西湖凹陷转换断裂发育特征及其油气地质意义  

CHARACTERISTICS OF TRANSFORM FAULTS IN THE XIHU SAG AND THEIR SIGNIFICANCE TO HYDROCARBON ACCUMULATION

作　　者：刘亚茹 高顺莉 周平 唐贤君 LIU Yaru;GAO Shunli;ZHOU Ping;TANG Xianjun(Shanghai Branch of CNOOC China Limited,Shanghai 200335,China)

机构地区：[1]中海石油(中国)有限公司上海分公司,上海200335

出　　处：《海洋地质前沿》2020年第10期42-49,共8页Marine Geology Frontiers

基　　金：“十三五”国家科技重大专项“东海盆地结构和构造演化特征研究”(2016ZX05027-001-001)。

摘　　要：西湖凹陷油气资源丰富,凹陷中部存在大量的挤压反转和转换断裂痕迹,转换断裂对油气的聚集与分布有着密切的关系。基于三维地震资料、重磁场特征及地层厚度,对凹陷内断裂类型和平面剖面特征进行了系统分析,在此基础上识别出3组大型转换断裂带。西湖凹陷平面上主要发育NE-NNE向断裂,主发育期主要位于古新世早期至始新世平湖组沉积期,可分为上、中、下3期断裂体系,转换断裂主要发育在上部断裂体系内。在"南北分区"大背景下,凹陷存在3组主要的大型转换断裂带:舟山-国头转换断裂带、海礁湾南缘转换断裂带和海礁湾北缘转换断裂带。大型转换断裂带对西湖凹陷具有重要的控圈和控藏作用,在其背景下发育多种构造样式和圈闭类型,包括扭动分叉"Y"型圈闭、扭动转换"H"型圈闭和扭动改造"Y"型圈闭等。同时,结合海礁湾南缘转换断裂带上已成藏油气田解剖,分析了转换断裂作为运移通道对油气的二次运移的重要意义。There are many reversed compressional and transform faults in the middle of the Xihu Sag.The transform faults are the ones controlling the accumulation and distribution of oil and gas.Based on 3 D seismic data,gravity data,and stratigraphic thickness changes,the types and distribution patterns of faults in planes and vertical sections are studied in this paper.The sag is dominated by NE-NNE faults formed in the Pinghu stage of early Paleocene to Eocene.The faults may be roughly grouped into three fault systems:upper,middle,and lower,and the transform fault is mainly developed in the upper system.Three groups of transform faults,i.e.the ZhoushanGuotou fault zone,the Southern Haijiao Bay fault zone,and the Northern Haijiao Bay fault zone are identified.Large transform fault zones play significant roles in trap formation and hydrocarbon accumulation.Many types of structures and trap types,such as the twisted and bifurcated"Y"shaped traps,the twisted and transformed"H"shaped traps and the twisted and reformed"Y"shaped traps are mainly developed on the background of the transform fault zone.In combination with the case analysis of oil and gas fields in the transform fault zones of Southern Haijiao Bay,it is concluded that the transform faults,as a migration channel,is of critical significance to the secondary migration of oil and gas.

关 键 词：西湖凹陷 断裂分布 转换断裂 控圈作用 二次运移 

分 类 号：P618.13[天文地球—矿床学]