西非塞拉利昂—利比里亚盆地深水岩性油气藏成藏特征

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英文篇名：GEOLOGICAL CHARACTERISTICS OF OIL AND GAS ACCUMULATIONS IN THE SIERRA SIERRA LEONE-LIBERIA BASIN,WEST AFRICA 作者：孔令武 ; 赵红岩 ; 赵佳奇 ; 陈亮 ; 喻英梅 ; 李任远 英文作者：KONG Lingwu;ZHAO Hongyan;ZHAO Jiaqi;CHEN Liang;YU Yingmei;LI Renyuan;CNOOC Research Institute; 关键词：构造演化 ; 烃源岩 ; 深水沉积体 ; 成藏模式 ; 岩性油气藏 ; 勘探方向 英文关键词：tectonic evolution;;source rock;;deep-water sediment bodies;;accumulation model;;lithologic reservoirs;;exploration direction 中文刊名：HYDT 英文刊名：Marine Geology Frontiers 机构：中海油研究总院; 出版日期：2018-11-22 出版单位：海洋地质前沿 年：2018 期：v.34;No.432 基金：国家科技重大专项“非洲重点区油气勘探潜力综合评价(2017ZX05032-002) 语种：中文; 页：HYDT201811004 页数：7 CN：11 ISSN：37-1475/P 分类号：29-35

摘要

立足于大西洋的构造演化,划分了盆地构造演化阶段,明确了不同演化阶段的构造、沉积特征,分析了漂移期岩性油气藏的成藏特征,建立油气成藏模式,指出了油气勘探的方向。研究表明,塞拉利昂—利比里亚盆地经历了裂陷期和漂移期两个演化阶段,早白垩世裂陷期,构造活动强烈,以陆相沉积为主;晚白垩世至今的漂移期构造活动弱,以海相沉积为主。赛诺曼—土伦阶海相烃源岩是漂移期岩性油气藏的主要油气来源,是油气成藏的基础;盆地漂移期广泛发育大型深水沉积体,深水沉积体是漂移期储层和岩性圈闭形成的关键;油气运移控制了岩性油气藏的成藏模式,漂移期构造活动弱,缺少油源断裂,赛诺曼—土伦阶成熟烃源岩生成的油气就近运移至烃源岩层内的岩性圈闭中聚集成藏,形成自生自储的油气成藏模式;寻找赛诺曼—土伦阶烃源岩灶内大型沉积体是盆地未来深水区油气勘探的重要方向。
        With reference to the tectonic evolution of the Atlantic,we studied the oil and gas geological characteristics of the Sierra Sierra Leone-Liberia Basin.Results show that the Sierra Leone-Liberia Basin has experienced two stages of tectonic evolution,i.e.the rifting stage and drifting stage.Hydrocarbon is mainly accumulated in the lithologic reservoirs formed during the drifting stage.A hydrocarbon accumulation model is then established for clarification of exploration directions based upon the above observation.During the Early Cretaceous of the rifting stage,tectonic activity was strong in the basin and thus the basin was dominated by continental deposits,while during the Late Cretaceous to present of the drifting stage,tectonic activity was weak and marine sediments dominated.The Cenmanian-Turonian marine source rock is the major source of the lithologically trapped oil and gas resources.Large-scale deep-water sediment bodies,which are critical important to the formation of oil and gas reservoirs and lithologic traps,are widely formed during the drifting stage.The hydrocarbon generated in the matured Cenomanian-Turonian source rock has no way but migrating into the lithologic trap within the source rock sequence itself to form a kind of self-generated and self-accumulated oil and gas reservoirs since tectonic movement was weak and there was lacking of fractures.To look for large-scale deep-water sediment bodies in the source kitchen is one of the important exploration directions in the future in deepwater areas.

引文

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