drill stem testing.1

DRILL STEM TESTINGDRILLING PRACTICES

DRILL STEM TESTING A TEMPORARY WELL COMPLETION TO GATHER INFORMATION ON THE POTENTIAL PRODUCTIVITY OF A FORMATION.WHAT IS A DRILL STEM TESTWHO REVIEWS THE DST PROGRAMOIMSENIOR TOOLPUSHEROPERATOR REPKEY SERVICE PERSONNELKEY AREAS OF REVIEWCOMMUNICATIONROLES AND RESPONSIBILITIESEMERGENCY RESPONSEEXPECTED TEST PARAMETERS Temperature Pressure HazardsREQUIRED 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 TESTWE 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 RISK

Data SourcePossible AnalysisSeismic Identify possible AccumulationsRegional InformationQualitative Accumulation size and shape using assumed Velocity ProfileHydrocarbon Prospectivity (Seismic oddities / regional information)

Degree Of Development Uncertainty = Very HighPRE-DRILLING PHASE

Data SourcePossible Analysis

Mud Log Lithology Hydrocarbon Shows Geological ProfileCore Samples Depositional EnvironmentMWD LogsQualitative HydrocarbonsPressure Regime (Qualitative) Formation Characteristics at the wellboreFluid ContactsNear-wellbore petrophysical parameters

Degree Of Development Uncertainty = HighDRILLING A WELL


Well Logs Near-well formation characteristics VSPHydrocarbon ContactsRFT SamplesLithologyQualitative HC mobilityQualitative presence of hydrocarbons (HC)Confirm Seismic velocity profileFirm-up structure mappingQuantitative Pressure regimeQualitative HC PVT analysis

Degree Of Development Uncertainty = HighOPEN HOLE LOGGING


Transient Pressure ResponseNear-well formation characteristicsSamples Near-Well Productivity Index Additional qualitative PVT analysis

Degree Of Development Uncertainty = HighLIMITED INFLUX TESTING


Transient pressure responseBulk reservoir propertiesPseudo Steady State ResponseNear-well boundaries Bulk HC SamplesIdeal Productivity IndexExtended HC PVT AnalysisTrace Element analysis (qualitative)Processing characteristics of the HCFormation Integrity (sanding tendency under high drawdown)

Degree Of Development Uncertainty = MediumCONVENTIONAL WELL TESTING


Steady State Pressure ResponseEstablish Reservoir extent Surface Process MonitoringPressure support mechanisms Wellsite Chemistry Development StrategyOptimise Process Facility designMeasure Completion PerformanceCalibrate design programs, etc.Stabilised trace element analysis Degree Of Development Uncertainty = Medium / Low

EXTENDED WELL TESTING

Test programs

Planning and preparationFor conventional wells, 2 - 3 months from expected TDFor 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

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 surfaceTESTING OPERATION

Function of DST tools

Isolation of producing interval from mud hydrostaticTest Cushion - lighter fluid than mud hydrostatic fluid columnDown hole shut-in valve to minimise wellbore storageReverse valves to kill the well at the end of the testSlip joints to compensate for tubing length changes due to temperature & pressure changesDRILL STEM TEST TOOLS

PERFORATING GUNSPACKERSAFETY JOINT / JARMEMORY GAUGESDOWNHOLE SHUT IN VALVEDRILL COLLARSPRIMARY REVERSE VALVEDRILL COLLARSDRILL COLLARSSECONDARY REVERSE VALVESLIP JOINT, CLOSEDSLIP JOINT, FULLY OPENSLIP JOINT, 1/2 OPENRA SUBDST TOOLS

Operating methods

Tools are operated by

String manipulation / rotationApplied pressure to the annulusAnnular pressureTubing pressure

Below packer and inside tubing - hydrocarbonsAbove packer in casing tubing annulus - kill weight fluid + any applied pressureDST TOOLS

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 ValveProvides the ability to isolate the tubing in the stack and disconnect without killing the well.

Lubricator ValveProvides the ability to run extended length tool strings without long sections of lubricator riser at surface.SUBSEA SYSTEMS

TEST TREEFLUTED HANGERSLICK JOINTVALVE ASSEMBLYLATCH ASSEMBLYSUBSEA TEST TREE & VALVE ASSEMBLY

COMPONENTS OF THE LANDING STRINGLATCHEDUNLATCHED

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

GENERAL LAYOUT OF WELL TEST EQUIPMENTCourtesy of Expro Group

Function

Primary pressure drop , flow controlConsists of an adjustable and a fixed choke Size of choke is usually given in 64ths of an inch, equivalent boreAdjustables used for clean-up periodFixed used once pressure has stabilisedCHOKE MANIFOLD

Function

To increase the temperature of the produced fluid downstream of the choke manifoldImproved separation efficiency

To provide a choke in a heated environmentAvoidance of hydrate formation

HEATER

HEATERWELL FLUID INLETWELL FLUID OUTLETSTEAM INLETBYPASSSTEAM OUTLETSAFETY VALVEDRAINCHOKE

Function

Separation of produced oil, water & gasRate measurement of produced fluidProvision of sampling points for re-combination samples

SEPARATOR

HORIZONTAL SEPARATORHorizontal SeparatorsPrimarily used for high liquid content wellsCourtesy of Expro Group

Vertical SeparatorsPrimarily used for high gas content wellsCourtesy of Expro Group

OIL BURNERCourtesy of Expro Group

Outline procedure

Run scrapers across packer setting depthCondition drilling mud or displace to brine Run junk basketBOP testSpace out run for sub-sea treeCourtesy of Expro GroupPREPARATION

TOOLS & SUB-SEA EQUIPMENT PREPOutline procedure

Layout toolsFunction and pressure testDrift toolsStrap lengths of toolsStrap lengths of tubularsDrift tubularsPrepare running tally ROTARY TABLE (RKB)LAND-OFF POINT IN WELLHEADRESERVOIR FEATURE OR RA TAGRA SUB IN TEST STRINGDISTANCE FROM RA SUB TO TOPSHOT

SURFACE WELL TEST EQUIPMENT PREPOutline 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

RUNNING PROCEDURESTypical Procedures on a Semi-sub

Pick up and run TCP guns and DST toolsCheck strap length between top shot and RA tagPressure test BHARun tubingPressure test tubing Perform space out / correlationPull back to sub-sea hang off pointRun subsea equipmentPick up and make up flowhead

RUNNING PROCEDURESTypical procedures on a semi-sub

Set packerCorrelation run to confirm packer setting depthPressure test landing string tools and surface tree & chokeFunction open tester valve and prepare to perforate well

TEST PROGRAMTest program determined by test objectives

Typical test programPerforate - minimal flowDown hole shut in to determine initial reservoir pressureClean-up flowInitial build upSingle rate or multi rate flow period(s)Main shut-in

TESTING PROGRAMTypical test program

Sampling flow period

Well kill

Pull test string

Validate gauge data

Abandon well

drill stem testing.1

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