Sedimentary Facies And Reservoir Characteristics Of The Shahejie Formation In The #43 Well Area Of The South Slope Of Guojuzi Subsag

The research area is structurally located on the south slope of Guojuzi Depression in the eastern Aoxianche town of Jiyang.The area is surrounded by Sikou depression and Shaojia depression and Yihezhuang salient,which is with low exploration extent,there's large oil and gas potential here with high exploration value.Since there are few test data regarding to drilling,paleontology,and others in the research area,thus 3D seismic data are fully used based on existing core and drilling well logging data to clarify the tectonic evolution rules and establish Sha-4 isochron sequence stratum in the entire area,thus to further expound the study on the type of development of the sedimentation phase,spread,reservoir characteristics,and favorable reservoir control factors.The author in this paper conducted the repeat comparison of sequence stratum by integrating with lithologic map,well Logging and seismic data,combined with the sequence interface characteristics,the author believed that Kongdian Group should not be developed on the south slope of Guojuzi depression,and Sha-4 was over the Mesozoic buried hill directly.The three-level sequence in the 4^th Member of Shahejie section can be further divided into the 4^th Member of Shahejie upper sequence and Sha-4 lower sequence;the four-level sequence is divided into Sha-4 upper high field,and Sha-4 upper lake invaded area,and Sha-4lower high field and eight five-level sequence interfaces.In the isochronous sequence stratum framework,the original geomorphic morphology of Sha-4 stratum on the southern slope of Guojuzi Depression was restored based on characteristics of tectonic spreading and evolution rules.The analytic means such as the ancient geomorphology research,ancient channel identification and others to identify the physical source area,based on this,the author divided the sedimentary phase of the research area into three types of sedimentary phase:fan delta,alluvial fan,and lacustrine phase by combining with the single well phase,seismic facies and multi-attribute analysis results.The reservoir lithologic map on the southern slope of Sha-4 of Guojuzi Depression mainly contains glutenite and sandstone,and reservoir diagenesis mainly includes compaction,cementation and corrosion.The pore type is dominated by the secondary pores,which are distributed unevenly with different sizes.The favorable sands in the research area are distributed in the fans of the alluvial fan and the subfacies of the front of the fan delta.The area with high value of thickness and percentage shows banding,fanned,and crumby distributions,which are thinned towards the fan-edge position.The controlling factors of comprehensive sedimentation,diagenesis,tectonic and acid containing liquid sources are the favorable reservoir.Main oil source comes from Sikou depression,different sedimentation subfacies have obvious physical property differences of the reservoir,which is mainly distributed in fan of alluvial fan and front subfacies of the fanned delta.It's found that the fractures on the eastern side of the work area had undergone a significant expansion.The fault was first subjected to a levorotation stress and then was subjected to a dextrorotation stress,which promoted the formation of favorable reservoir.