【作者】 郑应钊；

【导师】 何登发；

【作者基本信息】 中国地质大学(北京) ， 能源地质工程， 2012， 博士

【摘要】 西非海岸盆地带是油气富集区，是当今国际油气勘探开发的热点地区。本论文以西非54个大油气田资料为基础，结合西非海岸盆地的构造沉积演化过程，应用含油气系统的研究思路和方法，详细分析了五个重点盆地的烃源岩、储集层、盖层、圈闭、油气运移等成藏要素，对大油气田进行了解剖，总结其成藏主控因素；最终划分了西非海岸盆地带的四套主要含油气系统，并参考盆地油气资源量分析了各盆地的勘探潜力。通过本次研究，论文取得了5个方面的认识和进展：1)、以St Paul断裂带和Walvis Ridge隆起带为界，将西非海岸盆地带划分为三段：北段、中段和南段。北段盆地的演化主要经历了前裂谷期、裂谷期和被动大陆边缘三个主要时期；中南段盆地的演化经历了前裂谷期、裂谷期、过渡期和漂移期四个阶段。2）、西非海岸盆地带主要有四套含油气系统：Akata组-Agbada组含油气系统、上白垩统-新生界含油气系统、下白垩统-上白垩统含油气系统、下白垩统-下白垩统含油气系统。3）、西非海岸盆地带共发现54个大油气田，可采油当量为52225MMB。①大油气田主要分布于尼日尔三角洲盆地和下刚果盆地。储层岩性主要为砂岩，其次为碳酸盐岩；产油层系以古近系、新近系为主,其次为白垩系。②北段盆地尚未发现大油气田。中段的下刚果和加蓬海岸盆地，只发现了大油田。在尼日尔三角洲盆地，发现了24个大油田，9个大气田。在西南非海岸盆地，发现了2个大气田。4）、在尼日尔三角洲盆地，油气藏圈闭以构造圈闭为主，油气田的形成主要受滚动背斜构造带的控制。过渡阶段的蒸发盐层序在油气生成、运移和成藏过程中起着重要作用；在下刚果盆地，盐下白垩系油气成藏的主控因素是圈闭；盐上白垩系油气成藏及分布的主控因素是圈闭和储层。盐上古近系油气成藏的主控因素是烃源岩成熟度、圈闭条件。5）、北段沉积盆地众多，面积大，勘探程度低，有勘探潜力。中段盆地油气成藏条件优越，发现了较多大油气田，深水区具有较大的勘探前景。南段盆地的油气发现主要位于奥兰治次盆，勘探潜力一般。更多还原

【Abstract】 The coastal basins in West Africa are petroliferous basins in theworld; also they are one of the key areas of international oil and gasexploretion and production. In this paper, based on the data of 54 giantoil and gas fields, combining the tectonic-sedimentary evolution of thesebasins, applying the research clue and method of petroleum systems,closely analyzes the play elements, incloding the source rocks,reservoirs and seals, traps and the migration of oil and gas.Throughdissecting the typical giant oil or gas fields,finally classified andassessed the petroleum system in these Basins,and finally analyzed theexploring potentials of these basins.The research results are as follows:1) The coastal basins were divided into northern section, middlesection and southern section by St. Paul fault and Walvis Ridge. Thenorthern section basins experienced pre-rift stage, rift stage andpassive continental margin stage. The middle and southern section basinsexperienced pre-rift stage, rift stage, transition stage and passivecontinental margin stage.2) 4 sets of petroleum systems had been set up in the coastal basinsof West Africa: Akata-agbada petroleum system, Upper Cretaceous-Cenozoicpetroleum system, Lower Cretaceous- Upper Cretaceous petroleum system,Lower Cretaceous- Lower Cretaceous petroleum system.3) By the end of 2009, 54 giant oil and gas fields have been foundin the coastal basins in West Africa, with 52224.75MMBOE.The giant oiland gas fields are formed and distributed in the following rules:①Thegiant oil and gas fields are abundantly distributed in Niger delta basinand Lower Congo basin along the coast. The reservoir racks are mainlysandstone and carbonate, the reservoir formation belong to Tertiary orCretaceous.②In the northern section，neither giant oilfield nor gas field had been found.In the middle section,such as such as Lower Congobasin and Gabon basin, only several giant oil fields had been found; Whilein Niger delta basin, 9 giant gas fields and 24 giant oil fields had beenfound; In the southern section,Only 2 giant gas fields had been found.4) In Niger delta basin, the reservoir traps are predominatelystructural traps, the forming of the giant oil and gas fields is mainlycontrolled by the rollover anticline. The deposition of salt rocks hasa crucial effect to the oil and gas generation, immigration, andaccumulation.In Lower Congo basin, the controlling factors for theunder-salt cretaceous reservoir is traps; For the upper-salt cretaceousreservoirs, the controlling factors are traps and reservoirs; For thetertiary reservoirs, the main controlling factors are traps and thematurity of the source rocks.5) The northern section although include several huge sedimentarybasins, it experienced low exploration activity and has little chance tofind giant fields. In the middle section, the basins have excellentreservoir-forming conditions. In the southern section, exploration canbe carry on in Orange Sub-basin.In the future，the exploration can focuson the middle section, especially on the turbidite reservoirs in deepwater zone.更多还原