北加蓬次盆油气成藏主控因素分析及勘探潜力评价

Main controlling factors and exploration potential of hydrocarbon reservoirs in North Gabon sub-Basin

北加蓬次盆是一个裂谷盆地与被动大陆边缘盆地叠加形成的中、新生代复合盆地,油气成藏明显受构造运动、沉积环境、盐岩变形等地质因素的控制。盆地东部因抬升剥蚀而遭受不同程度的破坏,烃源岩及油气藏没有很好地保存,导致了东部构造带和西部构造带油气资源贫富差异较大。沉积环境影响储层发育,上白垩统浊积扇砂体和三角洲砂体是盐上层系最重要的储层,油气圈闭的形成与盐岩构造活动密切相关,圈闭类型丰富多彩。根据盐上层系烃源岩和浊积砂体储层分布等地质规律研究,北加蓬次盆大西洋深水斜坡带的中南部处于Azile组主力烃源岩分布区,油气源供给条件优越,储层发育,油气成藏条件得天独厚,是盆地油气勘探最有利的地区。

The North Gabon sub-Basin is a Mesozoic- Cenozoic rift and divergent margin basin. The oil and gas reservoirs in the basin were controlled by tectonic movements,sedimentary environments and salt structures. The east of the basin was eroded due to regional uplift,and source rocks and hydrocarbon reservoirs were destroyed,leading to a significant difference of hydrocarbon potential between the east and the west tectonic belts. Sedimentary environments impacted reservoirs. The Upper Cretaceous turbidity sandstones and offshore sandstones were important reservoirs for the post salt layers. Various traps developed,which were related to salt structure activities. Based on research of the turbidity sandstones and offshore sandstones of the post-salt layers,the main hydrocarbon reservoirs of the North Gabon sub-Basin mainly lie on the middle-south,deep ocean slope belt,which is the center of the major source rocks of the Azile Formation. Thanks to favorable sourcing and reserving conditions,the middle-south,deep ocean slope belthas considerable hydrocarbon prospects.