Naturalgascontaininghydrogensulphide(H2S)hasbeenfoundinseveralpetroliferousbasinsinChina,suchastheSichuanBasin,BohaiBayBasin,OrdosBasin,TarimBasin,etc.NaturalgaswithhigherH2Scontents(H2S＞5%mol.)ismostlydistributedinboththegasreservoirsofDukouhe,Luojiazhai,PuguangandTieshanpo,whichbelongtotheTriassicFeixianguanFormationinthenortheasternSichuanBasinandthoseoftheKongdian-ShahejieformationsinthenortheasternJinxianSagoftheJizhongDepression,BohaiBayBasin.IntheSichuanBasin,theH2Scontentsofnaturalgasaverageover9%andsomecanbe17%,whilethoseoftheBohaiBayBasinrangefrom40%to92%,beingthenoneofthegasreservoirswiththehighestH2Scontentsintheworld.Basedondetailedobservationandsampleanalysisresultsofatotal5000mofcorefromover70wellsintheabove-mentionedtwobasins,especiallysulfurisotopicanalysisofgypsum,brimstone,pyriteandnaturalgas,alsowithintegratedstudyofthegeochemicalcharacteristicsofhydrocarbons,itisthoughtthatthenaturalgaswithhighH2Scontentsresultedfromthermochemicalsulfatereduction(TSR)reactions.Amongthem,thenaturalgasintheFeixianguanFormationresultedfromTSRreactionsparticipatedbyhydrocarbongas,whilethatintheZhaolanzhuangoftheJinxianSagbeingtheproductofTSRparticipatedbycrudeoil.DuringtheconsumptionprocessofhydrocarbonsduetoTSR,theheavyhydrocarbonswereapttoreactwithsulfate,whichaccordinglyresultedinthedrycoefficientofnaturalgasincreasingandthecarbonisotopesbecomingheavier.
