鄂尔多斯盆地镇泾地区延长组异常压力演化及其成藏意义  

The evolution of abnormal pressure of Yanchang Formation in Zhenjing area of Ordos basin and its reservoir-forming significance

作　　者：马立元[1] 邱桂强 李超[2] 王欢[3] 罗源 MA Liyuan;QIU Guiqiang;LI Chao;WANG Huan;LUO Yuan(Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 100083,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;China University of Geosciences,Beijing 100083,China;Engineering Technology Branch of Energy Development Co.,Ltd.,CNOOC,Tianjin 300450,China)

机构地区：[1]中国石油化工股份有限公司石油勘探开发研究院,北京100083 [2]中国科学院地质与地球物理研究所,北京100029 [3]中国地质大学,北京100083 [4]中海油能源发展股份有限公司工程技术分公司,天津300450

出　　处：《地质通报》2020年第4期503-511,共9页Geological Bulletin of China

基　　金：国家科技重大专项《中西部重点碎屑岩层系油气富集规律与勘探方向》(编号:2016ZX05002-006)。

摘　　要：鄂尔多斯盆地南部镇泾探区的主力含油层段为延长组长8油层组,油藏类型为以三角洲前缘分流河道砂岩岩性油藏为主,现今延长组地层压力低、含油饱和度小且变化大,开展地层压力演化研究对认识成藏、富集的动力机制和探区评价均具有重要意义。利用测井声波资料和盆地模拟手段,对长7烃源岩段的地层压力演变过程进行了恢复,分析了异常压力在油气成藏中的动力学意义。结果表明,现今地层压力集中分布在17.99~22.46 MPa,压力系数介于0.8~1.05之间,整体处于常压-负压状态;长7烃源岩段在早白垩世快速埋深,由于欠压实作用,泥岩普遍发育超压,早白垩世末期剩余压力增加到4 MPa左右,压力系数介于1.1~1.3之间,形成低幅超压;晚白垩世以来随着地层抬升,压力逐渐释放并演化为现今压力。在鄂南镇泾地区,延长组储集层致密后,浮力不是油气运移的主要动力,异常压力在油气成藏中起着重要的作用。The Chang 8 group of Upper Triassic Yanchang Formation is the main oil layer in Zhenjing area of southern Ordos basin.The reservoir rock of Chang 8 group is mainly the delta front distributary channel sandstone and its reservoir type is lithology.Low formation pressure,low oil saturation and wide variation range constitute the characteristics of the Chang 8 group reservoir.Research on the evolution of formation pressure is very important for understanding the dynamic mechanism of hydrocarbon accumulation and enrichment.Logging acoustic data calculation and basin numerical simulation were combined to recover the evolution of Chang 7 source rock formation pressure,and the dynamic significance of abnormal pressure in hydrocarbon accumulation was analyzed.The research result shows that the present formation pressure of Mesozoic strata in Zhenjing area is distributed in 17.99 MPa to 22.46 MPa,and the pressure coefficients range from 0.8 to 1.05.The formation is generally in the atmospheric pressure to weak negative pressure state.In Early Cretaceous,the Chang 7 source rock was quickly buried along with the rapid subsidence of basin.Due to the effect of under-compaction and hydrocarbon generation,the mudstone was commonly subjected to overpressure.In the last phase of Early Cretaceous,the overpressure was increased to 4 MPa.The pressure coefficient ranges from 1.1 to 1.3,which means the strata were subjected to small overpressure.Since the Late Cretaceous,with the uplifting of the formation,the pressure has gradually released and evolved into present pressure state.The buoyancy was not the main motive power for hydrocarbon migration after the formation of tight clastic reservoir,and abnormal pressure played an important role in the hydrocarbon accumulation in Zhenjing area of southern Ordos basin.

关 键 词：异常压力 欠压实 成藏动力 延长组 镇泾地区 

分 类 号：P618.13[天文地球—矿床学]