煤层气非达西流Effects of non-Darcy flow on the performance of coal seam gas wells

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1、InternationalJournalofCoalGeology93(2012)62–74ContentslistsavailableatSciVerseScienceDirectInternationalJournalofCoalGeologyjournalhomepage:www.elsevier.com/locate/ijcoalgeoEffectsofnon-Darcyflowontheperformanceofcoalseamgaswellsa,⁎,AkimKabirbaaJ.G.Wang,JishanLiu,ZhongweiChenaSchoolofMechanica

2、landChemicalEngineering,TheUniversityofWesternAustralia,35StirlingHighway,Crawley,WA6009,AustraliabQGC—ABGGroupBusiness,275GeorgeStreet,Brisbane,QLD4000,AustraliaarticleinfoabstractArticlehistory:Althoughithasbeenreportedthatthegasflowinthecleatsystemmaybeofthenon-Darcynature,littlehasReceived

3、25November2011beenknownonhowthisnon-Darcyflowaffectsthecoalseamgas(CSG)extraction.OneofthemajorreasonsReceivedinrevisedform24January2012isthatpriorstudiesonthissubjecthavenotincludedtheimpactofgassorption-inducedcoaldeformationAccepted26January2012(swellingorshrinking)andthenatureoftwoextremel

4、ydifferenttimescalesbetweenprocessesintheAvailableonline10February2012coalmatrixandonesinthecleatsystem.Inthisstudy,afullycoupledfiniteelement(FE)modelofcoalde-formation(gassorptioninducedswellingorshrinking),non-DarcyflowinfracturesandgasdiffusionincoalKeywords:Non-Darcyflowmatrixisdevelopedtoq

5、uantifythesenon-Darcyfloweffects.ThefullycoupledmodelcanincludeEDMCoaldeformation(EquilibriumDesorptionModel)orDDM(DynamicDesorptionModel).InEDM,thegassorptioninthema-Swellingandshrinkagetrixsystemisafunctionofgaspressureonly,i.e.,thesorptionprocesscompletesinstantlywhenthecleatPermeabilitycha

6、ngepressurechanges.InDDM,thegassorptioninthematrixsystemisafunctionofbothgaspressureintheCoalgasdiffusioncleatandthediffusiontimeinthematrix,i.e.,atimelagbetweenthecleatflowanddiffusionprocessinthematrixexists.WhenonlyDarcyflowisassumed,thismodelwasverifiedagainstboththemodelresultsofaverticalga

7、swellperformancebyusingECLIPSEandfielddatafromtheHorseshoeCanyoncoalbedgaswell.BothEDMandDDMareappliedtoquantifytherelationshipamongnon-Darcyeffect,productionpa-rameters,diffusiontimes,andcoalseamcompaction.Modelresultsindicatethatthenon-Darcy