Sedimentary Facies Study Of Jurassic Yangxia Formation In Yangxia Region Of Tarim Basin

Based on predecessors’ work, this paper combined with drilling data, seismic data, logging data interpretation and analysis of Jurassic Yangxia formation in Yangxia region of Tarim basin has carried on the stratigraphic division and correlation, believe the characteristics of layer development in the study area is more close to the northern Tianshan belt formation thickness, the greater the latitudinal direction degressive trend toward the south, for the east-west direction near the Kuqa river section and near the Yishen 4 well in deep strata thickness is relatively large.Based on accurate correlation of strata, combining with the results of single well facies and section facies, through statistical of the thickness of sand body, drew the thickness of sand body figure, using the superiority of compilation method of different period layout and analysis of plane distribution of sedimentary facies sedimentary facies evolution in the area.On the basis of Yangxia region of the field profile and the drilling core, single well facies and section facies, seismic facies and provenance analysis, etc, the Jurassic Yangxia formation of sedimentary facies in the studied area has carried on the system analysis and research, think: in 4 lithologic section of Jurassic Yangxia group in the study area, the below and uper mudstone of coal seam segments mainly developed meandering river delta plain subfacies, can further identify the meandering river delta plain distributary channel, interchannel and swamp microfacies; the Glutenite segment are mainly in braided river delta plain subfacies, can identify the braided river delta plain distributary channel and interchannel microfacies; Carbonaceous mudstone segment developed shore shallow lake subfacies. The meandering river delta plain subfacies in the upper mudstone of coal seam segment compare with the below mudstone of coal seam segment,the coal seam and sandstone content reduce, mudstone content increases, sand clay ratio decreases, and this time water to deepen; Throughout the Yangxia formation sedimentary period, transition from the meandering river delta plain sedimentary system of braided river delta plain, then transition to meandering river delta plain, finally to shore and shallow lake sedimentary system, overall for the process of lake invasion with lake retreat; Source mainly comes from the northern Tianshan direction,and the south Tianshan provenance can be roughly divided into four classes.