下刚果—刚果扇盆地断裂特征及其对油气成藏的影响

下刚果—刚果扇盆地油气资源丰富、油气成藏条件优越。但由于受到盐岩的活动及区域构造应力场的作用,形成了复杂的断裂系统。此文系统分析了下刚果—刚果扇盆地的断裂特征及其对油气成藏的影响,研究认为该区平面上主要发育5个断裂带,纵向上主要发育上下两套断裂系统。断裂的形成和演化可分为三个期次,相对应可将断层分为三个级别的断层。断层的形成机制主要有盐活动及盐构造、重力滑脱作用以及古地貌格局。烃源岩的排烃时间与第三期断层活动时间相匹配,非常有利于油气沿断层进行垂向和斜侧向运移。分析认为研究区主要发育沿断阶带—碳酸盐岩运聚成藏模式、沿断层垂向运聚成藏模式以及沿盐下砂体—盐窗和Focus点运聚成藏模式共三种成藏模式。断层封堵较好,油源断层高度决定了油气运移高度和油气田规模,直接控制着油气的分布层系及规模。研究成果可指导研究区或类似地区的油气勘探。

The Fracture Characteristics and Its Impacts on Hydrocarbon Accumulation in Lower Congo Basin and Congo Fan Basin

Hydrocarbon resources are rich and hydrocarbon accumulation is good in Lower Congo Basin and Congo Fan Basin. Because of the salt movements and the influence of regional tectonic stress field, fault systems are very complex. Fracture characteristics and hydrocarbon accumulation in Lower Congo Basin and Congo Fan Basin was analyzed in this article. The results show that there are 5 fault belts in lateral and 2 fault systems in longitudinal. The formation and evolution can be divided into 3 stages, and the forming mechanism of faults primarily includes salt movement and salt tectonic, gravity gliding mechanism and palaeogeomorphology framework. Expelling hydrocarbon period matches fault movement period and it＇s propitious to vertical and parallel migration of hydrocarbon, and there are mainly 3 kinds of hydrocarbon accumulation models. The fault seal is very good, and the height of oil source faults controls the height of hydrocarbon migration and the field scale. This study can be used to guide the exploration in this area and other similar areas.