下刚果-刚果扇盆地油气成藏分析及有利区评价

The Main Control Factor of Hydrocarbon Accumulation and Favorable Area Evaluation in Lower Congo-Congo Fan Basin

下刚果-刚果扇盆地构造演化可划分为裂谷阶段、过渡阶段和被动大陆边缘阶段,发育盐下裂谷期陆相层序、过渡期盐岩层序和盐上被动大陆边缘阶段海相层序,形成盐下裂谷期成藏组合、盐下-盐上复合成藏组合和盐上第三系浊积水道成藏组合。盐下成藏组合主要受控于裂谷盆地的发育和基底隆起,有利区位于陆上盐下裂谷盆地发育区。盐下-盐上复合成藏组合主要受控于盐下烃源岩的规模和盐窗的发育,有利区位于浅海区。盐上第三系浊积水道成藏组合主要受控于第三系浊积砂岩储层的发育及盐上烃源岩的成熟度,有利区位于深水区。

The structural evolution history of Lower Congo-Congo Fan Basin was divided into three phases,such as rifting phase,transitional phase and passive land margin phase.Accordingly three mega sequences of strata were developed: pre-salt rifting continental sequence,transitional evaporative sequence and post-salt passive margin marine sequence.The basin encompassed three kinds of hydrocarbon accumulation modules: pre-salt rifting sequence module,pre-salt-post-salt combined module and post-salt Tertiary module.The three modules had different main controlling factors.The hydrocarbon accumulation of pre-salt sequence module is controlled by the development of rift basins and basement horsts and its favorable area is located in onshore area of the basin.The hydrocarbon accumulation of combined module is controlled by the development of scale of source rock and salt windows and its favorable area is located at shallow water area of the basin.The hydrocarbon accumulation of post-salt module is controlled by the distribution of turbidite sandstone and maturity of source rock and its favorable area is located in deep water area of the basin.