琼东南盆地断阶带地貌控制下的辫状河三角洲发育特征——以宝岛凹陷北坡渐新统陵水组三段为例  

Development characteristics of braided river delta under geomorphic control of fault step zone in Qiongdongnan Basin:taking the 3rd member of Oligocene Lingshui Formation in the northern slope of Baodao Sag as an example

作　　者：邓孝亮 汪紫菱 尤丽 詹冶萍 周晨 DENG Xiaoliang;WANG Ziling;YOU Li;ZHAN Yeping;ZHOU Chen(Hainan Branch of CNOOC China Limited;Zhanjiang Branch of CNOOC China Limited)

机构地区：[1]中海石油(中国)有限公司海南分公司,海南省海口市570312 [2]中海石油(中国)有限公司湛江分公司

出　　处：《海相油气地质》2025年第1期30-40,共11页Marine Origin Petroleum Geology

基　　金：中海石油(中国)有限公司科技项目“南海大中型天然气田形成条件、勘探潜力与突破方向”(编号:KJZH-2021-0003-00);中国海洋石油集团有限公司“十四五”重大科技项目“南海北部深水区勘探关键技术”(编号:KJGG2021-0100);海南省“南海新星”科技创新人才平台项目“宝岛凹陷东南缘超深水天然气优质储层识别及成藏机理研究”(编号:NHXXRCXM202367)联合资助。

摘　　要：琼东南盆地深层渐新统陵水组是南海海域下一步勘探的重点。基于岩心、测录井和三维地震资料,系统解剖了琼东南盆地宝岛凹陷北部陵水组沉积特征,明确陵水组可细分为2个三级层序,其中陵三段沉积为一个完整的三级层序,发育低位、海侵和高位体系域。控凹的F12断层差异活动形成的断层同向转换带以及转换斜坡控制着神狐隆起和海南隆起物源的注入,并控制了陵三段规模各异的西、东多支大型辨状河三角洲群的发育。断阶带在低位晚期和高位期主要发育辫状河三角洲前缘水下分流河道沉积,砂体厚度大,粒度较粗,分选较好,物性较好,为优质储层发育层段。由此建立宝岛凹陷北部断阶带陵三段深水盆地多级断裂控物源,转换断阶控砂体展布的发育模式。陵三段大型三角洲前缘水下分流河道优质储集体直接覆盖于崖城组烃源岩之上,与沟通烃源岩的断裂形成有利输导体系,又被后期拗陷期沉积的厚层海侵浅海泥岩覆盖,形成的优质储盖组合和输导体系是形成宝岛凹陷大型气田的关键。Qiongdongnan Basin,a passive continental deep-water basin in the north of the South China Sea,is an important natural gas base in China.The deep Oligocene Lingshui Formation in Qiongdongnan Basin represent a primary target for forthcoming exploration in the South China Sea,however,due to limited exploration efforts,the sedimentary system of the Lingshui Formation remains inadequately characterized.Based on core,logging and 3D seismic data,the sedimentary characteristics of Lingshui Formation in northern slope of Baodao Sag,Qiongdongnan Basin are systematically dissected.It is clear that Lingshui Formation can be subdivided into two third-order sequences.The sedimentation of the 3rd member of Lingshui Formation is a complete three-order sequence with low,transgressive and high system domains.Under the control of the fault co directional transition zone and transition slope formed by the differential activity of F12 fault,several large differentiated river delta groups of different scales in the west and east are developed in the 3rd member of Lingshui Formation.The fault step zone mainly developed the underwater distributary channel of braided river delta front in the late low and high system tracts,and it is a high-quality reservoir development interval with the thickness of sand body being large,the particle size being coarser,the separation being better,and the physical property being better.Therefore,the development model of multistage fault-controlled material source and transition fault-controlled sand body distribution of the 3rd member of Lingshui Formation in the northern fault step zone of Baodao Sag is established.The high quality reservoir of large-scale delta distributary channel of the 3rd member of Lingshui Formation directly covers the source rock of Yacheng Formation and forms a favorable transport system with source rock-linked fault.And it is covered by thick transgressive shallow-sea mudstone deposited in late depression period.High-quality reservoer-cap combination and transport system are the

关 键 词：辫状河三角洲 断阶带 陵水组三段 古近系 宝岛凹陷 琼东南盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]