must be from the same production lot as those used for the gun debris test. Charge case debris must be collected by shooting a standard charge inside a closed and sealed fixture. A steel target should be used to catch the jet.

5.4.1

Gross Pre-Test Weight of Test Assembly

Weigh the charge and test assembly. This includes the steel target and all explosives, but not the containment vessel. Record this weight to the nearest one gram.

5.4.2

Gross Pre-Test Weight of Containment Vessel and Test Assembly

Weigh the closed and sealed containment vessel including the charge test assembly and record this weight to the nearest one gram.

5.4.3

Total Weight of Solid Materials Known to be Consumed in the Detonation

Weigh and calculate the following items to the nearest gram. 1. Total calculated weight of all explosives in the charges based on design data. 2. Total actual weight of all detonating cord including the sheath. 3. Total calculated weight of all explosives in the initiators based on design data.

5.4.4

Net Pre-Test Weight of Containment Vessel and Test Assembly

Subtract the total weight of all consumables from the “Gross Pre-Test Weight of Containment Vessel and Test Assembly”. Record this weight to the nearest one gram.

5.4.5

Shooting Procedure

Restrain the charge to keep it in the fixture and shoot it.

5.4.6

Total Post-Test Weight of Unconsumed Materials

Weigh the containment vessel and test assembly after any internal pressure has been relieved, and record to the nearest 1 gram.

5.4.7

Determine the Percentage of Consumed Materials Other than Explosives

Subtract the “Total Post-Test Weight of Unconsumed Materials”, from the “Net Pre-Test Weight of Containment Vessel and Test Assembly.” If the difference is less than 5% the case material is not considered consumable. If the difference is greater than 5% go on to 5.4.8 and determine the amount of case debris consumed in the detonation.

5.4.8

Post-Test Weight of Test Assembly

Open the containment vessel and retrieve all solid debris and test assembly components. Weigh all of the test assembly components and debris, and record this to the nearest 1 gram.

5.4.9

Net Pre-Test Weight of Test Assembly

Determine this by subtracting the “Total Weight of Solid Materials Known to be Consumed in the Detonation” from the “Gross Pre-Test Weight of Test Assembly”.

5.4.10

Weight of Case Material Consumed in the Detonation

This can now be determined by subtracting the “Post-Test Weight of Test Assembly” from the “Net Pre-Test Weight of Test Assembly”. Repeat this test 3 times and record the average weight of the consumed case material to the nearest 0.1 gram. Multiply this by the number of charges in the gun debris test and record to the nearest one gram in Phase I, 5.2.2 “Total Weight of Charge Case Material Consumed in the Detonation”.

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5.5

PERFORATING SYSTEMS WITH CAPSULE CHARGES

This procedure is designed to identify and quantify all debris left in the well bore by a capsule gun system. Since the well bore environment greatly affects the size of the debris, it is important to run all tests under the same conditions. Debris is described as all solid material from the perforating gun that remains in the well bore after the expended gun system is retrieved.

5.5.1

Test Requirements

The following requirements must be met to properly conduct this test: 1. Standard field equipment available to any customer must be used. 2. The gun assembly must have a minimum of one linear foot of perforations. 3. The linear gun section must be fully loaded to the maximum shot density. 4. The assembled gun section can be cut from a standard length strip, but must include all accessories and perforating hardware that would be used in a standard API Section 1 test. 5. If different hardware is used to attach charges in different shot phasings, then each of these must be tested and reported separately. 6. The test must be conducted in a closed vessel under 5,000 psi water (potable water) pressure at ambient temperat ure. 7. With the exception of the perforations, the chamber must remain sealed after the gun section has been fired. If the vessel ruptures the test is considered to be invalid. 8. The charges used must be standard and come from a single production lot of not less than 300 each for HMX and higher temperature charges, and not less than 1,000 each for lower temperature charges, as defined in 1.4.

5.5.2

Test Procedure

Follow the steps below to conduct the debris test: 1. Place the loaded gun section in the pressure vessel in the same position it would be in if it were being fired in a standard API Section 1 target. 2. Close the vessel and pressurize to 5,000 psi 3. Fire the gun section. If it is necessary to tr ansport the pressure vessel to another area to open it, it must be done in a manner to contain all the debris. 4. Open the vessel and retrieve all the solid debris. 5. Remove and discard all the retrievable carrier material. 6. Detonator wires and fragments, and detonating cord remnants that are common to all systems can also be removed. 7. Thoroughly dry the remaining debris at 150 to 200°F for a minimum of 1 hour before weighing and measuring. 8. All measuring and weighing equipment must be properly calibrated.

5.5.3

Debris Volume Measurements

Use the guidelines below to measure and record the test data to the nearest cc: 1. Use an appropriately sized graduated measuring cylinder to determine the volume of debris. 2. The graduated cylinder must meet ASTM E 1272 (Standard Specification for Laboratory Glass Graduated Cylinders) requirements for accuracy. 3. The graduated cylinder may be tapped lightly until a constant volume is achieved. 4. The volume must be reported as the total amount per charge and the total amount per linear foot of perforations.

5.5.4

Debris Weight Measurements

Use any standard scale with the capability to measure to the nearest gram. Weigh and record the amount per charge and the total amount per linear foot, on the data sheet (see Figure 21) to the nearest gram.

5.5.5

Average Weight of Gun Debris Per cc

Divide the total gram weight of debris by the total cc and record on the data sheet (see Figure 21) to the nearest 0.1 gram per cc.

52


5.5.6

Debris Sieve Size Analysis

Determine sieve size by measuring and recording all solid debris generated by the expended gun section. Measurements should be made according to ASTM E 389-03 (Standard Test Method for Particle Size or Screen Analysis at No.4 Sieve and Coarser, for Metal-Bearing Ores and Related Materials). Record the percentage by weight retained on each of the U.S. Sieves listed on the data sheet (see Figure 21). Also identify the type of material retained on each sieve.

5.5.7

Data Reporting

Use the “Gun Debris Data Sheet for Capsule Charge Perforating Systems” as the standard reporting form. See Figure 21.

6

EVALUATION OF PERFORATOR SYSTEMS TO DETERMINE SWELL

6.1 INTRODUCTION This section is intended to provide a test procedure to be followed for testing, measuring, and recording of the gun body swell of a perforator system. Swell testing does not have to be witnessed by an API witness.

6.2

SHAPED CHARGE SELECTION

The shaped charges required for this test shall be standard shaped charges that meet their current manufacturing specifications. The charges may be pulled from the manufacturing line, or made by the engineering group. The charge lot quantity and charge age shall be in accordance with Section 1.4.

6.3


The perforating system to be tested shall consist of standard field equipment. The entire length of the perforator system shall be fully loaded with no blank spaces. The minimum length of active gun (loaded length) shall be no less than 4 ft.

6.4

CASING SELECTION

Casing selection is based on the outer diameter of the perforator system being tested, as shown in Table 3. The length of the casing shall be, at a minimum, equal to the length of the perforator system being tested. Casing reuse and replacement shall be at the sole discretion of the company performing the testing. If the perforator system is rated to be shot in air, then casing is not required.

Table 3—Casing Selection Requirements Gun Size, OD Casing Size, OD Casing Weight, in. in. lb/ft

Casing, API Grade

51/2 in. 95/8 in.

L-80 L-80

4 in. or smaller Larger than 4 in.

17.0 47.0

Perforator system swell may be combined with API Section 1; and if so, Section 1 casing is acceptable and shall be noted on the data sheet.

6.5

TESTING FLUID

Fresh water shall be the standard fluid used during the testing. If a gun is to be rated as able to shoot “dry” then air at atmospheric pressure shall be used. Testing fluid type shall be recorded on the data sheet.

6.6

PRE-TEST MEASUREMENTS

The OD of the perforator system shall be measured in increments of no more than 1ft along the entire length of the perforator system. The perforator system shall then be rotated approximately 90° and the measurements shall be repeated. The measurements shall be conducted using two 18 in. minimum flat parallel surfaces placed on each side of the perforator system. Surfaces must be held within 0.005 in. parallel along entire length of surface. Measurements shall be taken between the two parallel surfaces at a minimum of 1 ft increments. Measurements shall be reported to the nearest 0.01 in. All measurements shall be recorded on the data sheet.


6.7

53


TEST SETUP

The fully loaded perforator system shall be shot as it is normally positioned in the casing. Record the system positioning on the data sheet (centralized or decentralized). The casing shall be completely filled with the appropriate testing fluid.

6.8

POST TEST MEASUREMENTS

The OD of the perforator system shall be measured in increments of no more than 1ft along the entire length of the perforator system. The perforator system shall then be rotated approximately 90° and the measurements shall be repeated. The measurements shall be conducted using two 18 in. minimum flat parallel surfaces placed on each side of the perforator system. Measurements shall be taken between the two parallel surfaces at a minimum of 1 ft increments. Measurements shall be reported to the nearest 0.01 in. All measurements shall be recorded on the data sheet. Perforator systems of 27/8 in. diameter and smaller shall be drifted using a drift gauge with a minimum length of 18 in. (see Figure 22). Perforator systems larger than 27/8 in. diameter may be drifted if desired. The perforator system should pass through the drift gauge without the use of excessive force. If any burrs or debris are dislodged by the drift gauge, it shall be recorded on the data sheet.

18.0 in. Minimum 2x 0.50 in. Approx. 2x 15° Approx. OD ID

ID (in.) Nipple No-Go ID – 0.005

ID Tolerance (in.) +0.000 –0.005

OD Minimum (in.) ID + 0.5

2x 45° x 0.03 Approx.

Figure 22—Drift Gauge Drawing 6.9

DATA RECORDING AND REPORTING

Information shall be recorded in the Hardware Description, Charge Description, Perforator System Drift Data and Test Configuration sections of the data sheet (see Figure 23). The pre-shot OD and post-shot OD measurements for each location shall be recorded in the Perforator System Swell Measurements section of the data sheet (see Figure 23).

7

REFERENCES 1. API RP 56 Second Edition 2. ASTM C 109 3. ASTM A 36

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s m e t s y S g n i t a r o f r e P r e i r r a C w o l l o H r o f a t a D l l e w S — t e e h S a t a D — 3 2 e r u g i F

APPENDIX A—API REGISTERED PERFORATOR SYSTEMS Applications for Perforator System Registration are available from API. To obtain an application, please access the API Certification Programs website http://www.api.org/certification-programs/witnessing-programs/perforator-witnessing-program.

55

09/06

API RP 19B 2nd Ed.2006 + A1 & A2.2014 Recommended Practices for Evaluation of Well Perforators

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