Study On Sedimentary Characteristics And Source Rocks Of Jurassic In Sikeshu Sag

This paper applies the theories and methods of sedimentology and hydrocarbon geochemistry,firstly the description and analysis of the outcrops in the field are observed,combining drilling data and seismic data,through the comprehensive analysis of outcrop,drilling data and seismic data,on the basis of summarizing the stratigraphic development characteristics of the outcrop area of the Sikeshu Sag in Junggar Basin,the sedimentary filling characteristics and geochemical characteristics of main source rocks in the study area are studied in detail,and the distribution of effective source rocks in the main source beds is analyzed,which lays a good foundation for oil and gas exploration and development in the marginal areas of the basin.The Sikeshu Sag develop Carboniferous,Triassic,Jurassic,Cretaceous,Paleogene,Neogene and Quaternary are successively from bottom to top,and Permian is absen;the Carboniferous thrusts on the Triassic.The Badaowan Formation of Jurassic in the Sikeshu Sag mainly develops Fan delta deposit;Sangonghe Formation mainly developed delta front and shore shallow lake deposits;The lower part of Xishanyao Formation mainly developed Delta front deposit,the middle part developed meandering river channel microfacies sandstone and marsh facies mudstone,and the upper part developed shore-shallow lake facies mudstone.Middle-Lower Jurassic Badaowan Formation,Sangonghe Formation,Xishanyao Formation,Paleogene and Cretaceous source rocks are developed in the depression,their hydrocarbon generating potential varies greatly.The organic matter abundance of mudstone in the Badaowan Formation is high,At low-high maturation stage,the main source rock in the area;the abundance of organic matter in source rocks in Sangonghe Formation is slightly good-good,at Immature-immature stage;the source rocks of Xishanyao Formation are medium organic matter abundance,which is low maturity source rocks.On the whole,the best source of argillaceous source rocks in the Badao Wan formation is the best,the abundance of organic matter is high,the organic matter type is better,hydrocarbon generation threshold depth(Ro=0.6%)is about 3700m,and now it is in a large number of hydrocarbon generation periods,hydrocarbon generation potential is better.The effective source rocks of the Badaowan Formation are located in the deep central area of the depression,which is NW-SE-trending,basically consistent with the overall trend of the sag,the layout area is about3500km~2,the Middle low-lying and the East low-lying in the sag are effective hydrocarbon source rocks.