【7A文】Gohfer-培训英文课件-unconventional-reservoir-stimulation

1、UnconventionalReservoirStimulationR.D.BarreeBarree&AssociatesLLCHowDoWeOptimizeStimulationDesigns?Experience Ourpersonalobservations Ourpasthistory OurexpectationsofwhatwillbesuccessfulDiagnostics Pumpintests Fracturemapping Tracers(chemicalandRA)Reservoircharacterization Loganalysis CorestudiesMode

2、ls Fracturegeometry LEFM,planar,2D,3D,coupled,sheardecoupled? Reservoirproduction singlephase,multiphase,transient,infiniteacting,isotropic,Darcy?Are these transferable from conventional to unconventional?20092009WhatAreUnconventionalReservoirs?Tightandultratightgassands Permlessthanwhat?0.01md? Com

3、posedof Fluvialchannelsandlenticularsands AnisotropicanddiscontinuousbodiesGasshales Whatisashale,anyway? Typicallylessthan2030%clay Maybequartziticorcarbonaceous Finegrained,smallporesize,highTOC? Whatistheproductionmechanism? Darcyslawforfreegasflow? Diffusionfromkerogen? Howdoweestimategascontent

4、andrecoveryCoalbedMethane Wetordrycoals? Whatisthepermeabilityofthecleatsystem? Whatcontrolsgascontentandrecovery? Desorptionisotherm? Dewateringorrateofpressuredecline?2009PuzzlesforUnconventionalReservoirDevelopment PayidentificationandGasInPlace Porosity,saturation,TOC,desorptionisotherm,netpay,d

5、rainagearea,aspectratio Permeability PorosityandSwrelations,stressdependence,effectsoffractures,capillaryeffects(permjail?)Stimulationdesign fracgeometryProductionforecastingandEURApplyingpressurediagnosticsManagingstimulationdamagePerforating2009GasStoragev.FracPlacementandProduction Logs(DTCstepou

6、t)helpshowgasandTOCcontent Areasofhighgascontentmaynotbeproductive Gasistherebecauseitistrapped Gasmaybeathighpressure,increasingfracgradient Highstressandno“natural”fracturesmeansnofracplacementorproduction Howdoweidentifybestfracplacementtocontactstoredgas?2009LogDerivedKHRarelyWorksinUnconvention

7、alReservoirs Porositydoesnotcorrelatewelltopermeability Poresizeandsizedistributionareneeded Saturation(orresistivity)maybemisleading Distributionofphases,wettability,claymorphology(notvolume)maybeimportant Small,sparsenaturalfracturescontributetoeffectivepermeabilityintightrock2009GasRecoveryMechan

8、ismsinCoal2009PorosityofCoalsMacropores ( 500 Angstroms) Space within cleats and natural fractures primarily determines the storage capacity for water considered to vary between 1-5%Micropores (8 to 20 Angstroms)Capillaries and cavities of molecular dimensions in the coal matrixEssential for gas sto

9、rage in the adsorbed stateGas is adsorbed on particle surface98% of methane is typically adsorbed in the microporesStorage capacity is equivalent to 20% porosity sandstone of 100% gas saturation the same depth 1 lb of sample Fruitland coal has an estimated internal surface area of325,000 to 1,000,00

10、0sqft A very large volume of methane can be stored in the micropores of coaldespite low porosity in the cleat system.2009TypicalSizeDistributioninCoalPorosity2009Gas Storage & Transportation Mechanism inCoals (contd.)2009Saturation vs UndersaturationPermeability Change withShrinkageMatrix shrinkage:

11、 Coal matrix shrinks asgases desorb and thiscauses an enlargementof the adjacent cleatspacing increasedpermeability Effect increases withadsorbate affinity forcoals (i.e. effect is morefor the desorption ofCO2 than for methane)20092009ShaleGasProductionFollowsaSimilarModel2009ShaleGasContent:Freeand

12、AdsorbedGas2009EffectofSwofEffectiveGasPermeabilityforLowPermSystems2009QHPbL=Flow rate (bbl/day)Height of fracture (ft)Pressure differential (psi)Fracture aperture (in)Length of fracture (ft)Fluid viscosity (cp)FlowThroughSmoothSurfacedFracture,TheCubicLawEquation6HPb32009EffectofFracturesonSystemP

13、ermeabilityforParallelFlowAssumed Fracture Aperture = 0.001”Matrix Perm2009CorePermeabilityChangeswithStressCycling2009UnproppedFractureConductivityLosswithStressWhatKindofFracDoWeNeed? SingleplanarfracLimitedsurfaceareaAllflowpassesthroughasmallchannelRequireshighconductivityProductiondependentonfr

14、acconductivityandreservoirperm Complex(shear)fracturenetwork Largesurfaceareaexposed Maynotbeabletoconnectanddrainentirenetwork(loadrecoveryexperience) Fractureconductivitymaybelessimportant(exceptnearthewell,butmustbemeasurable) Productiondependentoneffectivesurfacearea(diffusiondominated)20092009C

15、omplexFractureNetworkorSimplePlanarFrac?SPE 90051, Fisher et al, 20042009SimpleModelforComplexTransverseFractures2009IncreaseinExposedFormationAreawithMultipleFractures2009EstimatingEURandProductionDeclineCurveAnalysis Producedatcapacity ProducedatconstantBHP Drainageareamustremainconstant Onlyvalid

16、inboundarydominatedflow(whenisthat?)MaterialBalanceReservoirfluidsinphaseequilibriumAccuratefluidpropertiesandproductiondataReservoirsaturationsareuniformthroughoutReservoirpressurecanberepresentedbyasingleaveragevalue(whatisit?)RateTransientAnalysisHomogeneous,isotropicreservoirSinglePhaseflowing(w

17、aterandcondensateimmobile)Isothermal,laminarflow(negligiblenonDarcyeffects)Gasmaterialbalanceisvalid(noactivewaterdrive)SPE 78695, Cox et al(tDA)pssctAtpss =r(tDA) pss =Where -()+WL=2009EstablishingtimetoPss/BDF ByusingthefollowingequationareasonablereLestimatecanbemade:0.006328k2e4AWW L162009HowLon

18、gUntilDeclineCurvesareValid? 4 days 1 month2009EvaluationofTechniquesforReserveForecasting EclipseSimulationCase:channelflowDrainage Area 160 acresModel ParametersFormation Top, ftInitial Reservoir Pressure, psi10,0005,000Net Pay, ft40Gas Specific GravityEffective Gas Perm. MdFracture Half Length, f

19、tFracture Conductivity, md-ft0.650.05200500600 ftOGIP4.1 BcfRec.1.9 Bcf after 30 yearsEUR 2.8 Bcf after 81 yearsSimulation Controls Flowing tubing pressure of 100 Psia Economic limit 30 mcfpd and/or 30 years Single layer systemsGas Rate (Mscf/D)Gas Rate (Mscf/D)P/Z (psia)2009100010000100Jan-02Jan-03

20、Jan-04Jan-05Jan-06Jan-07Jan-08Jan-09Exponential, Di =1.18, EUR=448 MMscfHyperbolic b=1.75, Di=3.03, EUR=1,720 MMscfHarmonic b=1.0, Di=2.39, EUR=942 MMscf180 Days of ProductionSimulation Data10001001000010Jan-02Jan-04Jan-06Jan-08Jan-10Jan-12Jan-14Jan-16Jan-18Time to Pseudo-Steady StateDecline Estimat

21、e after Reaching Pseudo-Steady StateSimulation DataExponential, Di =0.033 EUR=2,367 MMscf0600050004000300020001000050010001500200025003000350040004500Gp (MMscf)P/ZMaterial Balance - Simulation Case 2Initial PressureSimulation Average Pressure7-day final shut-in pressure1-day final shut-in presure Hy

22、perbolic exponent 1(still transient) Time BDF 5450 days Exponential declineUnder-predicts EUR at 180 days over-predicts EUR after BDF SI required to reach avg. press (P/z) 100 yrsEUR results after 180 days of productionPwD or PwD1/PwDPwD or PwD1/PwDGas in Place = 0.68 BCF - Equivalent Area 27 acres

23、- 180 Days0.00.51.01.52.52.03.000.020.040.060.080.10.120.140.16QDASimulationAnalytical0.11101000.010.000001 0.000010.00010.0010.010.1110100tDASimulation PwDSimulation PwDAnalytical PwDAnalytical PwDFinite Conductivity Fracture in 18.6 to 1 Rectangular Boundary Post BDFGas in Place = 4.06 BCF - Equiv

24、alent Area 160 acres - Post BDF0.00.51.01.52.52.03.000.020.040.060.080.120090.120.140.16QDASimulationAnalytical0.11101000.010.000001 0.000010.00010.0010.010.1110100TDASimulation PwDSimulation PwDAnalytical PwDAnalytical PwDInfinite Conductivity Fracture in 3.1 to 1 Rectangular Boundary at 180 DaysWi

25、th transient analysis, you know when BDF occurs2009EstimatingReserves Inunconventionalreservoirsitcantakeyearstoestablishboundarydominatedflow Anaccuratepressurebuildupformaterialbalance(P/z)cantakeyears Doreservoirscontrolledbydesorptioneverbehaveasvolumetricsystems? Onlyratetransientanalysiscangiv

26、einsightsinto: Drainageaspectratio Transientflowregimes Effectivenessofstimulation2009PressureDiagnostics Gfunctionandloglogflowregimeplotsforconventionalandunconventionalreservoirs Doesinjectedfluid(water)enterporesforcoalandshaletoestablishareservoirpressuretransient? Canwediagnosefracturesystemex

27、tentorconductivityfromfalloffbehavior?Gfunctionina“Shale” thatlookslikeareservoirGohWin Pumping Diagnostic Analysis ToolkitMinifrac - G Function1020304050607080G(Time)200985009750950092509000875010500102501000010750A0120010008006004002001800160014002000D(0.002, 0)(m = 48.16)(34.1, 1642)(Y = 0)Bottom

28、 Hole Calc Pressure (psi)Smoothed Pressure (psi)1st Derivative (psi)G*dP/dG (psi)AADD2112End of PDLClosureTime3.7212.02BHCP102169822SP102189827DP447.7841.6FE66.3486.507 days of falloff with apossible closure at G12101001000PostClosureReservoirTransientina“Shale”TestGohWin Pumping Diagnostic Analysis

29、 ToolkitMinifrac - Log Log234567 8 9234567 8 9234567 8 9234567 8 9234560.11Time (0 = 9.216667)200932445298761032100 987651000A01030205040B(0.87, 59.96)(m = 0.5)(673.3, 1668)(Y = 20.33)(576.9, 359.7)(m = -0.502)(1430, 228.1)(Y = 106.6)Delta Bottom Hole Calc Pressure (psi)Delta Smoothed Pressure (psi)

30、Smoothed Adaptive 1st Derivative (psi/min)Adaptive DTdDP/dDT (psi)AABABH ISIP = 10664 psi11ClosureTime173.62DBHCP841.7DSP837.0FE86.502009CoalInjectionTest:Isthisafracturetest?2009CoalInjectionGFunctionInterpretationBottom Hole ISIP 7216 psi (0.91 psi/ft)Closure Pressure 5939 psi (0.75 psi/ft)2009Coa

31、lInjectionLogLogPlot2009SimulationofRadialInjectionintoReservoir(constperm)2009RadialInjectionSimulationGFunction2009RadialInjectionSimulationLogLog23:585/16/200700:005/17/200700:0200:0400:0600:0800:10 2009 00:125/17/2007Time150050004500400035003000250020005500A0.03.02.52.01.51.00.53.5BBH Gauge Pres

32、sure (psi)Clean Rate (bpm)AB21CoalInjection:BHGaugeISIPGohWin Pumping Diagnostic Analysis ToolkitJob DataMinifrac Events123StartShut InStopTime5/17/2007 00:00:095/17/2007 00:05:145/17/2007 08:07:01BGP319149362604CR2.5280.1180.050(ISIP = 4839)ISIP=1.14 psi/ftEarlytimeGfunctioninadeepcoalGohWin Pumpin

33、g Diagnostic Analysis ToolkitMinifrac - G Function0.51.01.52.02009 2.5G(Time)340044004200400038003600500048004600A0500400300200100800700600D(0.0023, 0)(0.3993, 535.7)(m = 1349.4)(Y = 0)BH Gauge Pressure (psi)Smoothed Pressure (psi)1st Derivative (psi)G*dP/dG (psi)AADD11ClosureTime BGP0.24 4473SP DP

34、FE4532 365.1 11.71First closure at 1 psi/ftLatetimeGfunctionfordeepcoalGohWin Pumping Diagnostic Analysis ToolkitMinifrac - G Function51015202009G(Time)25002750375035003250400047505000A0100200300040030050045006004250700800D(0.002, 0)(m = 83.89)(6.388, 535.7)(Y = 0)BH Gauge Pressure (psi)Smoothed Pre

35、ssure (psi)1st Derivative (psi)G*dP/dG (psi)AADD11ClosureTime BGP5.90 3220SP3225DP FE1619 75.8210100 2009LogLogFlowRegimePlotforDeepCoalGohWin Pumping Diagnostic Analysis ToolkitMinifrac - Log Log2345678 922345678 9 23413 4 5 6 7 8 9Time (0 = 5.233333)32100.1432100 987654321000 98765(m = 0)(m = -0.184)Delta Bottom Hole Calc Pressure (ps