简介：Thermalmaturationandpetroleumgenerationmodelingofshalesisessentialforsuccessfulexplorationandexploitationofconventionalandunconventionaloilandgasplays.Forbasinwideunconventionalresourceplayssuchmodeling,whenwellcalibratedwithdirectmaturitymeasurementsfromwells,cancharacterizeandlocateproductionsweetspotsforoil,wetgasanddrygas.Thetransformationofkerogentopetroleumisassociatedwithmanychemicalreactions,butmodelstypicallyfocusonfirst-orderreactionswithratesdeterminedbytheArrheniusEquation.AmisconceptionhasbeenperpetuatedformanyyearsthataccuratethermalmaturitymodelingofvitrinitereflectanceusingtheArrheniusEquationandasingleactivationenergy,toderiveatime-temperatureindex(∑TTIARR),asproposedbyWood(1988),isflawed.ThisclaimwasinitiallymadebySweeneyandBurnham(1990)inpromotingtheir'EasyRo'method,andrepeatedbyothers.Thispaperdemonstratesthroughdetailedmulti-dimensionalburialandthermalmodelinganddirectcomparisonofthe∑TTIARRand'EasyRo'methodsthatthisisnotthecase.The∑TTIARRmethodnotonlyprovidesaveryusefulandsensitivematurityindex,itcanreproducethecalculatedvitrinitereflectancevaluesderivedfrommodelsbasedonmultipleactivationenergies(e.g.,'EasyRo').Throughsimpleexpressionsthe∑TTIARRmethodcanalsoprovideoilandgastransformationfactorsthatcanbeflexiblyscaledandcalibratedtomatchtheoil,wetgasanddrygasgenerationwindows.Thisisachievedinamore-computationally-efficient,flexibleandtransparentwaybythe∑TTIARRmethodthanthe'EasyRo'method.Analysisindicatesthatthe'EasyRo'method,usingtwentyactivationenergiesandaconstantfrequencyfactor,generatesreactionratesandtransformationfactorsthatdonotrealisticallymodelobservedkerogenbehaviourandtransformationfactorsovergeologictimescales.