High-resolution Sequence Stratigraphy for Fan Delta at Steep Slope Belt: Taking the Lower Sand Groups of the Third-submember Sedimentation of MemberIII of Shahejie Formation in the North Region of Liuzan Oilfield as an Example

Based on the detailed analysis of sedimentary facies features of fan delta,core,logging and seismic data are used to perform detailed high resolution sequence stratigraphy analysis of the lower sand groups of the third-submember sedimentation of MemberⅢ of Shahejie Formation in the north region of LiuZan Oilfield.The results show that progradational fan delta is well developed in the research area.Fan deltas there can be subdivided into three subfacies and six microfacies,showing coarsening upward succession.Based on the recognition of various grades of base-level cycles,high-resolution sequence stratigraphic framework is built.Geometric features and distribution pattern of the reservoir sand bodies of fan delta in stratigraphic framework are significantly controlled by A/S ratios in medium-term base level cycles and ancient landform.The study result has guiding significance for stratigraphic correlation and well pattern adjustment in middle and later period of oilfield development.