全球被动陆缘盆地构造沉积与油气成藏:以南大西洋周缘盆地为例

Tectonic-sedimentary features and petroleum accumulation in the passive continental margin basins of south Atlantic peripheries

被动陆缘原型盆地在各个地质历史时期广泛分布,是全球富油气盆地的主要盆地类型。现今被动陆缘盆地在全球主要分布在大西洋周缘、印度洋周缘、北冰洋周缘和地中海东南缘。通过对南大西洋周缘主要含油气盆地分析,将被动陆缘盆地分为伸展型和转换型两大类。根据沉积充填特征,伸展型被动陆缘盆地又可细分为含盐型、不含盐型和三角洲型。不同类型的盆地在区域上具有明显的分段特征,如可将南大西洋边缘分为南段、中段和北段。南段主要为伸展型不含盐被动陆缘盆地、中段为伸展型含盐被动陆缘盆地、北段主要为转换型被动陆缘盆地。中段尼日尔河流域还发育尼日尔三角洲高建设型被动陆缘盆地。基于已发现的被动陆缘盆地大油气田(>5亿桶油当量)分析,发现这几种类型的被动陆缘盆地均具有发现大油气藏的潜力,但油气成藏特征不同。

Passive margin basin is a main type of petroliferous basin, and the present-day passive margin basins are mainly distributed in the peripheries of Atlantic, India, Arctic Oceans and Southeast periphery of Mediterranean Sea. To focus on the south Atlantic type passive margin basins, the passive continental margin basins of south Atlantic peripheries can be divided into two categories of extensional basin and extensional basin with strong shear stress by using the technique of basin analysis. According to the characteristics of sedimentary filling, the former can be subdivided into salt basin, no salt basin and delta type basin, which divided South Atlantic margins into three segments of the southern, the middle and the northern sections from south to north. The south mainly consisted of extensional basins without salt, the middle section is salt basin, and the north is basins with little salts and strong shear stress. In the junction of the middle and north sections, a typical Niger delta passive margin basin is formed, which was controlled extremely by the Niger River. Based on the analysis of giant fields, these types of passive margin basins all present huge oil or gas potentials and different petroleum accumulation models.