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Page 1: Drill Stem Testing.

DRILL STEM TESTING

DRILLING PRACTICES

Page 2: Drill Stem Testing.

DRILL STEM TESTING

A TEMPORARY WELL COMPLETION TO GATHER INFORMATION ON THE POTENTIAL PRODUCTIVITY OF A FORMATION.

WHAT IS A DRILL STEM TEST

WHO REVIEWS THE DST PROGRAM

OIM SENIOR TOOLPUSHER OPERATOR REP KEY SERVICE PERSONNEL

KEY AREA’S OF REVIEW

COMMUNICATION ROLES AND RESPONSIBILITIES EMERGENCY RESPONSE

EXPECTED TEST PARAMETERS

• Temperature

• Pressure

• Hazards

REQUIRED CHANGES TO PROGRAM

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BASIC PRECAUTIONS

• PRIOR TO CONDUCTING ANY DST THE BOP’S AND GAS DETECTION SYSTEM WILL BE TESTED.

• DRILLPIPE OR TUBING CAN BE USED BUT MUST BE DESIGNED FOR ANTICIPATED CONDITIONS. ANY DOUBT ABOUT THE TEST STRINGS INTEGRITY WILL BE REFERED TO THE RIG MANAGER.

• DURING THE TEST THE ANNULUS PRESSURE WILL BE MONITORED TO ENSURE A LEAK DOES NOT DEVELOP IN THE TEST STRING.

• ALL DST WORK WILL USE A SURFACE TREE THAT ENABLES THE TEST STING TO BE CLOSED IN.

• WHEN WIRELINE IS TO BE USED DURING THE TEST A LUBRICATOR WILL BE INSTALLED ON SURFACE STACKS.

• WHEN A DST IS FINISHED, CONTENTS OF TEST STRING ARE REVERSE CIRCULATED OUT PRIOR TO RELEASE OF PACKER OR UNSTINGING FROM PERMANENT SET PACKER.

• SPECIAL ATTENTION SHOULD BE EMPHASISED FOR H2S DETECTION.

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SPECIAL PRECAUTIONS FOR FLOATERS

• TEST STRING HUNG OFF IN BOP’S WITH A SUBSEA MASTER VALVE INSTALLED (E-Z TREE OR SUBSEA TEST TREE).

• ENSURE TIME IS KNOWN FOR UNLATCHING IN EVENT OF AN EMERGENCY.

• TEMPORARY ABANDONMENT THE BLIND RAMS WILL BE CLOSED ABOVE THE MASTER VALVE.

• ENSURE ENOUGH HIGH PRESSURE FLEXIBLE LINES ARE USED TO COMPENSATE FOR MAX HEAVE.

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PRECAUTIONS WHILE TESTING

• FOR INITIAL TEST OF A ZONE, DST TOOLS MUST NOT BE OPENED AT NIGHT WITHOUT THE PERMISSION OF THE OPERATIONS MANAGER. THE REGION MANAGER MAY DECIDE THAT THIS DECISION WILL BE MADE AT REGIONAL LEVEL.

• WHEN TEST WELLS CONTAINING H2S NO GAS SHOULD BE RELEASED INTO THE ATMOSPHERE

UNLESS IT IS BURNED ON THE SPOT.

• ALWAYS OPEN UP A WELL SLOWLY, USING THE UPPER MASTER VALVE.

• AN EMERGENCY SURFACE SHUT-DOWN SYSTEM (ESD) SHOULD BE INCORPERATED INTO ANY WELL TEST HOOK UP.

• ALWAYS PRESSURE TEST THE INSTALLED EQUIPMENT, PRIOR TO OPENING UP THE WELL.

• SPACING OF UNITS INVOLVED IN WELL TEST HOOK-UP SHOULD BE AS PER RECOMMENDED SAFETY STANDARDS.

• WIND DIRECTION OR NO WIND NEEDS TO BE CONSIDERED.

• MINIMISE RISKS WITH IGINTION SOURCES BY GROUNDING UNITS, NO NAKED FLAMES ETC.

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REASONS TO DO A DRILL STEM TEST

WE NEED TO KNOW :

• IF THERE IS A RESERVOIR

• WHAT DOES IT CONTAIN

• AT WHAT RATE WILL IT PRODUCE

• FOR HOW LONG

• WHAT FACILITIES WILL BE REQUIRED AND WHEN

• WHAT HAZARDS ARE THERE

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KNOWLEDGE+

RISK

LOW

HIGH

KNOWLEDGE vs RISK

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Data Source Possible Analysis

Seismic Identify possible Accumulations

Regional Information Qualitative Accumulation size and shape using assumed

Velocity Profile

Hydrocarbon Prospectivity (Seismic oddities / regional information)

Degree Of Development Uncertainty = Very High

PRE-DRILLING PHASE

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Data Source Possible Analysis

Mud Log Lithology Hydrocarbon Shows Geological ProfileCore Samples Depositional EnvironmentMWD Logs Qualitative Hydrocarbons

Pressure Regime (Qualitative) Formation Characteristics at the wellboreFluid ContactsNear-wellbore petrophysical parameters

Degree Of Development Uncertainty = High

DRILLING A WELL

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Data Source Possible Analysis

Well Logs Near-well formation characteristics VSP Hydrocarbon ContactsRFT Samples Lithology

Qualitative HC mobility Qualitative presence of hydrocarbons (HC)

Confirm Seismic velocity profileFirm-up structure mappingQuantitative Pressure regimeQualitative HC PVT analysis

Degree Of Development Uncertainty = High

OPEN HOLE LOGGING

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Data Source Possible Analysis

Transient Pressure Response Near-well formation characteristics

Samples Near-Well Productivity Index

Additional qualitative PVT analysis

Degree Of Development Uncertainty = High

LIMITED INFLUX TESTING

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Data Source Possible Analysis

Transient pressure response Bulk reservoir propertiesPseudo Steady State Response Near-well boundaries Bulk HC Samples Ideal Productivity Index

Extended HC PVT AnalysisTrace Element analysis (qualitative)Processing characteristics of the HCFormation Integrity (sanding

tendency under high drawdown)

Degree Of Development Uncertainty = Medium

CONVENTIONAL WELL TESTING

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Data Source Possible Analysis

Steady State Pressure Response Establish Reservoir extent Surface Process Monitoring Pressure support mechanisms Wellsite Chemistry Development Strategy

Optimise Process Facility designMeasure Completion PerformanceCalibrate design programs, etc.Stabilised trace element analysis

Degree Of Development Uncertainty = Medium / Low

EXTENDED WELL TESTING

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Test programs

Planning and preparation• For conventional wells, 2 - 3 months from expected TD• For unconventional operations ( HPHT, EWT etc.), 6 - 12 months

Testing operations start once the the well has its final casing/liner string in place and final logs have been run.

TIMING

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Drilling vs Testing

– During conventional drilling, the mud weight is adjusted such that the hydrostatic pressure of the fluid counteracts the reservoir pressure

• Overbalanced situation, zero hydrocarbon flow to surface.

– During conventional testing, the fluid positioned above the reservoir creates a hydrostatic pressure which is less than the reservoir pressure.

• Underbalanced situation, reservoir fluids can now flow to surface

TESTING OPERATION

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• Function of DST tools

– Isolation of producing interval from mud hydrostatic

– Test “Cushion” - lighter fluid than mud hydrostatic fluid column

– Down hole shut-in valve to minimise wellbore storage

– Reverse valves to “kill” the well at the end of the test

– Slip joints to compensate for tubing length changes due to

temperature & pressure changes

DRILL STEM TEST TOOLS

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PERFORATING GUNS

PACKER

SAFETY JOINT / JAR

MEMORY GAUGES

DOWNHOLE SHUT IN VALVE

DRILL COLLARS

PRIMARY REVERSE VALVE

DRILL COLLARS

DRILL COLLARS

SECONDARY REVERSE VALVE

SLIP JOINT, CLOSED

SLIP JOINT, FULLY OPEN

SLIP JOINT, 1/2 OPEN

RA SUB

DST TOOLS

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• Operating methods

– Tools are operated by

• String manipulation / rotation• Applied pressure to the annulus• Annular pressure• Tubing pressure

– Below packer and inside tubing - hydrocarbons– Above packer in casing tubing annulus - kill weight fluid

+ any applied pressure

DST TOOLS

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• Function of Sub Sea Landing String

– On a semi-sub or drill ship the test string requires additional components for safety & operational reasons.

• Sub Sea Test Tree, Retainer Valve– Provides the ability to isolate the tubing in the stack and

disconnect without killing the well.

• Lubricator Valve– Provides the ability to run extended length tool strings

without long sections of lubricator riser at surface.

SUBSEA SYSTEMS

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TEST TREE

FLUTED HANGER

SLICK JOINT

VALVE ASSEMBLY

LATCH ASSEMBLY

SUBSEA TEST TREE & VALVE ASSEMBLY

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COMPONENTS OF THE LANDING STRING

LATCHED UNLATCHED

SURFACE TREE

SWIVEL

LANDING STRING

SLICK JOINT

FLUTED HANGER

SPACER SUB

SUBSEA TEST TREE

SUBSEA TEST TREE LATCH ASSEMBLY

RETAINER VALVE

HOSE PROTECTOR

LUBRICATOR VALVE

HYDRAULIC HOSE REEL

CONTROL CONSOLE

RETAINER VALVE CLOSED

SUBSEA TEST TREE UNLATCHED

RAMS CLOSED

SUBSEA TEST TREE VALVES

CLOSED

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• Function of Well Test Equipment

– Management of pressure reduction from well to disposal system

– Heating if required of produced fluids

– Removal of any produced solids

– Separation of produced Oil, Water & Gas

– Disposal of produced fluid

– Data acquisition, flow rates, pressures & fluid samples

WELL TEST EQUIPMENT

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GENERAL LAYOUT OF WELL TEST EQUIPMENT

Courtesy of Expro Group

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• Function

– Primary pressure drop , flow control– Consists of an “adjustable” and a “fixed”

choke – Size of choke is usually given in 64ths of

an inch, equivalent bore– Adjustables used for clean-up period– Fixed used once pressure has stabilised

DIRECTION OF FLOW

ADJUSTABLE CHOKE TIP

CHOKE MANIFOLD

Adjustable choke

Fixed choke

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• Function

– To increase the temperature of the produced fluid downstream of the choke manifold

• Improved separation efficiency

– To provide a choke in a heated environment• Avoidance of hydrate formation

HEATER

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HEATER

WELL FLUID INLET

WELL FLUID OUTLET

STEAM INLET

BYPASS

STEAM OUTLET

SAFETY VALVE

DRAIN

CHOKE

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• Function

– Separation of produced oil, water & gas

– Rate measurement of produced fluid

– Provision of sampling points for re-combination samples

SEPARATOR

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HORIZONTAL SEPARATOR

Horizontal Separators

Primarily used for high liquid content wellsCourtesy of Expro Group

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Vertical Separators

Primarily used for high gas content wells Courtesy of Expro Group

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OIL BURNER

Courtesy of Expro Group

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Outline procedure

• Run scrapers across packer setting depth• Condition drilling mud or displace to brine • Run junk basket• BOP test• Space out run for sub-sea tree

Courtesy of Expro Group

PREPARATION

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TOOLS & SUB-SEA EQUIPMENT PREP

• Outline procedure

– Layout tools– Function and pressure test– Drift tools– Strap lengths of tools– Strap lengths of tubulars– Drift tubulars– Prepare running “tally”

ROTARY TABLE (RKB)

LAND-OFF POINT IN WELLHEAD

RESERVOIR FEATURE OR RA TAG

RA SUB IN TEST STRING

DISTANCE FROM RA SUB TO TOPSHOT

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SURFACE WELL TEST EQUIPMENT PREP

• Outline procedure

– Position equipment on rig deck

– Connect equipment using service pipe work

– Prepare instrument control and data acquisition equipment

– Pressure & function test equipment

– Function test safety system

– Prepare sampling equipment

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RUNNING PROCEDURES

• Typical Procedures on a Semi-sub

– Pick up and run TCP guns and DST tools• Check strap length between top shot and RA tag• Pressure test BHA

– Run tubing• Pressure test tubing

– Perform space out / correlation– Pull back to sub-sea hang off point– Run subsea equipment– Pick up and make up flowhead

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RUNNING PROCEDURES

• Typical procedures on a semi-sub

– Set packer

– Correlation run to confirm packer setting depth

– Pressure test landing string tools and surface tree & choke

– Function open tester valve and prepare to perforate well

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TEST PROGRAM

• Test program determined by test objectives

• Typical test program– Perforate - minimal flow– Down hole shut in to determine initial reservoir pressure– Clean-up flow– Initial build up– Single rate or multi rate flow period(s)– Main shut-in

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TESTING PROGRAM

• Typical test program

– Sampling flow period

– Well kill

– Pull test string

– Validate gauge data

– Abandon well