Molecular geochemical characteristics of source rock in faulted lacustrine basin: A case study of the Lishu Fault Depression in southern Songliao Basin, China

(整期优先)网络出版时间:2013-04-14
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Terrestrialfaultedlacustrinebasinisconsideredasafavorableplaceforthedevelopmentofsourcerocks,especiallythefaultbasinsineasternChina.BasedonmolecularcompositionstudyofsaturatedandaromatichydrocarbonsintheextractsofsourcerocksoftheYingchengandShaheziformationsintheLishuFaultDepression,itisrevealedthattheextractsofsourcerocksareprovidedwithlowratioofPr/Ph,lowcontentofC24tetracyclicterpanes,highcontentoftricyclicterpanesandgammacerane,relativelyhighcontentofC27steranesinthesagbeltanditsperiphery;relativelyhighratioofPr/Ph,relativelyhighcontentoftetracyclicterpanesandgammacerane,lowcontentofC27steranesandobviousadvantagesofC29steranesinitsgentleslopebelt;withhighratioofPr/Ph,highcontentofC19,C20tricyclicandC24tetracyclicterpanes,verylowcontentofgammaceraneandC27steranes,andhighcontentofC29steranesintheedgeoffaultdepression.Accordingtotheorganicmatterinputandsedimentaryenvironment,threetypesofsourcerockshavebeenestablished,which,respectively,arethemodeofmixingorganicmatterinputindeepandsemi-deeplake,theadvantageofterrigenousinputinshallowlakeandterrigenousinputinshore-shallowlacustrine.Thefirstmodeissupposedtogenerateoilandgas,whilethesecondonetendstogenerateoil.ThedistributioncharacteristicsofoilandgasintheLishuFaultDepressionareverylikelytobecontrolledbyhydrocarbongeneratingcharacteristicofdifferentsourcerocktypes.