Analysis Of Sedimentary System Of Xingouzui Formation In Central And Southern Part Of Jiangling Sag

This paper selects the Paleogene Xingouzui Formation in central and southern Jiangling Sag of Jianghan basin as the research object.Under the guidance of sequence stratigraphy and sedimentary system theory,through comprehensively absorbing previous research findings and regional regional geological data,this paper utilizes the drill core data,well logging data and seismic data,starts from analysis of lithofacies and lithofacies combination of core well,conducts the analysis of single well sedimentary facies and stratigraphic pattern analysis.Combining with the characteristics of sequence interface,this paper identifies the sequence stratigraphy of different levels in the single well,establishes the sequence stratigraphic framework and conducts the comparison of wells sedimentary facies in sequence stratigraphic framework.Combing with the distribution characteristics analysis of different lithology in different sequence stratigraphic units such as evaporation salt,mudstone and sandstone,this paper clears the distribution and evolution of sedimentary system in the study area in different sequences.This paper focuses on studying the sedimentary system of Xingouzui Formation in central and southern Jiangling Sag,and the results are presented as following:(1)identifies 12 lithofacies such as dark mudstone facies and mixed color mudstone facies and 8 kinds of lithofacies combinations;(2)identifies delta facies,freshwater lacustrine facies and saltwater lacustrine facies in Xingouzui Formation in central and southern Jiangling Sag,and the main sub-facies and micro-facies include lakefront,shallow-lake,shallow-lake sand dam,delta basin distributary channels,delta front subaqueous branch channels and estuary san dam;(3)based on the recognition of sedimentary facies and analysis of characteristics of the seismic emission interface,large flooding surface,logging lithology and lithofacies sign of the main seismic cross-section in the basin,clears the regression-acceleration and acceleration-progradation stratigraphic units,identifies 6 stratigraphic interface of Xingouzui Formation,so as to divide the Xingouzui Formation in the central and southern Jiangling Sag into XSQ1(III Oil Formation and the Mud Layer)and XSQ2(II Oil Formation lower part)XSQ3(II Oil Formation upper part)XSQ4(I Oil Formation)and XSQ5(Xin upper segment);(4)through the comparison of sedimentary facies in wells in the sequence stratigraphic framework,combining the analysis of characteristics of different seismic reflection and distribution of seismic facies and the analysis of the data about mudstone thickness,reduced color mudstone thickness,sandstone thickness,percentage of sandstone and thickness of evaporating rock in different stratigraphy sequence,clears the distribution and change process of sedimentary facies in each sequence;thereby formulating the sedimentary model of Xingouzui Formation in central and southern Jiangling Sag.