西非里奥穆尼盆地油气成藏条件及勘探方向

西非里奥穆尼盆地经历了陆内裂谷、陆间裂谷和被动大陆边缘3个构造演化阶段,发育多套烃源岩、储层及泥页岩(盐岩)盖层。以陆间裂谷阶段发育的阿普特盐岩层为界,主要形成盐上、盐下2大含油气系统。盐构造、有利储层控制了盐上含油气系统的有效成藏,优质烃源、盖层则为盐下含油气系统的关键成藏要素。综合分析认为,里奥穆尼盆地的油气勘探重点为盐上的白垩系,应寻找与盐构造相关、浊积砂体发育的构造—地层复合型油气藏;对盐下领域,应重点探索裂谷洼陷生烃中心、阿普特盐岩封盖条件好的地区,并以近源的有利构造作为优先勘探目标。

Petroleum accumulation conditions and exploration direction of Rio Muni Basin,West Africa

Based on the background of regional structural evolution, the tectono-sedimentary evolution of Rio Muni Basin, West Africa can be divided into three phases: intracontinental rift, intercontinental rift and passive continental margin. It has been proved by exploration and research that there are multilayer source rocks, reservoirs and caps in the basin. With the Aptian Salt developed in the intracontinental rift phase as the interface, there are pre-salt and post-salt petroleum systems. It is showed that salt structures and favorable reservoirs control the effective hydrocarbon accumulation of the post-salt system, while high-quality source rocks and caps are the key reservoir forming factors of the pre-salt system. It is recognized by comprehensive analysis that the petroleum exploration focus should be the Cretaceous on the salt and the complex hydrocarbon reservoirs with structure stratigraphy with the development of salt structure and turbidite sand body. It is suggested that the near-source favorable structures are priority exploration targets to the pre-salt strata in the area located in the hydrocarbon generation center of rift sag.