| The paper mainly studies Sha-1 member on the southern slope of Dongying Sag.Comprehensive analysis of cores,logging,and seismic data reveals the sequence stratigraphy of Sha-1 member.The study concluded that the Sha-1 member of the Shahejie Formation on the southern slope of Dongying Sag can be viewed as a 3-order sequence,which is named as SQs1,and can be subdivided into lacustrine transgressive system tract and lacustrine retreat system tract.The sequence-stratigraphy model is obviously controlled by lake level lifting and source supply.During the sedimentation of Sha-1 member,the geological structure was stable with small paleotopographic gradient(0.52°~1.29° in the east section,0.5°~1.8° in the west section).The climate was comparatively humid with basin water ranging from 9.2m to 52 m.The braided river delta with large distribution area are mainly developed in the east section.The descending plate of the Gaoqing fault in the west section mainly develops small fan delta with large front edge.According to the development regularity of sedimentary facies belt,it is predicted that the favorable sand bodies are distributary channel sand bodies in braided river delta and beach bar sand bodies at the front of fans,which lays a geological foundation for guiding subsequent oil and gas exploration. |
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