塞内加尔盆地演化过程与岩性油气藏勘探前景  

Evolution of Senegal Basin and exploration prospects of lithologic reservoirs

作　　者：李恒萱 温志新[1] 宋成鹏[1] 刘祚冬[1] 季天愚 沈一平 耿珂 LI Hengxuan;WEN Zhixin;SONG Chengpeng;LIU Zuodong;JI Tianyu;SHEN Yiping;GENG Ke(PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China)

机构地区：[1]中国石油勘探开发研究院,北京100083

出　　处：《岩性油气藏》2023年第6期45-53,共9页Lithologic Reservoirs

基　　金：中国石油天然气集团有限公司基础性前瞻性科技专项“海外油气地质新理论资源评价新技术与超前选区研究”(编号:2023ZZ07)及“基于多重地质属性溯源定位的全球六类盆地油气成藏规律研究”(编号:2023ZZ0701)联合资助

摘　　要：被动大陆边缘盆地勘探程度低、潜力大,塞内加尔盆地是近年来被动陆缘勘探的热点地区之一。基于板块学说,利用地震、地质等资料,恢复了塞内加尔盆地的演化过程,并展望了其岩性油气藏勘探前景。研究结果表明:①塞内加尔盆地可划分为3个演化阶段,中三叠世裂陷期陆内裂谷盆地、晚三叠世—早侏罗世过渡期陆间裂谷盆地、中侏罗世至今漂移期被动陆缘盆地。受古构造和古气候的控制,裂谷层系较薄,且埋藏深,以陆相红色地层为主;陆间裂谷期广泛发育蒸发岩相;漂移期坳陷层序沉积厚度大,深水沉积体系是目前已发现油气田的重要储集层。②中部次盆深水区主要发育下白垩统阿尔布阶三角洲砂体,油气侧向或垂向运移形成下白垩统断层-岩性复合油气藏;超深水区发育上白垩统塞诺曼阶-马斯特里赫特阶浊积扇砂体,下部油气向上运移形成上白垩统海底扇岩性油气藏;毛里塔尼亚和卡萨芒斯盐盆主要发育中新统浊积扇砂体,盐底辟对油气运移和封闭具有重要影响,可形成与盐构造相关的油气藏。③通过已发现油气藏的成藏规律可预测尚未钻井的毛里塔尼亚、卡萨芒斯次盆可能也发育上白垩统海底扇岩性油气藏,且整个盆地陆架碳酸盐岩台地存在礁滩体油气藏,为下一步重点勘探领域。Passive continental margin basins have low exploration degree and high potential,and Senegal Basin is one of the exploration hotspots of passive continental margin basins in recent years.Based on plate tectonic evolution,the evolution process of Senegal Basin was restored using seismic and geologic data,and the exploration prospects of lithologic reservoirs were analyzed.The results show that:(1)The Senegal Basin can be divided into three evolution stages,incluing intra-continental rift during the Middle Triassic rift,inter-continental rift during the Late Triassic to Early Jurassic transition,and passive continental margin during the Middle Jurassic to the present drift.Controlled by paleostructure and paleoclimate,the rift sediments are thin and buried deeply,mainly in continental red beds stratigraphic sequence.Evaporite facies develop widely in inter continental rift.The drifting sequence deposits with large thickness and deep-water sedimentary system are important reservoirs in discovered oil and gas fields.(2)The Lower Cretaceous Albian delta sand bodies were mainly developed in the deep-water area of the Middle sub-basin,and the Lower Cretaceous fault-lithologic reservoirs were formed by lateral or vertical migration of oil and gas.The Upper Cretaceous Cenomanian-Maastrichtian turbidity fan sand bodies were developed in the ultra-deep water area,and the oil and gas migrated upward to form Upper Cretaceous submarine fan lithologic reservoirs.Miocene turbidite fan sand bodies were mainly developed in Mauritania and Casamance salt basins,salt diapirs have important effects on oil and gas migration and sealing,forming salt structure related oil and gas reservoirs.(3)Combined with the discovered law of oil and gas accumulation,the Upper Cretaceous submarine fan reservoirs may be developed in Mauritania and Casamance subbasins without drilled wells,while the reef-shoal reservoirs may be developed in the carbonate platform of the entire basin shelf,and they are the next key exploration areas.

关 键 词：岩性油气藏 原型盆地 陆内裂谷盆地 陆间裂谷盆地 被动大陆边缘盆地 深水沉积 海底扇 浊积扇 礁滩体 塞内加尔盆地 

分 类 号：TE121.11[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]