巴西桑托斯盆地构造演化与油气勘探前景  

TECTONIC EVOLUTION OF SANTOS BASIN,BRAZIL AND ITS BEARING ON OIL-GAS EXPLORATION

作　　者：孙旭东 郑求根[2] 郭兴伟[1] 温珍河[1] 张训华[1] 王锦洲 栗杰 李子渊 SUN Xudong;ZHENG Qiugen;GUO Xingwei;WEN Zhenhe;ZHANG Xunhua;WANG Jinzhou;LI Jie;LI Ziyuan(Qingdao Institute of Marine Geology,China Geological Survey,Qingdao 266071,China;School of Ocean Sciences,China University of Geosciences(Beijing),Beijing 100083,China;Petrochina Southwest Oil&Gas field Company,Chengdu 610000,China)

机构地区：[1]中国地质调查局青岛海洋地质研究所,青岛266071 [2]中国地质大学(北京)海洋学院,北京100083 [3]中国石油西南油气田分公司,成都610000

出　　处：《海洋地质前沿》2021年第2期37-45,共9页Marine Geology Frontiers

基　　金：“十三五”国家科技重大专项(2016ZX05033-001-001);国家自然科学基金(41776081,91958210);中国地质调查局地质调查项目(DD20190429,DD20190365,DD 20190377)。

摘　　要：位于巴西东岸的南大西洋被动大陆边缘盆地−桑托斯盆地是我国海外油气勘探的重要区块。通过地震资料分析,结合叠合盆地演化原理以及南大西洋演化历程,将桑托斯盆地的构造演化阶段划分为前裂谷期、裂谷期、过渡期、漂移期4个阶段,对应克拉通、裂谷、坳陷、被动大陆边缘4类原型盆地。原型盆地的时空匹配关系为桑托斯盆地形成超大型的含油气系统提供了极为理想的构造条件。结合前人的研究成果对盆地“生储盖”组合分析,得出桑托斯油气富集成藏的规律,即“厚盐区盐下富集;薄盐区盐上富集”。通过对盆地区域构造史以及所得的地震资料分析,认为在目前重视不足的盐下东部坳陷地区存在厚层优质的湖相烃源岩,烃类沿着基底大断裂以及不整合面运移,被过渡期蒸发盐岩所阻挡,形成以构造-地层复合圈闭和地层不整合遮挡圈闭为主的油气藏。The Santos Basin,a passive continental margin basin in the South Atlantic Ocean on the east coast of Brazil,is an important target for oil-gas exploration for the time being.Based on the interpretation of seismic data,combined with the evolutionary model of a superimposed basin for the South Atlantic Ocean,the tectonic evolution of the Santos Basin can be subdivided into four stages:pre rifting stage,rifting stage,transitional stage and drifting stage,corresponding to the four prototype basins of craton,rift,depression,and passive continental margin.The well-matched spatiotemporal relationship of the prototype basin provides ideal tectonic conditions for the generation of super large oil-gas systems in the Santos Basin.Based on the previous research results on the"source-reservoir-cap system",the oil-gas distribution patterns are clear,that is,"accumulated under salt in the area with thick salt;and above the salt in the area with thin salt".The analysis of regional tectonic evolutionary history of the basin with seismic data has revealed that there are thick and high-quality lacustrine source rocks in the neglected eastern depression area under salt,oil and gas generated may migrate following the major basement faults and unconformities.Blocked by the evaporite rocks deposited in the transitional period,oil-gas accumulations are dominantly formed in the composite structural and stratigraphic traps and stratigraphic unconformity blocked traps.

关 键 词：桑托斯盆地 共轭盆地 油气成藏 东部坳陷区块 

分 类 号：P618.13[天文地球—矿床学] P744.4[天文地球—地质学]