Project Report_ Summer Training@Ankleshwar, ONGC

Report on Summer Training at ONGC Ankleshwar Asset

Department of Petroleum Engineering, Indian School of Mines, Dhanbad

SUBMITTED BY:

Sangita Kumari

14MT000088

Rohit Kumar Saw

14MT000100

Prabhakar Kushwaha

14MT000106

Pankaj Mishra

14MT000171

Arunangshu Chakraborty

14MT000174

Manoj Kumar

14MT000195

Sidharth Gautam

14MT000226

Inderpreet Singh

13MT000229

Vijay Singh

14MT000238

Ramaswamy Gautam

14MT000240

Madhusmita Basumatary

14MT000278

Harsh Shah

14MT000286

Rakesh Kumar Pandey

14MT000287

Moupiya Mallick

14MT000466

Barasha Deka

14MT000467

Prathibha Pillai

14MT000474

Shashikala Shashikal a Kumari

14MT000477

Chandana Roy

14MT000501

SUBMITTED BY:

Sangita Kumari

14MT000088

Rohit Kumar Saw

14MT000100

Prabhakar Kushwaha

14MT000106

Pankaj Mishra

14MT000171

Arunangshu Chakraborty

14MT000174

Manoj Kumar

14MT000195

Sidharth Gautam

14MT000226

Inderpreet Singh

13MT000229

Vijay Singh

14MT000238

Ramaswamy Gautam

14MT000240

Madhusmita Basumatary

14MT000278

Harsh Shah

14MT000286

Rakesh Kumar Pandey

14MT000287

Moupiya Mallick

14MT000466

Barasha Deka

14MT000467

Prathibha Pillai

14MT000474

Shashikala Shashikal a Kumari

14MT000477

Chandana Roy

14MT000501

CERTIFICATE

This is to certify that Miss Sangita Kumari , Roll no. 14MT000088 , M. Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11th May to 5th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT AT ONGC, ANKLESHW A NKLESHWAR AR ASSET”. ASSET” .

Under the Guidance of

Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),

Field Manager, Area IV

Artificial Lift Section,

ONGC Ankleshwar Asset


CERTIFICATE

This is to certify that Mr. Rohit Kumar Saw , Roll no. 14MT000100, M. Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11 th May to 5th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT ONGC, ANKLESHWAR ASSET”.


Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),





CERTIFICATE

This is to certify that Mr. Prabhakar Kushwaha , Roll no. 14MT000106 , M. Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11th May to 5 th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT ONGC, ANKLESHWAR ASSET”.


Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),





CERTIFICATE

This is to certify that Mr. Pankaj Mishra , Roll no. 14MT000171 , M. Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11 th May to 5th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT ONGC, ANKLESHWAR ASSET”.


Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),





CERTIFICATE

This is to certify that Mr. Arunangshu Chakraborty , Roll no. 14MT000174 , M. Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11th May to 5 th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT ONGC, ANKLESHWAR ASSET”.


Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),





CERTIFICATE

This is to certify that Mr. Manoj Kumar , Roll no. 14MT000195, M. Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11 th May to 5th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT ONGC, ANKLESHWAR ASSET”.


Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),





CERTIFICATE

This is to certify that Mr. Sidharth Gautam , Roll no. 14MT000226 , M. Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11 th May to 5th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT ONGC, ANKLESHWAR ASSET”.


Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),





CERTIFICATE

This is to certify that Mr. Inderpreet Singh , Roll no. 13MT000229 , M. Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11th May to 5th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT ONGC, ANKLESHWAR ASSET”.


Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),





CERTIFICATE

This is to certify that Mr. Vijay Singh , Roll no. 14MT000238 , M. Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11 th May to 5th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT ONGC, ANKLESHWAR ASSET”.


Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),





CERTIFICATE

This is to certify that Mr. Ramaswamy Gautam , Roll no. 14MT000240 ,

M.

Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11th May to 5 th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT ONGC, ANKLESHWAR ASSET”.


Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),





CERTIFICATE

This is to certify that Miss Madhusmita Basumatary , Roll no. 14MT000278 , M. Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11th May to 5 th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT ONGC, ANKLESHWAR ASSET”.


Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),





CERTIFICATE

This is to certify that Mr. Harsh Kalpesh Shah , Roll no. 14MT000286, M. Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11 th May to 5th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT ONGC, ANKLESHWAR ASSET”.


Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),





CERTIFICATE

This is to certify that Mr. Rakesh Kumar Pandey , Roll no. 14MT000287 , M. Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11th May to 5 th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT ONGC, ANKLESHWAR ASSET”.


Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),





CERTIFICATE

This is to certify that Miss Moupiya Mallick , Roll no. 14MT000466 , M. Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11 th May to 5th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT ONGC, ANKLESHWAR ASSET”.


Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),





CERTIFICATE

This is to certify that Miss Barasha Deka , Roll no. 14MT000467 , M. Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11 th May to 5th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT ONGC, ANKLESHWAR ASSET”.


Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),





CERTIFICATE

This is to certify that Miss Prathibha Pillai , Roll no. 14MT000474, M. Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11th May to 5th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT ONGC, ANKLESHWAR ASSET”.


Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),





CERTIFICATE

This is to certify that Miss Shashikala Kumari , Roll no. 14MT000477 , M. Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11 th May to 5th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT ONGC, ANKLESHWAR ASSET”.


Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),





CERTIFICATE

This is to certify that Miss Chandana Roy , Roll no. 14MT000501 , M. Tech (Petroleum Engineering) of Indian School of Mines, Dhanbad has successfully completed summer training at ONGC Ankleshwar Asset, during the Period of 11 th May to 5th June 2015 and submitted project report titled “REPORT ON SUMMER TRAINING AT ONGC, ANKLESHWAR ASSET”.


Shri S. Kujur

Shri Gairik Das

Chief Engineer (P),

Chief Engineer (P),





Summer Training Report

ACKNOLEDGEMENT I, wish to thank OIL & NATURAL GAS CORPORATION Ltd. Ankleshwar Asset for allowing to conduct training program at their premises and for providing all the needful facilities required for completion of the entire program.

I would like to express our sincere gratitude towards our mentor Mr Gairik Das – CE(P) , Artificial Lift , Surface Team & Mr S. Kujur – CE(P) , Field Manager , Area IV for his continuous guidance and for enlighting us with v ital knowledge throughout the program. Working under his guidance has been a privilege and a fruitful learning experience.

I am also thankful to Mr Kalyan Chakarbarthy who took great zeal in arranging lectures and field visits during the course of our training with the surface team. I would also like to thank Mr KRVS Prasad and Mr D.R. Sharma of Logging Services for providing us with all the necessary help and for guiding us throughout the preparation of this report. I express my deep gratitude to Mr. Ravi Pratap Singh of CMT and Mr Ayush , Mr Abhishek & Mr Nishant and Mr. Anup of Artificial Lift department for sharing their valuable knowledge with us without which the completion of this project would have been rather impossible. I would also like to thanks to WCT team, WSS Team, Work over & Fishing Team of PTTYS Gandhar for arranging field visits and providing us with valuable knowledge about Workover, Completion & Stimulation operation.

I would like to thank Head of Petroleum engineering department ISM, Dhanbad Prof. V. P. Sharma and course coordinator Dr. T K Nayia for their support with which we were able to complete our summer training successfully. At last, I express my deep gratitude to those who have helped and encouraged us in various ways in carrying out this project work. I would like to extend my thanks and would like to acknowledge the ONGC personnel for sharing their valuable knowledge with us without which the completion of this project would have been rather impossible.


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Table of Contents 1

Introduction ........................................................................................................................ 1 1.1

Cambay Basin ............................................................................................................. 1

1.2

Ankleshwar Asset........................................................................................................5

1.2.1 2

Well Logging......................................................................................................................7 2.1

Introduction ................................................................................................................. 7

2.2

Types of log ................................................................................................................. 9

2.2.1

Open Hole Logging.............................................................................................. 9

2.2.2

Cased Hole Logging .......................................................................................... 10

2.3

Theory of Logging .................................................................................................... 11

2.3.1

Cement Bond Log (CBL-VDL) ......................................................................... 11

2.3.2

Sonic (CBL/VDL) Principle .............................................................................. 11

2.3.3

Production Logging ........................................................................................... 12

2.4

3

Ankleshwar field .................................................................................................. 5

Interpretation of Open Hole Log ............................................................................... 16

2.4.1

Fundamentals of Log Interpretation...................................................................16

2.4.2

Combinable Magnetic Resonace (CMR) ...........................................................17

Well Services ....................................................................................................................18 3.1

Introduction ............................................................................................................... 18

3.2

Workover................................................................................................................... 19

3.2.1

What Is Workover .............................................................................................. 19

3.2.2

Fishing Operations ............................................................................................. 19

3.3

Well Completion and Testing ...................................................................................25

3.3.1

Surface Equipments ........................................................................................... 25

3.3.2

Downhole equipments .......................................................................................27

3.4

Well Stimulation Services ......................................................................................... 30

3.4.1

Coiled tubing unit .............................................................................................. 31


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Summer Training Report 3.4.2 4

Operations Performed By WSS Section ............................................................ 32

Crisis Management ........................................................................................................... 33 4.1

Kick ........................................................................................................................... 33

4.1.1

Causes of Kicks.................................................................................................. 34

4.2

Well Control Methods ............................................................................................... 34

4.3

Blowout Prevention Equipments ............................................................................... 34

Drilling Spools..................................................................................................................36 Diverter System....................................................................................................................36 Choke and Kill Lines............................................................................................................ 36 Choke Manifold.................................................................................................................... 36 Hydraulic Power Package (Accumulators) .......................................................................... 37 5

Artificial Lift.....................................................................................................................38 5.1

Electrical Submersible Pump .................................................................................... 39

5.2

Sucker Rod Pumping ................................................................................................. 41

5.3

Gas Lift......................................................................................................................47

5.4

Hydraulic Pumping ................................................................................................... 48

5.5

Jet Pumping...............................................................................................................49

5.6

Progressive Cavity Pumping ..................................................................................... 50

5.7

Artificial Lift - Comparison ...................................................................................... 52


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List of Figures FIGURE 1: R OCK UNITS AND THEIR REFERENCE SECTION IN CAMBAY BASIN................................ 2 FIGURE 2: LITHOSTRATIGRAPHY OF CAMBAY BASIN .................................................................... 3 FIGURE 3: TYPES OF TRAPS DISCOVERED IN CAMBAY BASIN ........................................................4 FIGURE 4:A NKLESHWAR ASSET .................................................................................................. 6 FIGURE 5: FIELD TRUCK .............................................................................................................. 7 FIGURE 6: OPEN HOLE TOOLS ....................................................................................................10 FIGURE 7: CBL/VDL VARIATION ............................................................................................. 11 FIGURE 8: CALIPER TOOL .......................................................................................................... 15 FIGURE 9: EXAMPLE OF WELL LOG ............................................................................................ 16 FIGURE 10: SPIRAL GRAPPLE .....................................................................................................23 FIGURE 11: SPEARHEAD ............................................................................................................24 FIGURE 12: MILLING TOOLS ...................................................................................................... 24 FIGURE 13: TYPES OF PACKER ................................................................................................... 27 FIGURE 14: HYDRAULIC PACKER ...............................................................................................30 FIGURE 15: SLIDING SLEEVE ..................................................................................................... 30 FIGURE 16: COILED TUBING UNIT ..............................................................................................31 FIGURE 17: A NNULAR BOP ........................................................................................................35 FIGURE 18: ESP ........................................................................................................................ 40 FIGURE 19: CONVENTIONAL SRP ............................................................................................... 42 FIGURE 20: LUFKIN MARK II UNIT ............................................................................................. 43 FIGURE 21: SRP INSTALLATION SEQUENCE ............................................................................... 44 FIGURE 22: WALKING BEAM AND SAMSON POST ....................................................................... 44 FIGURE 23: COUNTERWEIGHTS ................................................................................................. 45 FIGURE 24: CRANKSHAFT ......................................................................................................... 45 FIGURE 25: SPECIFICATION OF SRP IN FIELD .............................................................................46 FIGURE 26: HORSEHEAD AND BRIDLE ....................................................................................... 46 FIGURE 27: JET PUMP ................................................................................................................ 50 FIGURE 28: PCP COMPONENTS ..................................................................................................51


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List Of Tables TABLE 1: TYPES OF LOG AND APPLICATIONS................................................................................ 8 TABLE 2: OPEN HOLE LOGS .........................................................................................................9 TABLE 3: K ICK CONTROL .......................................................................................................... 33 TABLE 4: FACTORS FOR SELECTION OF ARTIFICIAL LIFT ............................................................ 38 TABLE 5: SELECTION CRITERIA FOR VARIOUS ARTIFICIAL LIFT TECHNIQUES.............................. 52


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Chapters 1

Introduction ........................................................................................................................ 1

2

Well Logging......................................................................................................................7

3

Well Services ....................................................................................................................18

4

Crisis Management ........................................................................................................... 33

5

Artificial Lift.....................................................................................................................38


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1 Introduction 1.1 Cambay Basin 

Discovery: 1958



Located on the western margin platform of Indian craton



Area 56,000 sq. km between 21° - 25°N and 71°30' - 79°30'E



Intracratonic basin in the form of N – S (NNW – SSE) trending graben flanked in the East by Aravalli and Deccan Plateau and in the West by Saurashtra plateau



Age: Tertiary with mainly clastic sediments ranging from Eocene to Recent deposits



Two stage structure development 

Earliest during Jurassic



Later during Late Cretaceous when Tertiary sedimentary basin came into existence as a result of crustal tension following basaltic lava extrusion



Five tectonic blocks in the basin 

Sanchar – Patan



Mehsana – Ahmedabad



Tarapur – Cambay



Jambusar – Broach

 

Narmada – Tapti

Stratigraphy 

Basin is almost covered with Sabarmati alluvium, and alluvium of Mahisagar, dadhar, Narmada, and Tapti rivers



Shallower towards north



8000m thick tertiary sediments overlie the Deccan Trap

 

Neogene succession comprises of six distinct units of sandstone And shale Youngest unit, Jambusar formation (Pleistocene) is unconformably overlain by Gujarat alluvium (Pleistocene / Holocene)


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F IGURE 1: R OCK UNITS AND THEIR REFERENCE SECTION IN CAMBAY BASIN



Hydrocarbon habitat in Cambay Basin 

Cambay Shale is the main source rock in this basin.



The organic matter content averages to 2.5% and mainly of sapropelic and humic in nature.



The sandstone and siltstone of Ankleshwar, Kalol and Kadi Formations are the main reservoir rocks in this basin.



The traps are structural, stratigraphic and combination type in this basin. Cambay Shale acts as cap rock for hydrocarbon deposits in Kadi Formation and Vagad Khol Formation, whereas in the northern part, Tarapur Shale acts as cap rock.



Telwa Shale of Ankleshwar Formation and Kanwa Shale in South of Mahisagar river also serve as cap rock.


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F IGURE 2: L ITHOSTRATIGRAPHY OF CAMBAY BASIN


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F IGURE 3: T YPES OF TRAPS DISCOVERED IN CAMBAY BASIN


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1.2 Ankleshwar Asset Ankleshwar is the first Asset where Oil and Natural Gas Corporation discovered oil in 1960. It’s also the largest asset located in South of Gujarat in Bharuch district. Ankleshwar asset is spread along Contiagal, Kosamba, Kim, Jalod, Rajpadi, Gandhar, Dahej, Nada, Kavi, Dabka, Alamgir oil fields. The Asset has two main fields: Ankleshwar field and Gandhar field. While Ankleshwar is a mature field, Gandhar is a relatively new field which was discovered in 1984.

1.2.1 Ankleshwar field Ankleshwar oil field is the biggest and the oldest oil-field of Oil and Natural Gas Corporation Ltd. This is oil field is located at a distance of 6 km SSW of Ankleshwar Town in Gujarat State. This field is situated in Narmada-Tapti Tectonic Block of Cambay Basin and having an areal extent of 32.47 sq. km. Geological Survey of India started exploration of oil and gas in the field as early as 1930’s. Subsequently the geologists of Oil and Natural Directorate of India mapped the area and carried out Gravity Magnetic Survey during the year 1957-1958. Seismic survey was carri ed out in the year 1958-1959. An exploratory test well was released for confirming the hydrocarbon potential and the well was drilled in the year 1960 to a depth of 1969 m. Hydrocarbon accumulations have been discovered in arenaceous reservoirs within Cambay shale, Ankleshwar, Dadhar and Babaguru formations. Major oil pools are found in multi-layer sandstone reservoirs within Hazadand Ardol members of Ankleshwar formation. The sandstones of Ankleshwar formation represent series of delta front sands of the pro Narmada Delta developed in the South Cambay Basin. 1.2.1.1 About the Field 

Field discovered in 1960.



Put on production since 1961.



Located at a distance of 15 km. from Ankleshwar town.



Part of Narmada Block of Cambay Basin.



Spread over an area of approx. 32.27 sq. km.


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

Hydrocarbon entrapment in multi-layered sandstone reservoir.

F IGURE 4:A NKLESHWAR ASSET

1.2.1.2 Geology 





E-W trending doubly plunging anticline, cut by reverse fault towards South. Number of small fluid anomaly faults within main field. Deltaic deposition comprising of distributaries mouth bars and channels.


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

Sand entry from North and North-East.



Grade into prodelta shale towards West.



Sand bodies separated by transgressive shales.

2 Well Logging 2.1 Introduction Well logging is a continuous and systematic recording of physical parameter versus depth in borehole. The recorded information on film or paper is called a well log. Logs can also be preserved in “CDs” or “DAT” tapes. Wireline logs or well logs are obtained by downhole logging tools which are known as ‘Sonde’ lowered into the wells by means of a cable. Measurements are transmitted up through the cable to a recording unit mounted on a logging truck. The wire line logs are usually obtained after an interruption (or termination) of drilling activity. Geophysical well logging is necessary because core sample during drilling leaves a very less record of formation encountered.

F IGURE 5: FIELD TRUCK


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T ABLE 1: T YPES OF LOG AND APPLICATIONS

Category

Types of Log

Application

Measured, Units

of Logs

Mechanical

Parameter

Caliper

Diameter of hole

The variation in diameter of a borehole provides information on the lithology, permeability and porosity.

Electrical

S.P

Spontaneous

Correlation, Lithological indicator,

potential mV/div

Determination of volume of shale and formation water salinity, Identification of porous and permeable beds.

Focused tools

Resistivity, ohm-m

Micrologs

Resistivity, ohm-m

Effective determination of formation resistivity. Resistivity of mud cake, Resistivity of invaded zone,

Induction

Nuclear

Large,

Conductivity of

Measurement of formation

medium and

formation

resistivity

small spacing

(millimhos/m)

Gamma Ray

Natural

Sensitive to presence of clay,

Radioactivity CPS

Correlation

or API Gamma –

Reaction to Gamma

Determination of Density and

Gamma

ray bombardment

Porosity

CPS or API Neutron

Reaction to Neutron

Determination of Total Porosity

bombardment CPS or API


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Summer Training Report Acoustic

Single or

Transit time ,

Double

Microsecond/foot

Porosity for valves greater than 5 %

receiver system

2.2 Types of log Basically two types of logging are done: 

Open hole logging



Cased hole logging

2.2.1 Open Hole Logging Logs recorded in open hole are basically used for formation evaluation and identification of lithology of the subsurface strata and estimating the thickness, porosity, permeability and hydrocarbon saturation on the beds. This process is done aft er the drill string is pulled out from the bore hole and before the casing is lowered inside.

T ABLE 2: OPEN HOLE LOGS

Electrical logs

Self Potential log Resistivity log

Radioactive logs

Gamma ray log Neutron log Density log

Other logs

Sonic log Temperature log Caliper log Dip meter log Formation Tester (SFT or MDT) Side wall core


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Summer Training Report Formation Micro resistivity image tool (FMI) Combinable

Magnetic

Resonance

tool

(CMR)

F IGURE 6: OPEN HOLE TOOLS

2.2.2 Cased Hole Logging The logging carried out in the cased wells is called Cased Hole Logging. The main application of cased hole logging are: 1. Completion Services: 

To see cement quality



Control log for perforation and other services

2. Reservoir monitoring: 

To detect water flooding of any zone



To detect rise in fluid contacts



To locate bypass hydrocarbon

3. Production Logging: 

To detect channelling behind casing



To detect contribution from different zones


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

To detect type of fluid produced

2.3 Theory of Logging 2.3.1 Cement Bond Log (CBL-VDL) The cement bond tool consist of an acoustic transmitter, two receiver R1, R2 (3 feet , 5 feet) CBL / VDL works on the principle of acoustic reflectivity.

The evaluation of cement bond quality comprises:

1. Evaluation of quality of cement behind pipe (amplitude in mV) 2. Evaluation of quality of cement to formation (VDL – Variable Density Log) Micro or very thin fluid layer between casing and cement will give a high amplitude signal corresponding to no contact, if casing is pressurised the micro annulus will close and low amplitude will result. (The attenuation is inversely proportional to the casing thickness and directly proportional to the solid density).

2.3.2 Sonic (CBL/VDL) Principle As the sound travels at different velocities in different mediums, therefore their arrival times to receiver will be different. The orders of these arrivals are: 1. The casing arrival 2. The formation arrival 3. The fluid arrival

F IGURE 7: CBL/VDL V ARIATION

These arrivals depend on the factors such as:


Page | 11

Summer Training Report a. Formation velocities b. Open hole size c. Casing size The basic bond log consists of an acoustic transmitter (or sound source) and an acoustic receiver. The transmitter generates a sound pulse which travels through several different sound paths to the receiver. The three most obvious paths observed are casing path, the formation path, and the fluid path. Because sound travels at different velocities in different mediums, the sound waves from the three paths normally arrives at three different times.

2.3.3 Production Logging Production logging is the wire line logging services in cased hole in dynamic well condition. Logs recorded in Production logging are used basically to diagnoses production / injection well problems. The objective of production logging is to determine what fluid are entering (or leaving) the well bore, through which depth intervals and which part of the stratigraphic column is the fluid source. Production logging provides down hole measurements of fluid properties on a zone by zone basis to yield information about the types of fluid with in and near the well bore. The conventional tools used for production logging are: 



Correction tool o

Gamma Ray

o

CCL

Flow Behind Casing o



Pressure Data o





Pressure tool

Fluid Identification Tool o

FDT (Fluid Density Tool)

o

Hydro Tool (Water Hold Up)

Rate of Fluid Flow o



Temperature tool

Flow Meter

Down Hole Tool

The down hole tools in use with Halliburton LOG-IQ Production Logging unit can be categorized as


Page | 12




Telemetry tool



Analog tool



Auxiliary tool

XTU



Production Logging tools require an XTU wireline telemetry tool to be attached on the top of the tool string. The Downhole controller is an intelligent bridge between the ultrawire tool bus and the Sondex Ultra link telemetry system. It serves both as a communication interface and as a programmable logging controller. The Purpose of the XTU Downhole controller is: o

To collect data from the tools on the Ultrawire tool bus and to transit this data to the surface via the ultralink line automatically or under user control

o

To facilitate bi directional communication between the surface and individual ultrawire tools

o

To convert high voltage DC power from the Ultrali nk line to supply the lower voltage tools on the ultrawire tool bus

The tools those operate under the control of XTU telemetry: 

QPC – Quartz Pressure & Casing Collar Locator Tool



PGR – Production Gamma Ray tool



FDR – Fluid Density Radioactive Tool



CTF – Capacitance, Temperature & Flow meter tool

1. QPC – Quartz Pressure & Casing Collar Locator Tool

It provides 

A continuous log of borehole fluid pressure



A record of reservoir pressure draw down and build up data during flowing tests



Location of casing collar for depth control

2. PGR – Production Gamma Ray tool

Production gamma detection provides 

Lithology identification



Depth correlation



Identification of Radioactive scale, possible sign of water entry.



Monitoring of Radioactive flow tracer


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Summer Training Report 3. FDR – Fluid Density Radioactive Tools

The purpose of the FDR is to fluid density of a sample as it flows through the tool. The average density of this volume is measured whether the flow is single or multiphase. Application: 

Multiphase production profiling



Fluid Identification



High fluid flow rates

4. CTF – Capacitance, Temperature & Flow Meter Tool

Purpose: To provide a continuous log of fluid capacitance (water holdup), Temperature, Flow rate and direction. Application: 

Fluid composition from average dielectric constant.



Location of leaks cross flow by temperature respo nse.



Quantitative measurements of flow rate in casing & tubing.



Production and Injection log Interpretation.



Cement top determination.

Auxiliary Tools : 

The auxiliary equipment provided with Production Logging Units



Roller Centralizer for centralization of tools in well.



Sinker Bar – to provide weight to the string for easy slide in the well.



Bull Nose – Required at string bottom in case CTF is not attached at the string bottom.



Centralizer (Bow Spring) – to provide centralization for CBL tool in well.

2.3.3.1 Sonic or Acoustic Log

Sonic log is the measurement of acoustic wave propagation in the sub surface. The sonic log is based upon the propagation of sound wave through the formation. The speed of the sound wave depends upon the presence of fluid in the pores of rock. Thus the wave speed or its travel time is a measure of formation porosity. It is also used for fracture identification as well as for lithology identification. Application:


Page | 14




To determine the porosity in the reservoir



To compute secondary porosity like vuggs in carbonate reservoir and fracture in traps/basement



As an aid in lithological determination, when it combined with other porosity logs.



This can be used to study compaction in sand, shale sequence

2.3.3.2 Caliper Log

Borehole diameter is measured by the calliper tool that records continuous variation of borehole diameter with depth. Shapes of borehole cross section at different depth varies from circular to elliptical, conical or any other configuration. It is also an indicator of lithology. During drilling, mud cake is formed against the permeable bed that causes the reduction in

F IGURE 8: C ALIPER TOOL

borehole size , on the other hand swelling of non-permeable shale give rise to caving which results a large bore hole . A caliper is also useful in determining the amount of cement for cementation. 2.3.3.3 Sidewall Coring

A core taken from the side of the borehole, usually by a wireli ne tool. Sidewall cores using may be taken percussion or mechanical drilling. Percussion cores ar e taken by firing hollow bullets into the formation. The bullets are attached to the tool by fasteners, and are retrieved, along with core inside, by pulling up the tool and the fasteners. Percussion coring tool typically holds 20 to 30 bullets, but two or three tools can be combined on one run in hole.

Mechanical tool use hollow rotary drills to cut and then pull out core plugs. Up to 75 plugs can be recovered on one run.


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2.4 Interpretation of Open Hole Log 2.4.1 Fundamentals of Log Interpretation Log interpretation is needed to evaluate a reservoir and its porosity, hydrocarbon saturation, thickness, area, permeability, geometry, formation temperature and pressure, and lithology can play important roles in evaluation, completion and production of a reservoir.

F IGURE 9: E XAMPLE OF WELL LOG

Above well log data shows different logs, Graph in first track shows Gamma ray response, its deviation towards shows Sandstone, in second track gives Resistivity, high resistivity with separation shows it may be the reservoir rock and corresponding low density and high neutron log suggest that this bed is a reservoir rock containing Oil and Gas. It is accomplished by determining the following parameters: 

Detection of permeable beds and estimation of their true thickness



Determination of formation water r esistivity, R w



Determination of true formation water resistivity, R t



Determination of true formation factor (F) and porosity (Φ)



Determination of water saturation (S w)


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

Determination of effect of clay



Detection of presence of hydrocarbon in permeable bed



Estimation of porosity and water saturation



Tortuosity constant (a)



Cementation factor (m)



Saturation exponent (n)

2.4.2 Combinable Magnetic Resonace (CMR) The high resolution CMR tool enhances the precision of nuclear magnetic resonance (NMR) logging. Measurements for determining your reservoir’s permeability, water cut and hydrogen pore volume are obtained at logging speeds 3 to 5 times faster than those of conventional NMR tools. The result is much greater accuracy in productivity estimation along with improved completion design for optimizing well performance and return on investment.


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3 Well Services 3.1 Introduction Well services group is a pioneer in its field covering the entire gamut of activities consisting of workover operations, well testing and completions and well stimulation services. Having a strong and experienced man power of more than 700 persons, this group has rose to the occasion to meet the multidimensional challenges in day to day activities with utmost concern in safety aspects. This group comprises of three major sections viz. Work over Section, well testing and well stimulation services.

Workover The workover operation play the major role in sustaining the oil production from the mature fields of eastern region. These operations are required for revival of sick oil, gas and water injection and effluent disposal wells. The workover section is the flag ship of well services group. Water shut off, zone transfer, casing repair, sand control jobs, servicing of of effluent disposal wells, servicing of wells on artificial lifts, installation of artificial lifts systems etc.

Well completion and testing This section comprises of well testing and downhole sections. Well testing is the first and foremost major activity under taken after drilling a well success of which decides all future oil production activities. All identified prospective objects are individually perforated and completed using downhole equipments and the well is activated. Flow studies are then carried out to measure the flow rates to estimate the reservoir potential. The wells are then suitably completed and put in production.

Well stimulation services Came into being in its present entity to fulfill the need of stimulation and specialized services for enhancing oil and gas production.WSS provides stimulation services such as hydraulic fracturing, acidization ,surfactant/solvent treatment and specialized services like coil tubing services, gravel pack, nitrogen application, water shut off, hot oil circulation, sand gel plug, tubular scouring and cleaning etc. This section has also actively participated in crises management activities like blow out control, trouble shooting in trunk lines operations etc.


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3.2 Workover 3.2.1 What Is Workover The term workover is used to refer to any kind of oil well intervention operations i.e. the workover operation includes one or more of a remedial operations on a producing well in order to increase production. Workovers rank among the most complex, difficult and expensive types of well work. Workover operations are performed if the completion of a well is terminally unsuitable for the job at hand, the production tubing may become damaged due to operational factors like corrosion to the point where well integrity is threatened, downhole components such as tubing, downhole retrievable safety valves or the artificial lift may have malfunctioned, needing replacement or due to changing reservoir condition which make the completion unsuitable. Why Workover Is Necessary 

To maintain the well in optimum producing condition.



Solving specific well and reservoir problems.

Workover operations performed 

Through tubing perforation



Zone transfer

3.2.2 Fishing Operations Fishing refers to the application of tools, equipment and techniques for removal of lost or stuck objects from the well bore. The term “fishing” is taken from the times of the earlier cable tool drilling when the crew simply put a hook on a line and attempted to catch the wire line when it would break so that the tool could be retrieved. Over the years, with advancement in drilling, completion and work over, fishing has also evolved greatly as an art and science of removing broken or stuck equipment or small non-drillable materials from the well bore. The fishing operations can mainly be categorized into: 

Open hole operations are those in which the fishing tools are run in open hole to

retrieve a fish present in open hole. 

Cased hole wherein the fishing operations are carried out in cased hole.



Through tubing Through-tubing fishing takes place through the restriction of the

smaller-sized tubing. Through-tubing fishing applications have grown dramatically with the increased use of coiled tubing as a conveyance method. ONGC Ankleshwar Asset

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Summer Training Report 3.2.2.1 Fishing Tools

The key enabling technologies for successful fishing operations are cutting, milling, catching/engaging and pulling. Based on the kind of fishing operation, a variety of fishing tools are available. The use of appropriate fishing tool for any particular job will largely depend on the type of fish in the hole, whether the fish is stuck or free, whether it is in an open hole or in a cased hole, the condition of the hole at the site of break and the condition of the top of the fish. Each fishing job is unique but there are some basic tools such as safety joint, bumper sub, hydraulic jar and heavy weight drill pipes that are used in most jobs along with appropriate fishing tool and drill pipe work string. Based on intended application, the fishing tools can be classifi ed into: A. External Catch Tools The external catch tools engage a fish on its outside body. Some of the commonly used external catches fishing tools are: i.

Overshot

The overshot is one of the most widely used fishing tools. It is a highly versatile and efficient tool. There are several different types of over shots; however, each overshot is designed to engage a specific size of tubing, pipe, coupling tool joint, drill collar or smooth O.D tool. The over shots are designated by a series number that indicates their application for fishing certain types of fish e.g. Series 70. Over shots are used to release a fish with short space to engage the tool on it. Similarly, Series150 over shots are used to release fish with sufficient neck length and allow for circulation too. Description of Tool

The basic overshot (from top down) consists of a top sub, a bowl, grapple, control and a guide. In addition to the basic components, some over shots can be dressed with either: 

Spiral Grapple – used if the fish diameter is near the maximum catch of the overshot.



Basket Grapple – used if the fish diameter is considerably below maximum catch size (usually ½”)

Some times over shots are used with extension subs that are installed between the top sub and the bowl of the overshot and extends the overshot bowl. Extension subs are used to either establish a longer hold on a fish that may be undersize at the top by having been pulled in two/ an overshot released several times or cover a bad section of pipe so that a tool joint can be


Page | 20

Summer Training Report caught. Extension subs will only cover a fish O.D. equal to the maximum catch of the overshot using a basket grapple and still remain full strength. ii.

Die Collar

The Die Collar is designed to retrieve tubular members from the well bore. The Die Collar is manufactured from high-grade alloy and specially heat-treated. The hardened cutting teeth (wickers) are machined on a shallow taper (approximately 3/4 inch per foot) to provide an excellent grip and positive engagement. For operation, the tool is run to the fish top and minimum weight and sufficient rotation is applied to allow the wicker threads to become embedded in the exterior surface of the fish. A major disadvantage of die collar is that the dis-engagement of die collar, in case the stuckup is not released, is extremely difficult and may further complicate the fishing operations.

B. Internal Catch Tools The internal catch tools engage a fish on its inside body. Some of the commonly used internal catches fishing tools are: i.

Taper Tap

The Taper Tap operates in an exactly opposite manner to a die collar and is basically designed to retrieve tubular members from the well bore. It is the most economical tool of its kind for freeing fish. The Taper Tap is also manufactured from high-grade alloy and specially heattreated. The basic Taper Tap is a single piece construction. The hardened cutting teeth (wickers) are carbo-nitrided and machined on a shallow taper (approximately 3/4 inch per foot) to provide an excellent grip for light duty pick-up jobs. For operation, the taper tap is run to the top of fish and rotated sufficiently to allow the wicker threads to get embedded into the interior surface of the fish. ii.

Grapple Releasing Spears

The grapple releasing spears are rugged, dependable and inexpensive tools used to retrieve casings for side tracking purposes or tubing left due to free fall. The simple design assures positive engagement throughout the fishing operation, is easy to release and re-engage if necessary and may be run in conjunction with other equipment such as pack-off attachments and internal cutting tools. The basic tool consists of a mandrel, a grapple, a bull nose nut and a release ring. C. Junk Catcher Tools


Page | 21

Summer Training Report The junk catcher tools are used to remove junk/ debris from the well bore prior to/during fishing/milling operations. Some of the commonly used such tools are: i.

Jet Basket

Jet basket is used to recover small objects such as bit cones, bearings, mill cuttings, broken slips, hand tools and fragments of steel. Objects are forced into the basket by high-pressure jets forcing fluid down the outside of the tool. The fluid exits through the tool I.D. moving the object into the basket allowing the spring loaded catch fin gers to catch the object. The jet basket is usually made up in the fishing string below the drill collars in place of the bit. The basket is lowered into the hole to a few feet off bottom and full circulation started while slowly rotating the string to flush the hole of cuttings. ii.

Junk Basket

The junk basket is a highly successful fishing tool that incorporates a mill with double sets of free finger type catchers. It will catch most small objects that may be dropped into the hole including irregular objects. It is used to catch bit cones, slip fragments, wire line, hand tools and other similar objects. Additional uses are to take core samples, drill full gauge holes or ream. The manganese bronze catching fingers can be field dressed. iii.

Reverse Circulating Junk Basket

The conventional junk catchers employ forward/direct circulation at the bottom to lift the cuttings and trap them. The distance to which the junk is to be lifted is normally more and hence such tools are less effective. In the Reverse Circulating Junk Basket also forward circulation is applied in the string that gets converted to reverse circulation at the tool due to a ball. The RCJB is a better junk catcher tool since the junk needs to travel a shirt distance only before it gets trapped in the catcher sub. RCJB is used to remove objects such as slips, hand tools, bit cones and any other small pieces of junk from bottom of well bore.

D. Accessory Tools Various accessories are used in the fishing string. Some of them are: i.

Wire Catcher / Wire Line Spear

The wire line catcher is used to retrieve wire line.

ii.

Fishing Magnet


Page | 22

Summer Training Report The fishing magnet is used to retrieve all types of small objects having magnetic attraction from the borehole bottom. Objects such as bit cones, bearings, slips, tong pins and mill cuttings can often be retrieved only by magnetic attraction. iii.

Lead Impression Block (Lib)

The LIB is used to determine the configuration of fish top and to locate its position in the well bore. The impression block is lowered on the end of the fishing string to approximately 5 feet above the fish. Circulation is used to clean the top of the fish and the string is then rapidly slacked and set on fish with 15,000 to 20,000 pounds of weight on the fish to get a good impression of fish top. iv.

Hydraulic Fishing Jar

The hydraulic fishing jar is used when a powerful upward blow is required to release the stuck fish. The hydraulic jar is placed directly below the drill collars in the fishing string. The intensity of each blow is controlled by the amount of stretch placed in the drill string. More the pull harder is the blow. The jarring effect is enhanced by placement of drill collars above the jar. v.

Bumper Sub

Bumper sub is used below hydraulic jar to prevent transmission of impact generated by jar to tubing.

F IGURE 10: SPIRAL GRAPPLE


Page | 23


F IGURE 11: SPEARHEAD

F IGURE 12: M ILLING TOOLS


Page | 24


3.3 Well Completion and Testing 3.3.1 Surface Equipments 3.3.1.1 

Well Head Equipments

Wellhead equipments are attached to the top of the tubular goods used in a well (API 6A)



o

To support the tubular string and hang them.

o

Seals between strings.

o

Control production from the well.

They are permanent facilities after drilling is finished and resist high pressure and do not leak being reliable and steady.



They should be corrosion resistant for wells producing H 2S and C02.

Lowermost casing head 

Lowermost Casing heads provide a secure connection between the surface casing and the blowout preventer during drilling, and support the next casing string in the bowl

Features and Benefits

The bowl provides a load area, which must be able to support the casing hanger (mandrel or slip type), the weight of the entire casing string, and the load from testing the wellhead connection if no test protector is used. 

Bottom connection - Slip-On-Weld and Buttress thread, with Base Plate are available.



Seal - The bowl provides a sealing area to isolate the annulus between the inside diameter of the bowl and the outside diameter of the casing. The casing hanger, or a separate seal assembly usually provides this seal.



Side outlets - Side outlets are available with line pipe thread and studded options. All outlets are prepared for valve removal plugs

Intermediate Casing Head/ casing spool 

It is a spool type unit or housing attached to the top flange of the underlying casing head.


Page | 25




It is composed of: 

A lower flange



One or two side outlet



An internal casing hanger bowl



A top flange where BOP or tubing head can be connected

Casing Hanger 

The casing hanger is a wrap-around, slip-type, weight-set hanger. It may be installed through the BOP and is suitable for heavy casing loads.



The hanger supports casing weight and seals the annulus before the BOP is removed. Weight is supported on a solid shoulder not on seal; therefore, it will not over-compress the seal.



The upper body diameter is larger to centralize and protect seals



The elastomer seal is mechanically activated by cap screws.

Casing Seal 

The casing seal consists of elastomer chevron rings that seal against casing.



The seal is energized by injecting sealant into pressure rings.



Metal backup rings prevent pressure extrusion during thermal cycling.

Tubing Head/ tubing spool 

Attached to the top flange of the uppermost casing head to provide a support for tubing string.



Seal annular space between the tubing string and production casing string.



It is composed of: 

A lower casing flange



One or two side outlets



Top flange with internal hanger bowl.



It has provision for anchor bolts to secure tubing hanger.

Tubing Hanger 

It is used to provide a seal between the tubing and the tubing head or to support the tubing and to seal between the tubing and tubing head.


Page | 26


3.3.2 Downhole equipments Packer

A packer provides a means of sealing the tubing string from the casing, thereby preventing communication of fluids.

F IGURE 13: TYPES OF PACKER

Expansion Joint 

Expansion joints are designed to be used in single and multiple stri ng completion when tubing is expected to change length because of temperature and/or pressure changes during treatment or production.



Expansion Joint is splined to provide rotational lock for the full travel expansion.



It can be pinned at different stroke lengths as per the requirement.



Higher temperatures can be achieved using alternate seal stacks.

Flow Coupling 

The Flow Couplings are heavy walled tubing pups that are installed above and below nipples and sliding sleeves,



Where it is anticipated to have internal erosion, caused by the abrasive action of turbulent flow through these restricted areas.





The Flow Couplings are available in 36 or 48 inch lengths. Flow Coupling is manufactured for Standard, H 2S and H2S-CO2 service


Page | 27

Summer Training Report Blast Joint 

Blast Joints are heavy walled tubing, run in the tubing string and positioned across from a perforated interval where the jetting action of the fluid can erode the outside of the tubing, thus prolonging the life of the completion.



A blast joint is also a length of tubing with enhanced wall thickness.

Landing Nipple 

Landing nipple in the tubing string enables the installation of various control equipment with wireline.



The landing nipple with their variety of profiles, allow the incorporation of an unlimited number in a tubing string, with complete selectivity for setting and locking of the appropriate mandrels.



The well may have atleast one landing nipple in the tubing string .It performs a dual functions 

It prevents the wireline tools larger than the no-go dimensions from being run below the tubing.



It permits re-cocking of hydraulic jars when tr ying to open or close sleeves.

Sliding Sleeve 

Sliding sleeves are part of tubing string and provide communication between the tubing and the annulus.



Used for following application



Displacing fluids



Selective testing treating and production in multiple completion



Killing by circulation.



Pressure equalising



Install valve, choke and flow regulator in the nipple profile provided.

Side pocket mandrel 

Side pocket mandrel has a polished receptacle/pocket a t one side which receives down hole tools lowered by wire line.



Side pocket mandrels can be positioned in the tubing string where it is necessary to install 

GLV



chemical injection valve


Page | 28

Summer Training Report 

Hot oil injection valve



Chemical injection valve



Test or treat selectively



Provide communication between the tubing and annulus when required.

Pump Out Plug 

A pump out plug is generally run at the bottom of the string and is used for hydraulically setting the packer.



It has a seat to accommodate the ball & the seat is locked in position by shear screws of specified shear value.



The ball dropped for setting the packer seats on the seat & ensure leak proof system.



After setting the packer, further pressurizing shears the shear screws the seat & ball drops in to the sump.

Wire line re-entry guide 

The wire line re-entry guide forms the bottom most part of the completion string and is basically a mule shoe that is beveled to facilitate easy lowering & pulling of wire line string through it.

Bridge Plug 

A bridge plug is set in the casing to prevent the flow across that point in the casing.



It provides additional safety while the X-mas tree is being nippled up or nippled down.



It may be permanent or retrievable.



Bridge plug can also be set between perforations to isolate the lower perforation while the upper zone is squeezed cement, acidised or fractured.



They can be set either mechanically or by wireline.

Cement Retainer 

The tool utilizes a production packing element design for effective sealing in the well bore. During run-in, the packing element traps atmospheric pressure between itself and the body.



As hydrostatic pressures increase, the tighter the element hugs the body, resulting in higher run-in speeds without fear of swabbing.



Both the upper and lower slips are locked in position for safe tripping in bore.

the well

When the slips are set in the casing, they encompass nearly the entire

circumference of the casing for maximum anchoring ability.


Page | 29




The retainer can be set by electric-line or mechanically.



Incorporated in the body design is a snap-in, snap-out buttress thread profile, resulting in a low snap-in force.

Casing Scraper 

A casing scrapper is used to remove foreign substances, such as scale, perforating burs and cement from inside the casing wall.



The scrapper is usually run above a bit and reciprocated in the casing.



The scrapping action is provided by spring tensioned blade against the casing wall.

F IGURE 14: HYDRAULIC PACKER

F IGURE 15: SLIDING SLEEVE

3.4 Well Stimulation Services Intially or during the producing life of a well it may not produce as expected or may go off production for many reasons. Well stimulation techniques are tools for improving or restoring


Page | 30

Summer Training Report productivity. WSS came into being its present entity in 1983-84 to fulfil the need of stimulation and specialized services for enhancing oil and gas production. WSS provides services in following areas: 

Acidization



Hydraulic fracturing



Specialized services  

Coil tubing services Nitrogen services



Sand control by gravel pack



Water shut off



Hot oil services

3.4.1 Coiled tubing unit Coiled tubing is a well intervention method to deploy tools and equipments into a well.

F IGURE 16: COILED TUBING UNIT

Parts of Coiled Tubing Unit: 

Tubing reel: In tubing reel, the coil tubing is spooled or stored.


Page | 31




Tubing Guiding Arch and Tubing Injector: Tubing guiding arch guides the coil tubing from service reel to the injector chain present in the injector head. Tubing injector controls the rate of lowering the tubing into the well under various well conditions. It supports full weight of the tubing.



Stripper: Between BOP and injector head provides the primar y operational seal between pressurized wellbore fluids and the surface environments. It provides both static and dynamic seal.



BOP: BOP of coil tubing unit is a quad ram BOP. It contains all the four rams- blind ram, shear ram, slip ram and pipe ram.

3.4.2 Operations Performed By WSS Section 3.4.2.1 Dewaxing by Hot Oil Circulation Using Coiled Tubing Unit

The oil producing from the well was waxy crude oil. As the oil flows up the tubing, the temperature decreases and wax started to deposit in the well bore. These gradually reduced the inside diameter of the tubing and finally blocked the tubing. To resume production from the wellbore first scrapping operation was conducted in the wellbore but when it was not so effective, it was decided to perform hot oil circulation operation to melt the wax in the wellbore. Coiled tubing was run into the well inside the tubing and the other end was connected to the tanker where oil was heated to nearly 80 oF. Through the coiled tubing hot oil was circulated. As soon as the wax was melted, oil from the bottom hole started to flow to the surface. 3.4.2.2 Nitrogen Pumping Through Coiled Tubing Unit

Nitrogen pumping unit is taken to the site that contains two parts: a tank that contains liquid nitrogen and a compressor unit. Coiled tubing is lowered into the well and using connections nitrogen is pumped inside the tubing. Before injecting liquid nitrogen is converted to vapour state and it is injected by using the compressor. The purpose of nitrogen pumping is activation i.e. in order to remove the water head in the tubing to all ow the flow from the formation.


Page | 32


4 Crisis Management 4.1 Kick A Kick is defined as an undesirable influx of formation fluid into the borehole. If left unattended a kick can develop into a blowout (an uncontrolled influx of formation fluid into the borehole). While kicks are a problem, they are not too common. However, the penalty for failing to control a kick can be the loss of the well, and quite possibly the loss of the rig and the lives of the crew. Well control procedures vary slightly from the rig to rig, and company to company, but four simultaneous operations are normally considered. T ABLE 3: K ICK CONTROL

Rig Control

This includes the BOP's, pumps, draw works and other rig equipment. This is the responsibility of the driller, and any blowout control procedures should assign these operations to the driller.

Mud Control

This involves the addition of weighting material (most commonly barite) to the mud to increase its density, but also includes the correct operation of the mixing system and chemical additions. These are generally the responsibility of the mud engineer and derrickman.

Choke Control

This includes the correct calculation of pressures and time relationships, as well as operating the choke and monitoring the pump rate. The choke operator should be the best trained man on the rig in kick control. He will be required to give guidance during the kill operations.

Supervision

This is the final element of control. This task will normally be assigned to the rig superintendent or toolpusher. They will supervise the previous three elements of well control operations.


Page | 33


4.1.1 Causes of Kicks There are 4 major reasons why kicks occur: 

Failure to keep the hole full



Swabbing of Formation Fluids into the Borehole



Insufficient Mud Density



Lost Circulation

4.2 Well Control Methods Basically there are four methods of well control: 1. The Driller’s method (recommended when the Wait and Weight method cannot be used for practical reasons). 2. The Wait and Weight method (recommended in most cases). 3. The Concurrent method (now an obsolete method). 4. The Volumetric method (required in special situation).

4.3 Blowout Prevention Equipments The Blowout Prevention (BOP) equipment is the equipment which is used to shut-in a well and circulates out an influx if it occurs. The main components of this equipment are the Blowout Preventers or BOP’s. These are valves which can be used to close off the well at surface. In addition to the BOP’s, the BOP equipment refers to the auxiliary equipment required to control the flow of the formation fluids and circulate the kick out safely. There are 2 basic types of BOP used for closing in a well: a) Annular (bag type) b) Ram type It is very rare for only one BOP to be used on a well. Two, three or more preventers are generally stacked up, one on top of other to make up a BOP stack. This provides greater safety and flexibility in the well control operation. a) Annular Preventers

The main component of the annular BOP is a high tensile strength, circular rubber packing unit. The rubber is mounted around a series a metal ribs. The packing unit can be compressed inwards against drillpipe by a piston, operated by hydraulic power.


Page | 34

Summer Training Report The advantage of such a well control device is that the packing element will close of around any size or shape of pipe. An annular preventer will also allow pipe to be stripped in (run into the well while containing annulus pressure) and out and rotated, although its service life is much reduced by these operations. b) Ram Type Preventers

Ram type preventers derive their name from the twin ram elements which make up their closing mechanism. Three types of ram preventers are available: i.

Blind rams – which completely close off the wellbore when there is no pipe in the hole.

ii.

Pipe rams – which seals off around a specific size of pipe thus sealing off the annulus.

iii.

Shear rams – which are the same as blind rams except that they can cut through drillpipe for emergency shut-in but should only be used as a last resort. A set of pipe rams may be installed below the shear rams to support the severed drillstring.

F IGURE 17: A NNULAR BOP


Page | 35


Drilling Spools A drilling spool is a connector which allows choke and kill lines to be attached to the BOP stack. The spool must have a bore at least equal to the maximum bore of the uppermost casing spool. The spool must also be capable of withstanding the same pressures as the rest of the BOP stack.

Diverter System The diverter is a large, low pressure, annular preventer equipped with large bore discharge flowlines. This type of BOP is generally used when drilling at shallow depths below the conductor. If the well were to kick at this shallow depth, closing in and attempting to contain the downhole pressure would probably result in the formations below the conductor fracturing and cratering of the site or at least hydrocarbons coming to surface outside of the conductor string. The purpose of a diverter is to allow the well to flow to surface safely, where it can be expelled safely expelled through a pipeline leading away from the rig.

Choke and Kill Lines When circulating out a kick the heavy fluid is pumped down the drillstring, up the annulus and out to surface. Since the well is closed in at the annular preventer the wellbore fluid leave the annulus through the side outlet below the BOP rams or the drilling spool outlets and pass into a high pressure line known as the choke line. This choke line carries the mud and the influx from the BOP stack to the choke manifold. The kill line is a high pressure pipeline between the side outlet, opposite the choke line outlet, on the BOP stack and the mud pumps and provides a means of pumping fluids downhole when the normal method of circulating down the drillstring is not possible.

Choke Manifold The choke manifold is an arrangement of valves, pipelines and chokes designed to control the flow from the annulus of the well during a well killi ng operation. It must be capable of: a) Controlling pressures by using manually operated chokes or chokes operated from a remote location. b) Diverting flow to a burning pit, flare or mud pits, c) Having enough back up lines should any part of the manifold fail. d) A working pressure equal to the BOP stack.


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Hydraulic Power Package (Accumulators) The opening and closing of the BOP is controlled from the rig floor. The control panel is connected to an accumulator system which supplies the energy required to operate all the elements of the BOP stack. The accumulator consists of cylinders which store hydraulic oil at high pressure under a compressed inert gas (nitrogen). When the BOPs have to be closed the hydraulic oil is released (the system is designed to operate in less than 5 seconds). Hydraulic pumps replenish the accumulator with the same amount of fluid used to operate the preventers. Another function of the accumulator unit is to maintain constant pressure while the pipe is being stripped through the BOPs.


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5 Artificial Lift Artificial lift refers to the use of artificial means to increase the flow of liquids, such as crude oil or water, from a production well. Generally this is achieved by the use of a mechanical device inside the well (known as pump or velocity string) or by decreasing the weight of the hydrostatic column by injecting gas into the liquid some distance down the well. Artificial lift is needed in wells when there is insufficient pressur e in the reservoir to lift the produced fluids to the surface, but often used in naturally flowing wells (which do not technically need it) to increase the flow rate above what would flow naturally. The produced fluid can be oil, water or a mix of oil and water, typically mixed with some amount of gas. The types of artificial lift available are: 1) Gas lift -continuous gas lift -intermittent gas lift 2) Sucker rod pumping 3) Electrical submergible pumping 4) Progressive cavity pumping 5) Jet pumping There are various factors upon which a selection of artificial method depends. T ABLE 4: FACTORS FOR SELECTION OF ARTIFICIAL LIFT

Sucker rod

Gas lifting

pumping

Electrical submergible pumping

100’ -16000”

5000’-15000’

TVD

TVD

Operating volume

5-5000 BPD

200-30000 BPD

200-30000 BPD

Operating

100-550 0F

100-400 0F

100-400 0F

Fluid gravity

>80 API

>150API

>100 API

Offshore

Limited

Excellent

Excellent

Fair to good

Poor

Poor to fair

Operating depth

1000’-15000’TVD

temperature

application Solid handling


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Summer Training Report Overall system

45%-60%

10%-40%

35%-60%

efficiency

Most important factors for choice of lift modes:

For very high volume of production - GL, ESP or HP For very low volume of production - SRP or IGL For moderate volume of production - GL, ESP, HP or SRP For very deep well of production

- HP

5.1 Electrical Submersible Pump An artificial-lift system s ystem that utilizes a downhole pumping system that is electricall y driven. The pump typically comprises several staged centrifugal pump sections that can be specifically configured to suit the production and wellbore characteristics of a given application. Electrical submersible pump systems are a common artificial-lift method, providing flexibility over a range of sizes and output flow capacities. The Electric Submersible Pump System consists of several components that are carefully selected to combine into the most economical and efficient solution for each set of well conditions. 1. Surface Equipment 2. Power Cable 3. Motor Lead Extension 4. Pump: The pumping unit itself consists of the multi-stage centrifugal pump housed in a pressure sleeve with the capability of producing capacities up to 50.000 BPD from depths of up to 13.900 ft. 5. Gas Separator/Intake: Immediately under the pump is the intake combined with a gas separator if required. The gas separator allows for trouble free operation in well conditions with free gas contents of more than 10%.


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Summer Training Report 6. Motor: The high quality electrical motor (6) for well casings 41/2" and larger is a squirrel cage, two pole, three phase induction motor. The motor turns at a speed of approximately 3500 RPM at 60 Hz and 2900 RPM at 50 Hz power source. s ource. 7. Sensor: The down hole hole sensor is located below the motor and transmits im portant well and system data via the main power cable to the t he surface. 8. Protector: Located between motor and pump intake is the protector. The protector isolates the motor from the well fluid and contains the high capacity thrust bearing. 9. Check Valve & Drain Valve: Other protective devices are located above the pump discharge: The check valve that closes on shut down of the unit and prevents back spinning and the drain valve that allows all ows for pulling the ESP without a wet tubing string. Working Operation of ESP

F IGURE 18: ESP


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Summer Training Report Electric Submersible Pumping Systems incorporate an electric motor and centrifugal pump unit run on a production string and connected back to the surface control mechanism and transformer via an electric power cable. The downhole components are suspended from the production tubing above the wells' perforations. In most cases the motor is located on the bottom of the work string. Above the motor is the seal section, the intake or gas separator, separator, and the pump. The power cable is banded to the tubing and plugs into the top of the motor. motor. As the fluid comes into the well it must pass by the motor and into the pump. This fluid flow past

the motor aids in the cooling of the motor. The fluid then enters the i ntake and is taken

into the pump. Each stage (impeller/diffuser combination) adds pressure or head to the fluid at a given rate. The fluid will build up enough pressure as it reaches the top of the pump to lift it to the surface and into the separator or flowline. Electric s ubmersible pumps are normally used in high volume (over 1,000 BPD) applications.

5.2 Sucker Rod Pumping Introduction Sucker rod pumping is also als o referred to as ‘‘beam pumping.’’ pumping.’’ It provides mechanical energy to lift oil from bottom hole to surface. It is efficient, simple, and easy for field people to operate. It can pump a well down to very ver y low pressure to maximize oil production rate. It i s applicable to slim holes, multiple completions, and high-temperature and viscous oils. The system is also easy to change to other wells with minimum cost. The major disadvantages of beam pumping include excessive friction in crooked/ deviated holes, solid-sensitive problems, low efficiency in gassy wells, limited depth due to rod capacity, and bulky in offshore operations. Beam pumping trends include improved pump-off controllers, better gas separation, gas handling pumps, and optimization using surface and bottom-hole cards.

Pumping System A sucker rod pumping system consists of a pumping unit at surface and a plunger pump submerged in the production liquid in the well. The prime mover is either an electric motor or an internal combustion engine. The modern method is to supply each well with its own motor or engine. Electric motors are most desirable because they can easily easil y be automated. The power from the prime mover is transmitted to the input shaft of a gear reducer r educer by a V-belt drive. The output shaft of the gear reducer drives the crank arm at a lower speed (4–40 revolutions per minute [rpm] depending on well characteristics and fluid properties). The rotary motion of the crank arm is converted to an oscillatory oscillator y motion by means of the walking beam through a pitman


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Summer Training Report arm. The horse’s head and the hanger cable arrangement is used to ensure that the upward pull on the sucker rod string is vertical at all times (thus, no bending moment is applied to the stuffing box). The polished rod and stuffing box combine to maintain a good liquid seal at the surface and, thus, force fluid to flow into the ‘‘T’’ connection just below the stuffing box. Conventional pumping units are available in a wide range of sizes, with stroke lengths varying from 12 to almost 200 in. The strokes for any pumping unit type are available in increments (unit size). Within each unit size, the stroke length can be varied within limits (about six different lengths being possible). These different lengths are achieved by varying the position of the pitman arm Connection on the crank arm. Walking beam ratings are expressed in allowable polished rod loads (PRLs) and vary from

F IGURE 19: CONVENTIONAL SRP

approximately 3,000 to 35,000 lb. Counterbalance for conventional pumping units is accomplished by placing weights directly on the beam (in smaller units) or by attaching weights to the rotating crank arm (or a combination of the two methods for larger units). In more recent designs, the rotary counterbalance can be adjusted by shifting the position of the weight on the crank by a jackscrew or rack and pinion mechanism. There are two other major types of pumping units. These are the Lufkin Mark II and the AirBalanced Units. The pitman arm and horse’s head are in the same side of the walking beam in these two types of units (Class III lever system). Instead of using counter-weights in Lufkin Mark II type units, air cylinders are used in the air balanced units to balance the torque on the crankshaft.


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The American Petroleum Institute (API) has established designations for sucker rod pumping units using a string of characters containing four fields. For example, C---228D---213---120

The first field is the code for type of pumping unit. C is for conventional units, A is for air balanced units, B is for beam counterbalance units, and M is for Mark II units. The second field is the code for peak torque rating in thousands of inch-pounds and gear reducer. D stands for double-reduction gear reducer. The third field is the code for PRL rating in hundreds of pounds. The last field is the code for stroke length in inches.

F IGURE 20: LUFKIN MARK II UNIT

SRP Installation


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STRUCTURE

HORSE HEAD MOTER

SAMPSON

SKID

SKID

POST

CRANKSHAFT

HOOK UP WITH POLISHED ROD

COUNTER WEIGHT

F IGURE 21: SRP INSTALLATION SEQUENCE

F IGURE 22: WALKING BEAM AND SAMSON POST


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F IGURE 23: C OUNTERWEIGHTS

F IGURE 24: C RANKSHAFT


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F IGURE 25: SPECIFICATION OF SRP IN FIELD

F IGURE 26: HORSEHEAD AND BRIDLE


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5.3 Gas Lift Gas Lift Classification

Broadly the Gas Lift operation can be classified into two types depending upon their mode of operation. 1. Continuous Gas Lift 2. Intermittent Gas Lift Continuous Gas Lift

In continuous flow operations a continuous volume of high pressure is injected through the educator tube to lighten or aerate a column of fluid which allows sufficient pressure differential across the sand face causing the well to produce at a desired rate of flow. To obtain this a flow valve is used which allows the deepest one point injection of the available Gas Pressure in conjunction with a valve that acts as a variable valve with a changing orifice which controls the rate of Gas Injection at the surface. Continuous Lift can be used in wells exhibiting the following characteristics: 

Wells with a high PI



Wells having a reasonably high bottom hole pressure (BHP)

Intermittent Gas Lift

Intermittent Flow involves the expansion of a high pressure gas ascending to a low pressure outlet. A valve provides complete volume and pressure expansion control of the gas entering into the tubing thus either regulating the lift of the column of fluid above the valve position with maximum velocity to minimize fluid slippage or controlling liquid fall-back and also delivering fluid to the outlet tank with minimum gas. It is used in conjunction with a surface time cycle controller or an intermitter. Intermittent Gas Lift can be applied to wells having the following characteristics: 1. High PI with low bottom hole pressure. 2. Low PI with low bottom hole pressure . In intermittent Gas Lift, gas is injected at regular intervals into the casing annulus by using an intermitter. Intermitter is a motor valve operated with a connecting timing device which allows selective cycling and controlled gas injection into the casing annulus.


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Summer Training Report However there are installations in which intermittent gas lift is obtained without the use of a surface intermitter. These types of installations require a valve that is somewhat more fluid sensitive than normal and requires a built in spread. Use of this type of valves may present problems where fluid must be lifted overlong flow-lines against surface chokes and in situation where sensitivity of the valves may become a disadvantage. Intermittent Gas Lift can also be accomplished using multi-point injection of gas using multiple Gas Lift Valves. This type of installation must be designed such that the lowest Gas Lift Valves open just as the slug passes each valve. Injection Rates

In independent studies conducted by investigators on Gas Lift efficiency, 4 types of Gas Injection Rates were found which were significant in any Gas Lift installations. These were as following: 

Injection Rates for no flow at extremely low injection rates. If the gas is injected at extremely low rate, it rises to the surface in form of small hemispheres flat at the bottom.



Injection Rate of Maximum efficiency where minimum volume of gas is required to loft 1 barrel of oil.



Injection Rate of maximum production. This the volume of gas required for maximum production.



Injection Rate of no flow due to excess Gas Injection, which is reached when the friction produced by the gas prevents the Liquid from entering the tubing

5.4 Hydraulic Pumping Hydraulic Pumping systems consist of the following a) Surface Power Fluid system b) Prime Mover c) Surface Pump d) Downhole Jet or Reciprocating Pump In hydraulic pumping system, a hydraulic engine-pump assembly is attached at the bottom of the production tubing. The unit is installed in the well below the working fluid level. A high pressure power fluid, liquid oil whose pressure is build up by a surface pump, is pumped down


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Summer Training Report to the engine from the surface. The power fluid drives the hydraulic engine which in turn operates the subsurface pump.

5.5 Jet Pumping In a jet pump, the power fluid enters the top of the pump from the tubing and passes through the nozzle where virtually all of the total pressure of the power fluid is converted to a velocity head. The jet from the nozzle discharges into the production inlet chamber which is connected to the formation. When the pressure becomes lower than the formation pressure, fl uid is drawn in from the well bore. The combined production fluid & power fluid then enters the throat of the pump. In the confines of the throat, which is always of large diameter than the nozzle, complete mixing of the power fluid and production fluids takes place. During this process, the power fluid losses momentum and energy, and the production fluid gains momentum and energy. The resultant mixed fluid exiting the throat having sufficient velocity head, enters the diffuser section of the jet pump. The expanding area of the diffuser section converts the velocity head of the mixed fluid to pressure head greater than the liquid column head, allowing flow to the surface.


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F IGURE 27: JET PUMP

5.6 Progressive Cavity Pumping The progressive cavity pump (PCP) is a positive displacement pump, using an eccentrically rotating single- helical rotor, turning inside a stator. The rotor is usually constructed of a highstrength steel rod, typically double-chrome plated. The stator is a resilient elastomer in a double-helical configuration moulded inside a steel casing. Progressive cavity pumping systems can be used for lifting heavy oils at a variable flow rate. Solids and free gas production present minimal problems. They can be installed in deviated and horizontal wells. With its ability to move large volumes of water, the progressing cavity pump is also used for coal bed methane, dewatering, and water source wells. The PCP reduces overall operating costs by increasing operating efficiency while reducing energy requirements.


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F IGURE 28: PCP COMPONENTS


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5.7 Artificial Lift - Comparison

TABLE 5: SELECTION CRITERIA FOR VARIOUS ARTIFICIAL LIFT TECHNIQUES


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Project Report_ Summer Training@Ankleshwar, ONGC

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