摘要
本文利用高精度三维地震、钻井等资料,对涠西南凹陷主要断裂发育特征及演化进行解析,并结合区域应力场,分析断裂成因机制,进而探讨断裂对油气成藏的影响。研究结果表明,主要断裂的构造样式和活动特征存在明显差异。其中,F_(1)和F_(3)断裂的NEE向区段古近纪以低角度伸展为主,控制了古近纪断陷的沉降和充填,而其NE向区段则在新近纪初期开始高角度差异升降活动,并对古近系造成不同程度的改造;F_(2)断裂中段主要活动期为始新世,而西段主要形成于渐新世涠洲组沉积期、早中新世再次活动。受太平洋板块、欧亚板块、印度板块相互作用产生的伸展-走滑应力场叠加作用,涠西南凹陷在先存构造条件下,形成了NE向、NNE向、近EW向及NW向等断裂体系。应力场方向右行旋转导致/强化F_(1)、F_(2)、F_(3)断裂的差异活动。F_(1)和F_(2)断裂形成演化控制涠西南凹陷流沙港组烃源岩的发育与分布,油源断层垂向输导、砂体/不整合-断层复合输导等主要运移方式对该区油气的成藏与分布起着重要的作用。
Using high-precision 3D seismic and drilling data,the development characteristics,evolution,and genetic mechanism of the main faults in the Weixinan Sag were analyzed,and the influence of these faults on petroleum accumulation were discussed in this paper.The results showed that there were obvious differences in the structural styles and activity characteristics of the main faults,among which the NEE-trending sections of the F_(1)and F_(3)faults were a low-angle extensional fault that controlled the subsidence and filling of the sag during the Paleogene,while their NE-trending section was a high-angle differential uplift fault formed in the Early Neogene,which deformed the Paleogene sediments.The middle section of the F_(2)fault was mainly active in the Eocene,while its western section was principally formed during the sedimentary period of the Weizhou Formation in the Oligocene and re-actived in the Early Miocene.Under the superposition of the extension-strike-slip stress fields caused by the interaction of the Pacific,Eurasian,and India Plates,the Weixinan Sag,based on pre-existing tectonic conditions,developed the fracture systems of NE,NNE,nearly EW,and NW directions,and the dextral rotation of the stress field direction led to the differential activity of F_(1),F_(2),and F_(3)faults.The formation and evolution of the F_(1)and F_(2)faults controlled the thickness and distribution of the Liushagang Formation source rocks.The two main hydrocarbon migration patterns(the vertical transport of oil-source faults and the composite transport of sand body/unconformity-fault)are two critical factors controlling the accumulation and distribution of oil and gas in the Weixinan Sag.
作者
张毅
毛宁波
何丽娟
黄灏
ZHANG Yi;MAO Ningbo;HE Lijuan;HUANG Hao(School of Geophysics and Oil Resources,Yangtze University,Wuhan 430100,Hubei,China;CNOOC International Limited,Beijing 100010,China;CNOOC Limited,Beijing 100010,China)
出处
《大地构造与成矿学》
北大核心
2025年第4期912-924,共13页
Geotectonica et Metallogenia
基金
中国海洋石油有限公司“十四五”科技重大专项(KJGG2022-0303)资助。
关键词
北部湾盆地
涠西南凹陷
主要断裂
构造样式
差异演化
油气成藏
Beibu Gulf Basin
Weixinan Sag
major faults
structural styles
differential activity
oil and gas accumulation
