桑托斯盆地西南陆架区盐上地层异常压力与油气运移成藏  

Abnormal pressure and hydrocarbon migration and accumulation in the post-salt formation of southwestern shelf area, Santos Basin

作　　者：赵厚祥 谢东宁 杜宏宇 ZHAO Houxiang;XIE Dongning;DU Hongyu(Block A,CNOOC Building,No.6 Taiyanggong South Street,Chaoyang District,Beijing 100028,China)

机构地区：[1]中海油研究总院

出　　处：《海相油气地质》2019年第4期38-46,共9页Marine Origin Petroleum Geology

基　　金：“十三五”国家科技重大专项课题“西非—南美海域重点区油气地质评价及关键技术研究”（编号：2017ZX05032-001）资助

摘　　要：桑托斯盆地盐上发育巨厚的前三角洲亚相塞诺曼阶—土伦阶Itajai-Acu组海相泥页岩,该套泥页岩处在未熟—成熟阶段,泥页岩及上下围岩存在超压系统。为研究盐上油气富集规律,利用钻井测试压力、测井等资料,分析异常压力形成原因,并研究异常压力与油气运移成藏的规律。研究认为:桑托斯盆地西南陆架区北部超压为成岩作用所致,中部—南部为生烃作用所致;超压层段的上、下超压波及范围内油气运移方式为超压运移,可以形成常规及非常规油气藏;超压运移中,横向运移距离短,垂向运移距离与压差、储层物性以及埋深等因素相关;超压层上部超压波及范围外以浮力运移为主,沟通烃源岩内部的断裂是油气运移通道,在超压层超压波及范围外上部构造高部位形成常规油气藏。超压运移可形成上生下储常规、非常规油气藏,这一认识拓展了勘探空间,为凹陷及斜坡区勘探实践提供了理论指导。The post-salt Itajai-Acu Formation of Cenomanian-Turonian developed a set of thick marine shale of predelta facies in Santos Basin. The source rocks of the shale are in immature to mature stage, and there exist overpressure in the shale and surrounding rocks. Drilling test pressure data and logging data were applied to analysis the causes of abnormal pressure, and to study the regularities of abnormal pressure and hydrocarbon migration. The overpressure in the northern part of southwestern shelf area of Santos Basin was caused by diagenesis, whereas that in middle-south part is caused by hydrocarbon generation. Hydrocarbon migration was driven by overpressure within range of overpressure on or under the overpressure layer, which benefited to form conventional and unconventional reservoirs.The lateral hydrocarbon migration distance was short. The vertical hydrocarbon migration distance is related to pressure difference, reservoir properties, and burial depth. Hydrocarbon migration was driven by buoyancy out range of overpressure on the overpressure layer, which benefited to form conventional oil and gas reservoir in the upper part on the overpressure layer, with fault as hydrocarbon migration channel. This recognition has expanded the exploration space and provided theoretical guidance for the exploration in the depression and slope areas of Santos Basin.

关 键 词：桑托斯盆地 异常压力 生烃作用 成岩作用 超压运移 浮力运移 

分 类 号：TE122.1[石油与天然气工程—油气勘探]