珠—坳陷半地堑成藏系统成藏模式与油气分布格局

Accumulation Pattern and Hydrocarbon Distribution of Half-graben Accumulation System in Zhuyi Depression

为了更好地分析珠江口盆地珠一油气区油气成藏规律和指导勘探实践,以珠一坳陷半地堑为成藏系统,以构造演化为主线,着眼于成藏要素组合,建立半地堑级的油气成藏模式。通过半地堑不同构造带烃源岩条件、油气输导条件、储盖组合条件等成藏要素的综合分析,认为研究区半地堑成藏系统油气成藏模式可分为缓坡带油气成藏组合模式、陡坡带油气成藏组合模式、洼陷带油气成藏组合模式和凸起带油气成藏组合模式共4大类型。断陷湖盆地质结构、地层产状和流体势确立了油气运移主方向及油气分布格局。从油气资源分配角度考虑,研究区半地堑可分为缓坡优势型半地堑、陡坡优势型半地堑和近平衡型半地堑共3种结构类型,不同类型半地堑成藏系统油气分布格局明显不同。

To analyze the hydrocarbon accumulation law of Zhuyi oil and gas zone in Pearl River Mouth Basin, this paper establishes a halfgraben hydrocarbon accumulation model on the basis of the halfgraben accumulation system in Zhuyi depression, focusing on structural evolution and accumulation element combination. Based on analysis of the accumulation elements, such as source rock, hydrocarbon migration conditions and reservoir-cap assemblages in the different structural zones of half grabens, it is assumed that the hydrocarbon accumulation pattern of the half-graben ambulation system in the research area can be divided into four types – hydrocarbon accumulation assemblage in gentle slope zone, steep slope zone, sag zone and uplift zone. The main direction of hydrocarbon migration and hydrocarbon distribution patterns are determined by geological structure of rift lake basin, formation occurrence and fluid potential. From the angle of hydrocarbon resources distribution, the half grabens in the research area can be divided into three types of structure, such as gentle slope predominant half graben, steep slope predominant half graben and nearly balanced half graben. These three half grabens have apparently different distribution patterns of hydrocarbon accumulations.