測試壓裂分析

REAL-DATANETPRESSUREANALYSIS-OUTLINEIntroductionApplicationsandbriefexamplesStepsintheengineeringprocessPurpose,designandanalysisofdiagnosticinjectionsFractureclosurestressdetermination,fractureefficiencyandrequiredpadsizeRatestepdownanalysisGuidelinesfornetpressurehistorymatchingEstimatingfracturedimensions1REAL-DATAFRACTURETREATMENTANALYSISMatchingnetpressureisaNECESSARYbutnotSUFFICIENTconditionforestimatingfracgeometry2MOTIVATIONFORREAL-DATAFRACTURETREATMENTANALYSISBottomline:increasewellproductionandreducetreatmentcostbyoptimizationReducescreen-outproblemsAchieve“appropriate〞fractureconductivityandlengthControlwherefractureisgrowingDeeppenetrationinspecificlayerAvoidproductionofunfavorablecomponentsinneighboringlayers3FracturePressure

Analysis-AdvantagesBasicanalysisdatacollected(insomesense)duringeveryfractreatmentRelativelyinexpensiveandquickdiagnostictechniquetoapplyProvidesapowerfultoolforon-sitediagnosisoffractureentryproblemsAllowson-sitedesignrefinementbasedonobservedfracturebehavior4FracturePressure

Analysis-LimitationsFractureEntryFrictionEvaluationUsingsurfacepressureincreasesresultsuncertaintyProblematicnear-wellborefrictionlevelvariableNetPressureHistoryMatchingIndirectDiagnosticTechnique-fracgeometryinferredfromnetpressureandleakoffbehaviorSolutionnon-unique–careful&consistentapplicationrequiredforusefulresultsTechniquemostusefulwhenresultsareintegratedorcalibratedwithresultsofotherdiagnosticsProductiondata&welltestanalysisDirectfracturediagnostics5PrimaryFracturePressure

AnalysisActivitiesEvaluationoffractureentryfrictionPerforationfriction+near-wellborefrictionAcommoncauseoffractureexecutionproblemsNetpressurehistorymatching“Calibration〞ofmodelsolutiontoobservedfracpressuredataLinksfracturedesignandestimatedfracgeometrytoobservedfracturebehavior6DEFINITIONOFNETPRESSURENetPressureisthePressureInsidetheFractureMinustheClosurePressureNetPressure=2,500-2,000=500psi7BALLOONANALOGYFOROPENINGFRACTUREWITHCONSTANTRADIUS8FRACTUREGEOMETRYCHANGESWITHNETPRESSURETwomodelingsolutionsforthesametreatment;if500psistresscontrastexistsaroundpayzoneL=1200feetR=240feetPnet=100psiPnet=800psiPredictednetpressurePredictedfracdimensions9ESTIMATINGFRACDIMENSIONSUSINGREALDATAANDRADIALFRACASSUMPTIONFor: Volume V = 4,800bbl(~27,000ft3)(~760m3) Efficiency e = 0.5 Young’smodulus E = 2x106psi Netpressure

= 500psi Yields: R ~ 416ft

w ~ 0.8inMassbalanceElasticopening10INFLUENCEOFNETPRESSURETworadialfracturemodelsolutionsforthesametreatment(nobarriers):R = 650feetw = 0.25inR = 260feetw = 1.6inPnet = 50psiPnet = 800psiPredictednetpressurePredictedfracturedimensions11LIMITATIONSOFSIMPLIFIEDRADIALFRACCALCULATIONTOESTIMATEFRACDIMENSIONSNostressvariationsLithologyisassumedconstantPermeabilityvariationsareignoredMechanicalrockpropertiesdonotvarywithheightSimplifiedradialfluidflowNotapredictivetool12NETPRESSUREVS.FRICTIONPRESSURE13NETPRESSUREMATCHING14123415MinimumModelInputRequirementsMechanicalrockproperties–logdataFocus:Young’smodulusandpermeabilityWellcompletionandperforationsTreatmentschedule,proppantandfluidcharacteristicsTreatmentdataWith“anchorpoints〞Atleast3-secondsamplingratewithsurfacepressure,slurryrateandproppantconcentration16RequiredforNetPressureMatchingObtainsurfacepressurefromservicecompaniesrecordeddataObtainhydrostaticheadfromstagingandfluid/proppantdensitiesObtainfrictionalcomponentsfromS/DtestsObtainfractureclosurestressfrompressuredecline17DESIGNANDANALYSISOFDIAGNOSTICINJECTIONSPurposeofdiagnosticinjectionsDesignofdiagnosticinjectionsAnalysisofdiagnosticinjectionsClosurestressanalysisFrictionpressureanalysis18“TYPICAL〞FRACTURETREATMENTDATANetpressure?Closure?Leak-off?Friction?19“TYPICAL〞FRACTURETREATMENTDATAScreen-outNetpressure?Closure?Leak-off?Friction?20“TYPICAL〞FRACTURETREATMENTDATANetpressure?Closure?Leak-off?Friction?21“TYPICAL〞FRACTURETREATMENTDATADoesnotprovideenoughdata(“anchorpoints〞)todoreal-data(netpressure)fracturetreatmentanalysisUnabletomakereliableestimatesofthefracturedimensionsORItispossibletocomeupwithanyfracturedimensionyouwant,becausethereal-data(netpressure)fracturesolutionisnotbounded22REAL-DATAANALYSISISTHEKEYTOEFFECTIVEFRACSIMULATION“Usingasimulatorwithoutreal-datafeedbackislikeusingaflashlightwhilewearingablindfold〞

--BillMinner,PinnacleTechnologies23PURPOSEOFDIAGNOSTICINJECTIONSProvide“anchorpoints〞forreal-data(netpressure)analysisObtainaccuratemeasurementofthetruenetpressureinthefractureOnsitediagnosisandremediationofproppantplacementNear-wellboretortuosityPerforationfrictionfluidleakoffBottomline:provideaccurateestimatesofthefracturegeometry24RECOMMENDEDDIAGNOSTICINJECTIONPROCEDURES25ON-SITETREATMENTDIAGNOSTICS26“ANCHORPOINT〞:FRACTURECLOSURESTRESS27“ANCHORPOINTS〞:ISIPPROGRESSION28“ANCHORPOINTS〞:FRICTIONALCOMPONENTS29NEEDEDFORDIAGNOSTICINJECTIONS100to200BblofKClwater100-500Bblextracrosslinkgel(optional)Fromabout30minutesupto3hoursextrarigtimeincomparisonwithafractreatmentwithoutdiagnosticsGathertreatmentdataevery2secondsTherefore,diagnosticinjectionsarerelativelyquickandinexpensive30IMPORTANCEOFMEASURINGCLOSURESTRESSReliableestimateoffracturedimensionsObtainaccuratevalueofthenetpressureReferencedtoclosurestresslevelUsereal-datanet-pressurematchingFluidefficiencyScreen-outpotentialDirectlyrelatedtofracturedimensionsMini-fracanalysisonlyprovidesoneclosurestressvalueMoreinjectionteststoestimateclosurestressinneighboringlayersAppropriatenessofselectedproppant31EXAMPLEOFFRACTUREGEOMETRYFORALOWNETPRESSUREFracwithconfinedheightgrowth32EXAMPLEOFFRACTUREGEOMETRYFORAHIGHNETPRESSURERadialfrac33DIFFERENTMETHODSTOOBTAINFRACTURECLOSURESTRESSPressuredeclineanalysisSquare-roottimeplotG-functionplotLog-logplotRatenormalizedplotHornerplot(lowerbound)FlowpulsetechniqueFlowbacktest

Stepratetest(upperbound)HydraulicImpedancetesting(HIT)34PRESSUREDECLINEANALYSISPressuredeclineafteramini-fracpassesthroughtwoflowregimes:Linearflowregime;Pressuredeclinedependson:fluidleakoffratefracturecomplianceRadialflowregime;Pressuredeclinedependson:reservoirdiffusivityClosurestress(pressure)isidentifiedbythetransitionbetweenthetwoflowregimes35WHATCANYOUOBTAINFROMPRESSUREDECLINEANALYSIS?Fractureclosurepressure(minimumstress)FluidefficiencyLeakoffcoefficient,reservoirpermeabilityandpressureFracturegeometryestimate36PRESSUREDECLINEANALYSIS–SQUARE-ROOTTIMEPLOT37PRESSUREDECLINEANALYSIS–G-FUNCTIONPLOT38PRESSUREDECLINEANALYSIS–LOG-LOGDELTAPRESSUREPLOT39Steprate/FlowbacktestStepRateTestStartatmatrixrateIncreaseinstepsuntilfractureextended(?1to10BPM)ProvidesupperboundforclosureCandetermineifyouarefracturingatallFlowbackatConstantRatePump-In/Flowback/Shut-inTest(SPE24844)HighpermwellwheretheFB-SIisrunafterthegelcalibrationtestotherwisevolumeoffractureistosmallduetohighleakoffHere‘fracWBpinch’isidentifiedatclosure:verysmall~30psiSI-Rebound<pcindependentof"tortuosity"SPEPFFeb'97FBinduced"wellborepinch”"near-wellpinch"~15min41PRESSUREDECLINEANALYSIS-

NOCLEARSLOPECHANGEClosure?Closure?42POSSIBLESOLUTION:USEFLOWPULSETECHNIQUEOpenClosedClosureClosed43FLOWPULSETECHNIQUETOGETACCURATECLOSURESTRESSAverageclosurestressforminifracarea(relativelyfarawayfromtheborehole)Simpleandcheaptechnique:pump2ormoreflowpulseswithasmallvolumerelativetopreviousinjections(e.g.4bblat10BPM)andmeasurepressurefalloffusingstandardon-siteequipmentShouldbeusedespeciallywhenbreakinslopeinthepressuredeclinevs.square-rootoftimeplotisnotclearAccuracyontheorderoftensofpsi44PRINCIPLEOFTHEFLOWPULSETECHNIQUEFlowPulsePumpedinOpenFractureLowerstiffnessduetolargefractureradiusSmallriseinequilibratedpressureOnlyminorwidthincreasePressuredeclineslopeaspriortopumpingFlowPulsePumpedinClosedFractureHighstiffnessduetosmallfractureradiusLargeriseinequilibratedpressureLargechangeinfracturewidthFasterpressuredecline45PRINCIPLEOFTHEFLOWPULSETECHNIQUE46TORTUOSITYCANBEMEASURED:STEPDOWNTESTInstantaneousratechanges,e.g.30,20,10and0BPM--exactratesareunimportant,butchangesshouldbeabruptImplementedeasiestbytakingpumpsofflineEachratesteptakesabout20seconds--justenoughtoequilibratethepressureFracturegeometryshouldnotchangeduringstepdown--totalstepdowntestvolumesmallcomparedtotestinjectionvolume(note:pfracnotproportionaltoQ1/4duringstepdowntest)Usedifferencesinbehaviorofthedifferentfrictioncomponentswithflowrate47WHATISTORTUOSITY?WIDTHRESTRICTIONCLOSETOWELLBORE48WIDTHRESTRICTIONINCREASESNECESSARYWELLBOREPRESSURE49NetfracturingpressureTORTUOSITYLEADSTOLARGEPRESSUREDROPINFRACTURECLOSETOWELLPressureaftershut-inWellboreDistanceintofractureFracturetipNear-wellborefrictionHighLow50FRACTURESGROWPERPENDICULARTOTHELEASTPRINCIPLESTRESS--BUTWHATHAPPENSATTHEWELLBORE?51NEAR-WELLBOREFRICTIONVS.PERFORATIONFRICTION52NEAR-WELLBOREFRICTIONVS.PERFORATIONFRICTION53WHATISTORTUOSITY?SIMPLETORTUOSITYMODEL54TORTUOSITYCANBEMEASURED:STEPDOWNTESTSource:“SPEpaper29989byC.A.Wrightetal.Perforationfrictiondominatedregime55TORTUOSITYCANBEMEASURED:STEPDOWNTESTNear-wellborefrictiondominatedregime56MAXIMUMTREATINGPRESSURELIMITATIONISREACHED--CAN’TPUMPINTOZONEHighentryfrictionHighperffrictionSeverefracturetortuosityRe-perforateUseproppantslugsInitiatewithhighviscosityfluidIncreasegelloadingIncreaserateFuturewellsmayhavealteredcompletionstrategysuchasFEWERperfs57NETPRESSUREMATCHINGMatch“observed〞netpressurewithcalculated“model〞netpressureObservednetpressureobtainedfromsurfaceordownholetreatmentpressureCorrectforfractureclosure,frictionaleffectsandhydrostaticModelnetpressurecanbechangedtomatchobservednetpressuresusingthefollowinggeneral“knobs〞(seenextpage)58HISTORYMATCH“ANCHORPOINTS〞:FRACTURECLOSURESTRESS,FLUIDLEAKOFFANDISIPPROGRESSION59HISTORYMATCH“ANCHORPOINTS〞:FRACTURECLOSURESTRESS,FLUIDLEAKOFFANDISIPPROGRESSION60KEYVARIABLESFORNETPRESSUREHISTORYMATCHING61EFFECTOFFORMATIONYOUNG’SMODULUSModulusshouldbeobtainedfromstatictests(preferablysimilartofracturingconditions)Dynamicmodulustwotimesormorelargerthanstaticmodulus(usewithcaution!)Oncemodulusisdetermined,thisshouldbeaFIXEDparameterinanetpressurematchingproceduresAnincreaseinYoung’smodulusresultsinlessfracturewidth(forthesamenetpressure)Forsimpleradialmodel:Lfrac

E1/3(forthesamenetpressure)Modelingresultsnotextremelysensitivetomodulus.62EFFECTOFFRACTURECLOSURESTRESSCONTRASTClosurestressprofiledeterminesfractureshapeRadialifstressprofileisuniform(theoreticaldecreaseinnetpressurewithpumptime)Confinedheightgrowthifclosurestress“barriers〞arepresent(theoreticalincreaseinnetpressurewithpumptime)Effectivenessof“barrier〞determinedbyClosurestresscontrastLevelofnetpressure“Typical〞sand-shaleclosurestresscontrast0.05-0.1psi/ftHigheriftherehasbeensignificantdepletion(~2/3ofporepressurechange)Lowerifsandsandshalesarenotclean63CLOSURESTRESSPROFILEClosurestress

mindeterminesminimumpressuretoopenafractureUsuallyclosureincreaseswithdepthClosurestressislithologydependent(shalesusuallyhigherthansands)Representsonlytheminimumprincipalstresscomponentinthevicinityofthewell64DEPLETION:INCREASEDEFFECTIVESTRESS;DECREASEDTOTALSTRESSReservoirPoresRockMatrixUntappedReservoirProducingReservoirIncreasedEffectiveStressDecreasedTotalStress65MANYEFFECTSOFDEPLETIONINDUCEDSTRESSCHANGESAREWELLKNOWNDecreasesinTotalStress:Lowerfracgradientindepletedzones(refracs,etc.)FracturecontainmentwithindepletedintervalsIncreasesinEffectiveStress:Reservoircompaction(surfacesubsidence)ReducedconductivityofproppedfracsReductionofreservoirporosity(andpossiblypermeability)ReservoirDepletionResultsIn:66POREPRESSUREVARIATIONSCHANGEFRACTUREORIENTATIONsource:SPEpaper29625byWrightetal.67POREPRESSUREVARIATIONSCHANGEFRACTUREDIMENSIONS68HEIGHTGROWTHDUETOLEVERAGE69HEIGHTGROWTHDEPENDSONSTRESSCONTRASTANDNETPRESSURE70EQUILIBRIUMFRACTUREHEIGHTLeveragebyopeningofafracureleadsto(limited)heightgrowth--alsoifthenetpressureislowerthantheclosurestresscontrast71HOWISHEIGHTGROWTHAFFECTEDBYPERMEABILITYBARRIERSApermeabilitybarrierwithextremepermeability(e.g.1Din10mDformation)mayconfinefractureheightgrowthSource:T.Quinn,Ph.D.Thesis,MIT72COMPOSITELAYERINGEFFECTSLOWSDOWNFRACTUREHEIGHTGROWTH73EFFECTOFFRACFLUIDLEAKOFFFormationpermeabilityunderfracturingconditionscanbeverydifferentfromperm“seen〞byproductionrelativepermeabilityforfracfluidopeningofnaturalfracturesPermeabilitygenerally“fixed〞innetpressurematchbyinitialKClinjectionpressuredeclineWallbuildingcoefficientforcrosslinkgel“fixed〞byminifracpressuredeclineEnd-of-jobpressurecanshowdifferentleakoffbehaviorthanmini-frac.ItisKEYtomatchpost-fracpressuredeclinetoobtainrealisticfracturedimensions74FRACTURINGFLUIDLEAKOFFFractureFiltercakeInvadedZoneReservoirFiltercakeFractureInvadedZoneReservoir<1/10inch0.5to

3feetTypicalExtent100’soffeet75FLUIDLOSSEQUATIONSCkpvia

0046912./

CpkCcrrr

0037412./

CmAw

00164.(MeasuredinLab)ki=PermeabilitytoFiltrate,darcies

p =(

x+pnet)-p,psi

=FormationPorosity,fraction

a =ViscosityofFiltrate,cpkr =PermeabilitytoReservoirFluid,mdCt =TotalCompressibility,psi-1

r

=FormationFluidViscosity,cpm =SlopeofVolumevstGraphA =AreaofCoreUsedtoMeasureCwFluidlossininvadedzone:Fluidlossinvirginzone:Fluidlossinfiltercake:FracproPTmodelsACTUALpressuredifferentialversustime76FLUIDLEAKOFFANDSLURRYEFFICIENCYLOWSLURRYEFFICIENCYShortFractureHighFiltrationLongerFractureHIGHSLURRYEFFICIENCYLowFiltrationVpumpedVfracEfficiency=77EFFECTOFPROPPANTINFRACTUREProppantcanreachthefracturetipand“bridge〞,resultinginatipscreen-out.ThiscanhappenifFluidleakoffisrelativelyhighVolumefractionofproppantinthefractureishighIfatipscreen-outoccurs,onlythewidthofthefracturecangrowLinearincreaseinnetpressurewithvolume(Nolte’sunitslope)78WHATISPROPPANTCONVECTION?DOWNWARDTRANSPORT

OFDENSESLURRY79WHATISPROPPANTSETTLING?DOWNWARDTRANSPORTOF

DENSEPROPPANTGRAINSINFLUID80PROPPANTCONVECTIONFASTERTHANPROPPANTSETTLINGw = Fracturewidth

d = ProppantdiameterRatioVc/Vs~100-1000(Maybemuchhigherduetoencapsulation)81PROPPANTCONVECTIONFASTERTHANPROPPANTSETTLINGDUETOENCAPSULATIONheavyslurrylightslurryorpadfluidSource:SPEpaper24825byM.P.Clearyetal.82WHATARETIPEFFECTS?

NON-LINEARELASTICROCKBEHAVIOR/“TIPPROCESSZONE〞Non-linearrockbehavioratlargedifferentialcompressionalstressRockmayswellwithlargeconfiningstressesintwodirectionsandnoconfinementintheotherdirectionTipprocesszone(withopeningfractures)slowsdownfracturegrowthFracturewidthnearthefracturetipsmallerthanexpected83TIPEFFECTS--INCREASEDFRACTUREGROWTHRESISTANCE84PROCESSZONEAROUNDFRACTURETIPExperimentsbyShlyapoberskyrevealfractureprocesszoneProcesszoneisscaledependent,andresultsinmultiplefracturesaheadofhydraulicfracturetipCanresultinhighernetpressurestopropagatefracture85CONSEQUENCESOFTIPEFFECTS:INCREASEDNETPRESSUREANDFRACTUREWIDTHNon-linearelasticmodelLinearelasticmodelpnetLfNon-linearelasticmodelLinearelasticmodelwfracLf86EvidencefortheSimultaneousPropagationofMultipleHydraulicFracturesCorethroughandminebackexperimentsDirectobservationsofmulti-planarfracturepropagationFracturegrowthoutsideplaneofwellboreObservationofhighnetfracturingpressuresContinuousincreasesinISIPsforsubsequentinjections

Conclusion:multiplefracturesaretheruleratherthantheexception87CausesofMultipleHydraulicFractureGrowth88MultipleStrandsinaProppedFractureNEVADATESTSITEMINEBACKCourtesy:N.R.Warpinski,SandiaLabs89M-SITEBSANDINTERSECTINGWELLCorePhotoProjectedBoreholeFMSImageF11F10F9F8F7F6F5F4F3F2F146754676467746782-1/2in.Coredia.Courtesy:N.R.Warpinski90CONSEQUENCESOFMULTIPLE

HYDRAULICFRACTURES:INCREASEDNETPRESSURE91ConsequencesofMultipleHydraulicFractures:ReducedDimensionsandWidth9293UseMultipleHydraulicFracturesPrudentlyforModelingPurposesPotentialcausesforhighnetpressures:ConfinedfractureheightgrowthIncreasedfractureclosurestressduetoporepressureincreaseHigherYoung’smodulusthananticipatedFracturetipeffectsTipscreen-outinitiationSimultaneouslypropagatingmultiplehydraulicfractures94VenturingintotheDeep,DarkWorld

ofFracproPTMultipleFractures……...F9ReservoirParameters“MultipleFractures〞Screen“FracproPTisthemostpowerfulandversatile

fractureengineeringsystemavailable〞Translation:

*TherearemanywaystoscrewupUsingasawandahammer,itiseasiertomangleyourfingersthanto

buildfinefurnitureSolution:Carefulandconsistentmultiplefractureusage(methodology)Tableusagemustmakesenseconsideringrockandcompletion

characteristics!ChangemultiplefracturesettingsonlyduringpumpingFRACTUREGEOMETRYRESULTINGFROMDIFFERENTPERFORATIONSTRATEGIES96MULTIPLEHYDRAULICFRACTURESINFRACPRO97MULTIFRACMODELINGAPPROACHFORLIMITED

DIFFERENTPERFORATIONSTRATEGIES98ModelingApproachforMultipleHydraulicFractures

SituationEquivalentnumberofgrowingmultiplefracs(MV)Equivalentnumberoffractureswithleakoff(ML)Equivalentnumberoffracscompetingforwidth(MO)331322313EquivalentnumberofspacedidenticalfractureswithoutinterferenceEquivalentnumberoffracturescompetingForwidth99APPLICATIONSOptimizationofbasictreatmentandcompletiondesignSolvingfractureentryfrictionproblemsRoutineon-sitepadvolumesizingtoaccommodategeologicvariabilityDesignfornewfracturingenvironment100EXAMPLEAPPLICATION--“PRESSURE-OUT〞ONPADFormation: Naturallyfractureddolomite@8900’(gas)Completion: 5-1/2〞casingfracstring,max.pressure6000psi; 70’perfintervalshotat4SPF,90,0.45〞diameter hole; Previouslyacidizedwith70gallons/ft20%HClSituation: Declininginjectivityleadingto“pressure-out〞onpadDiagnosis: Severenear-wellborefracturetortuositySolution: 1and2PPGproppantslugsveryearlyinthepadto screenoutfracturemultiples101EXAMPLEAPPLICATION--“PRESSURE-OUT〞ONPADTime(mins)Surfacepressure(psi),Proppantloading(ppg)Slurryrate(bpm),Bottomholeprop.concentration(ppg)0.030.060.090.0120.0150.00120024003600480060000.020.040.060.080.0100.00.004.008.0012.0016.0020.000.004.008.0016.0020.001400psireduction(1stslug)SurfacepressurelimitationS/D#2:300psitortuosityIncreasedmaxproppantconcentrationS/D#1:1700psitortuosity;smallperffric.zerotortuosityatendofpumping102EXAMPLEAPPLICATION--“PRESSURE-OUT〞ONPADEarlierwellsinneighborhoodpressured-outonpadProppantslug(1ppg)pumpedearlyinthetreatmentpreventedupcomingpressure-outandreducedtortuosityby1400psiTortuosityreductionallowedpumpingtreatmentfarbelowsurfacepressurelimitof6000psiBasedonpressureresponse,maximumproppantconcentrationcouldbeincreased(from4to6ppg)inreal-timetoobtainhigherfracconductivityTreatmentresultedin3-foldproductionincrease(incomparisontoafteracidtreatment)to3MMSCFD103EXAMPLEAPPLICATION--REALISTICESTIMATIONOFFRACTUREHALF-LENGTHFormation: Hardsandstone@7600’(gas)Completion: 5-1/2〞casingfracstring;40’perfintervalshotwith4 SPF,90phasing,0.31〞diameterholesSituation: Disappointingproductionperformanceforexpected 600ftfracturehalf-length(basedonfracturegrowth modelingwithoutreal-datafeedback)Diagnosis: Sand/shalestresscontrastmuchlowerthan estimated,resultinginsignificantfractureheight growthandamuchshorterfracturehalf-length(250’)Solution: Utilizefracturepressureanalysistooptimizefracture treatmentdesign104EXAMPLEAPPLICATION--REALISTICESTIMATIONOFFRACTUREHALF-LENGTHObservednetpressurecouldnotbematchedusinginitialassumptionofalarge0.2psi/ftsand/shalestresscontrast.Withasmallersand/shalestresscontrast(0.05-0.1psi/ft),thefracturegrowssignificantlyinheight,resultinginamuchshorterfracturehalf-length105EXAMPLEAPPLICATION--REALISTICESTIMATIONOFFRACTUREHALF-LENGTHBasedondipole-sonic,initialsand-shalestresscontrastwasestimatedat0.2psi/ftEstimatedfracturehalf-lengthof600ftProductionresponsewasrelativelylowNetpressurebehaviorcouldnotbematchedwithclosurestresscontrastassumption.Netpressurematchforcontrastof0.1psi/ftActualfracturehalf-lengthabout250ftActualclosurestressdirectlymeasured,andconfirmednetpressure-inferredvalueRealisticfracturehalf-lengthandreal-dataanalysisusedtooptimizefracturetreatmentstrategy106EXAMPLEAPPLICATION--TIPSCREEN-OUTSTRATEGYTOOBTAINSUFFICIENTCONDUCTIVITYFormation: Highpermeabilitylayeredsandstoneat6000ft(oil)Completion: Deviatedwellbore,3-1/2〞tubingfracstring 30’perfintervalshot4SPF,180phasingoriented perfs,0.5〞diameterholesSituation: Relativelypoorpost-fracproductionresponseforhigh permreservoirDiagnosis: InsufficientproppedfractureconductivitySolution: Increasetreatmentsize,andutilizeon-sitefracture pressureanalysistoconsistentlyachievetip screenoutforenhancedfractureconductivity107EXAMPLEAPPLICATION--TIPSCREEN-OUTSTRATEGYTOOBTAINSUFFICIENTCONDUCTIVITYPadsizingforTSOdesignwasdoneutilizingleakoffcalibrationwithminifrac.Thenetpressurematchshowsasignificantincreaseinpressureduetotipscreen-outinitiationBreakdowninjectionMinifracPadfluidvolumeadjustedbasedonleakoffbehaviorfollowingcrosslinkgelminifracTipscreen-outinitiation108EXAMPLEAPPLICATION--TIPSCREEN-OUTSTRATEGYTOOBTAINSUFFICIENTCONDUCTIVITYProductionresponseinKuparukAsandlimitedbyfractureconductivityTipscreen-outobtainedinmorethan90%oftreatmentsSizingofpadsizeusingcalibrationofleakoffcoefficientkeytosuccessOn-sitereal-timeclosurestressanalysisimplementedoneverytreatmenttoensureproperpadsizeispumped109HONORINGREAL-DATA:EXAMPLEOFFRACTREATMENTINJAPANExtremelyhighnetfracturingpressuresinadeepgaswellinJapanesevolcanicreservoirCausedbysomedegreeofsimultaneouspropagationofmultiplehydraulicfracturesExampleprovidesroughboundsfortrade-offbetween“tipeffects〞andpropagationofmultiplefracturesResultedinverynarrowfracturewidth(poorconductivity)andveryearlyprematurescreen-outProduction/pressurebuild-uptestshowshorteffectivefracturehalf-length(~45ft)that“disappears〞withearlyproduction