南沙海域主要沉积盆地资源潜力分析

Analysis on the resource potential in the main depositional basins of Nansha area,South China Sea

南沙海域面积为82.6×104km2,含油气沉积盆地发育,石油地质条件优越,其中大型盆地有曾母、北康、南薇西、中建南等。该区研究程度很低,据现有资料,通过对区域构造、地层、沉积储层、烃源岩特征等石油地质条件的综合研究,认为曾母、北康、南薇西、中建南等盆地经历了断陷期和坳陷期沉积演化后,沉积了巨厚的新生代地层,自下而上发育了冲积扇相、河湖相→滨岸沼泽相→滨海相→浅海相→半深海相沉积体系,区域上存在始新统、渐新统、中新统三套烃源岩,以及渐新统砂岩、中新统生物礁两套主要储层,区域盖层为上新统和更新统浅海—半深海相泥岩。

The acreage of Nansha area of South China Sea is 82.6×10^4km^2, where hydrocarbon basins had developed with good petroleum geology conditions, the main depositional basins include Zhengmu, Beikang, Nanweixi and Zhongjiangnan. Based on the comprehensive research on the geological conditions such as regional structure, formation, depositional reservoirs, features of hydrocarbon source rocks, it is found that the basins in the study area deposits massively thick Cenozoic formation after experiencing rifting period and depression period. The developed sedimentary facies are alluvial fan facies, river-lake facies, shore marsh facies, littoral facies, shallow sea facies, and bathyal facies. There exist three sets of hydrocarbon source rocks including Eocene, Oligocen and Miocene, and two sets of main oil formations, ie： Oligocene sandstone reservoir and Miocene bioherm reservoirs. The regional cap rocks is Pliocene and Oligocene shallow water-bathyal facies mud.