Oil And Source Rock Correlation And Accumulation Mode Analysis At The Piedmont Thrust Belt In Altun,Southeast Of Tarim Basin

For the Jurassic hydrocarbon source rock and oil sand distribution of the Washixia sag and Altun thrust belt,the author carried out a field geological investigation,sample tests and analysis.The hydrocarbon generation conditions of source rocks,the geochemical characteristics and characteristics of biomarker compounds of the oil sands and the source rock was analyzed.According to the oil-oil and oil-source correlation,the source of oil sand can be divided,and the possible accumulation model can be predicted.The main hydrocarbon source rock in this area is Yang Ye formation,followed by kang Su formation.The dark mudstone in the Yang Ye group is qualified and maturity hydrocarbon source rock,which is high in thickness,wide in distribution,high in organic matter abundance,and the organic matter is type ?1 and type ?2.In addition,the distribution range of the coal mudstone and coal in KangSu Formation is less than Yang Ye formation.The hydrocarbon source rock of KangSu formation is medium-good,for medium-high organic matter abundance,which organic matter type mainly ? and ?2.The four samples of oil sands have the same maternal.The follow is the evidence:they have the similar group composition;Saturated hydrocarbon parameters show that they distribution in low carbon number and oil sand derived from the lacustrine sedimentary organic matter.In addition,the value of OEP and CPI is similar,and the correlation is very good.Based on the above,the oil sands have the same maternal.Comprehensive contrast with oil sand and hydrocarbon source rocks shows that the oil sand derived from the lacustrine mudstone of Yangye group.The group composition of them is similar,and the same and low carbon distribution shows that the oil sands parent material and the mudstone has the same organic matter inputs.A smaller ratio of pristane to phytane,display the same sedimentary environment,and to restore the environment.The distribution of C27,C28,C29 rules of sterane is similar,and the ratio of C29-20S/(20S+20R)and C29-??/(??+??)is comparison,which shows that oil sands of parent material and mudstone with the same organic matter inputs,and maturity are the same.Containing a higher concentration of tricyclic terpane shows that oil sands and parent material and source rock organic matter is lower aquatic organisms algite input is given priority too.Abnormal gammacerane index is higher and similar,which indicates they have the same reduction sedimentary environment.Based on the above,there is no genetic relationship between the ordovician shale,Yang Ye period of mudstone and kang su group mudstone.The author believe that the study area has good accumulation conditions.The Jurassic of mudstone and sandstone compose of the hydrocarbon accumulation of source rock,reservoir,cap rock and preservation conditions,and the fault and compression anticline respectively provide the migration pathway and trap conditions.On this basis,combined with the feature of tectonic development,speculated that nearly source reservoirs exist in the study area.Prediction of possible accumulation mode is proximal vertical migration accumulation model.