川中—川南过渡带须家河组二段沉积相研究

Sedimentary facies of the second member of Xujiahe Formation in the central-southern
Sichuan transitional zone

刘建锋 彭 军 张连进 徐明华 陈 果 郭双生

西南石油大学资源与环境学院，四川 成都 610500 川庆钻探工程公司地质勘探开发研究院，四川 成都 610051 中国石油西部钻探测井公司，新疆 克拉玛依 834000

College of Resources and Environment, Southwest Petroleum University,Chengdu 610500, China Geological Exploration and Development Research Institute, Chuan-Qing Drilling Engineering Company, Chengdu 610500, China Logging Company, Western Drilling and Exploration Company, CNPC, Karamay 834000, China

在了解区域沉积背景的情况下，通过对大量野外剖面观察、地震剖面资料、测井资料、取心井段和单井沉积微相研究的基础上，确定了研究区须家河组二段为河流三角洲－湖泊沉积体系，主要发育三角洲前缘、前三角洲、浅湖3种沉积亚相。三角洲前缘亚相以水下分流河道微相占优势，先期形成的河口坝往往受后期水下分流河道冲刷侵蚀而得不到完整保存，所以须家河组二段河口坝不甚发育，在剖面上水下分流河道与河口坝多呈冲刷截切叠置关系。

Based on the understanding of background of regional sedimentation, observing for large amount of drilling, coring and field section plane, analyzing for seismic data, logging information, as well as the study on the sedimentary microfacies of coring section and single well, it is determined that the region of interest of the second member of Xujiahe Formation is formed in a sedimentary system of river delta to lake. Three subfacies have been mainly developed, which are deltafront, prodelta and shallow lake. The deltafront subfaceies is dominantly of underwater distributary channel. The pre-formed mouth bars are not preserved completely because of the erosion by the underwater distributary channel that formed latter, so the
mouth bar in the second member of Xujiahe Formation is not well developed. Underwater distributary channel and mouth bar are often in relations of flushing, intercepting and overlaying in the section.