Drill Stem Testing.

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DRILLING PRACTICESDRILL STEM TESTING

DRILL STEM TESTINGWHAT IS A DRILL STEM TESTA TEMPORARY WELL COMPLETION TO GATHER INFORMATION ON THE POTENTIAL PRODUCTIVITY OF A FORMATION.

WHO REVIEWS THE DST PROGRAMOIM SENIOR TOOLPUSHER OPERATOR REP KEY SERVICE PERSONNEL

KEY AREAS OF REVIEWCOMMUNICATION ROLES AND RESPONSIBILITIES EMERGENCY RESPONSE

EXPECTED TEST PARAMETERS Temperature Pressure Hazards

REQUIRED CHANGES TO PROGRAM

BASIC PRECAUTIONS PRIOR TO CONDUCTING ANY DST THE BOPS 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.

SPECIAL PRECAUTIONS FOR FLOATERS TEST STRING HUNG OFF IN BOPS 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.

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.

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

KNOWLEDGE vs RISKHIGH

RISK

LOW

+ KNOWLEDGE

PRE-DRILLING PHASEData Source Possible AnalysisSeismic Identify possible Accumulations Regional Information Qualitative Accumulation size and shape using assumed Velocity Profile Hydrocarbon Prospectivity

(Seismic oddities / regionalinformation)

DRILLING A WELLData SourceMud Log Hydrocarbon Shows Core Samples MWD Logs

Possible AnalysisLithology Geological Profile Depositional Environment Qualitative Hydrocarbons Pressure Regime (Qualitative) Formation Characteristics at the wellbore Fluid Contacts Near-wellbore petrophysical parameters

Degree Of Development Uncertainty = High

OPEN HOLE LOGGINGData SourceWell Logs VSP RFT Samples

Possible AnalysisNear-well formation characteristics Hydrocarbon Contacts Lithology Qualitative HC mobility Qualitative presence of hydrocarbons (HC) Confirm Seismic velocity profile Firm-up structure mapping Quantitative Pressure regime Qualitative HC PVT analysis

Degree Of Development Uncertainty = High

LIMITED INFLUX TESTING

Data Source

Possible Analysis

Transient Pressure Response Samples

Near-well formation characteristics Near-Well Productivity Index Additional qualitative PVT analysis

Degree Of Development Uncertainty = High

CONVENTIONAL WELL TESTINGData Source Transient pressure response Pseudo Steady State Response Bulk HC Samples Possible Analysis Bulk reservoir properties Near-well boundaries Ideal Productivity Index Extended HC PVT Analysis Trace Element analysis (qualitative) Processing characteristics of the HC Formation Integrity (sanding tendency under high drawdown)

Degree Of Development Uncertainty = Medium

EXTENDED WELL TESTINGData Source Steady State Pressure Response Surface Process Monitoring Chemistry Possible Analysis Establish Reservoir extent Pressure support mechanisms Wellsite Development Strategy Optimise Process Facility design Measure Completion Performance Calibrate design programs, etc. Stabilised trace element analysis

Degree Of Development Uncertainty = Medium / Low

TIMING Test programsPlanning 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.

TESTING OPERATIONDrilling 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

DRILL STEM TEST TOOLS 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

DST TOOLSDRILL COLLARS

SLIP JOINT, FULLY OPENDOWNHOLE SHUT IN VALVE SLIP JOINT, 1/2 OPEN

MEMORY GAUGES

SLIP JOINT, CLOSED RA SUB DRILL COLLARS

SAFETY JOINT / JAR

PACKER

SECONDARY REVERSE VALVE

PERFORATING GUNS

DRILL COLLARS PRIMARY REVERSE VALVE

DST TOOLS 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

SUBSEA SYSTEMS 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 TEST TREE & VALVE ASSEMBLY

LATCH ASSEMBLY

VALVE ASSEMBLY

SLICK JOINT

FLUTED HANGER TEST TREE

SURFACE TREE

COMPONENTS OF THE LANDING STRINGCONTROL CONSOLE HYDRAULIC HOSE REEL RETAINER VALVE CLOSED

SWIVEL

LANDING STRING

LUBRICATOR VALVE HOSE PROTECTOR

SUBSEA TEST TREE UNLATCHED

RETAINER VALVE

RAMS CLOSED

SUBSEA TEST TREE LATCH ASSEMBLY SUBSEA TEST TREE

SUBSEA TEST TREE VALVES CLOSED

SLICK JOINT

SPACER SUB FLUTED HANGER

LATCHED

UNLATCHED

WELL TEST EQUIPMENT 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

GENERAL LAYOUT OF WELL TEST EQUIPMENT

Courtesy of Expro Group

CHOKE MANIFOLD 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 stabilisedADJUSTABLE CHOKE TIP

DIRECTION OF FLOW

Adjustable choke

Fixed choke

HEATER

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

STEAM INLET WELL FLUID INLET

STEAM OUTLET

SAFETY VALVE

CHOKE BYPASS

WELL FLUID OUTLET DRAIN

SEPARATOR

Function Separation of produced oil, water & gas

Rate measurement of produced fluid Provision of sampling points for re-combination samples

HORIZONTAL SEPARATOR

Horizontal Separators Primarily used for high liquid content wellsCourtesy of Expro Group

Vertical Separators Primarily used for high gas content wellsCourtesy of Expro Group

OIL BURNER

Courtesy of Expro Group

PREPARATIONOutline 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

TOOLS & SUB-SEA EQUIPMENT PREP

Outline procedureROTARY TABLE (RKB)

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

LAND-OFF POINT IN WELLHEAD

RESERVOIR FEATURE OR RA TAG

RA SUB IN TEST STRING

DISTANCE FROM RA SUB TO TOPSHOT

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