Study On Sedimentary Facies Of N1s2 Of Shawan Formation In The Chepaizi Area

Chepaizi is a important oil and gas area in the Junggar Basin of our country,and the Shawan formation is the main reservoir system in recent years,but the research and understanding of the N1s2 of Shawan formation is relatively low,and it still exists the basic geological problems in the exploration of oil and gas.The thesis is focused on the the N1s2 of Shawan formation of Chepaizi areas.Using a variety of data,methods and techniques,established stratigraphic framework,and studied Sediment source,sedimentary facies type,sedimentary system distribution characteristics and sedimentary evolution rule In the stratigraphic framework,and establishedand the evolution model of sedimentary facies.On this basis,predicted the distribution of favorable reservoirs of the N1s2 of Shawan formation,providing the basis for the optimization of oil and gas exploration targets in this area.Several achievements have been obtained In this thesis as follows:First,by comprehensively using core,mud logging,logging and seismic data,the N1s2 of Shawan formation is divided into 5 sand groups(From bottom to top,S1,S2,S3,S4,S5).And through the plotting of the contour map of stratigraphic thickness,founding the distribution characteristics of the southeast sand and the thin northwest of each sand group.Second,through the analysis of heavy minerals,dip angle and sand body distribution,it is found that the N1s2 of Shawan formation in the study area is the supply of western material source.The parallel tectonic slope break zone is supplied from west to east,redistributive in the eastern part of the study area,and a part continues to move along the slope break zone,and some flow to the depression area in the southeast of the study area.Third,the main development of the N1s2 of Shawan formation in the research area is the meandering river and the meandering river delta,and the meandering river depositional system mainly develops subfacies of river bed,embankment subfacies and river subfacies.Meandering river delta depositional system mainly develops meandering river delta plain and leading edge.Fourth,there are differences in sedimentary facies types and distribution at different periods in the two member of Shahejie formation.In the early stage(S1-S2 sedimentary period),the meandering river facies is developed in the western part of the study area,and the meandering river delta facies is developed in the East.In the late stage(S3-S5 sedimentary period),the study area is a meandering river facies.The river parallel tectonic slope break extends from west to East,and it divides into two rivers in the eastern part of the study area.Fifth,there were found three favorable reservoirs in the N1s2 of Shawan formation,and it is located in Pai 6 wells,Chun 65 wells and wells between Su 1 and Su 3.