南沙海区沉积盆地油气资源评价及重点勘探地区

EVALUATION OF HYDROCARBON RESOURCES AND KEY EXPLORATION AREAS IN NANSHA BLOCK, SOUTHERN SOUTH CHINA SEA

我国南沙海域分布有曾母、万安、南沙海槽、礼乐等众多盆地。这些新生代沉积盆地构造类型多、面积大,新生界巨厚,邻近陆坡的大陆架十分宽广,塑造了多个三角洲,是重要的含油气资源区。盆地的主要烃源岩为渐新世—中中新世湖相泥岩以及下海岸平原沉积。储层发育有砂岩、灰岩(礁灰岩)、基岩等。区域性盖层为上新统—第四系广海相泥质岩。南沙海域含油气构造,具有规模大,隆起幅度高,类型多,成群成带分布等特点。应用波阻抗、烃类检测或模式识别等处理技术,通过盆地模拟技术和沉积岩体积法对南沙海域进行了油气资源评价,其总资源量为581.0047×108t,属于我传统海疆线内达372.0704×108t。文中最后指出曾母盆地的西、北部,万安盆地的南部和南沙海槽盆地的北部是近期重点勘探地区。

Several Cenozoic sedimentary basins, as characterized by multi - tectonic types and thick Cenozoic sediments, are distributed in the Nansha area. The main hydrocarbon source rocks for the basins consist of lacustrine mud and lower coastal plain sediments from Oligocene to Middle Miocene. The reservoir is composed of sandstones,limestones （reefs） and basement rocks. The cover rocks are marine mudstone from Pliocene to Quaternary. The structure traps occur on a large scale and normally extend along a zone. Based on basin modeling and sediment volume calculation results and by using a combination of techniques including wave impedance, petroleum detection and pattern recognition, etc. , the authors calculated that the total hydrocarbon resource is 581. 0047×10^8 t in the entire South China Sea, and is 372. 0704 x l0s t in sea areas falling under the traditional boundary of China. Finally, the authors pointed out that the North and west parts of Zengmu Basin, the South part of Wanan basin and the north part of Nansha basin are the key exploration areas for present hydrocarbon prospecting.