南海北部陆坡深水盆地特征及其油气勘探潜力

Abstract

深水油气勘探是当今油气勘探的主要方向，南海北部深水区具有世界重要深水含油气盆地类似的特征。南海北部陆坡发育一系列深水被动陆缘盆地，这些盆地发育有较厚的中、新生代沉积地层。勘探表明盆地油气地质条件好，发育有中、新生界的多套烃源岩，包括湖相泥岩、海陆过渡相泥岩和海相泥岩。圈闭类型以大型构造和岩性圈闭为主，储层以第三系深水扇体类型的高孔高渗储层为主，油气类型以油为主。深水区发育有大量油源断层、多个不整合面和大面积连通砂体，从而构成了良好的油气输导体系。中新世晚期的构造运动，使得构造形成期、断裂活动期与排烃高峰期匹配良好，据盆地模拟结果，深水区有两个排烃高峰期与构造形成期相匹配，而晚期断裂活动晚于构造形成期,因此有利于油气沿断层垂向运移至较浅部位的圈闭聚集成藏。南海北部陆坡深水区具有良好的油气勘探潜力。The deep-water oil and gas exploration is the main direction of today’s oil and gas exploration. Deep-water basins in northern South China Sea have the similar characteristics area of the world’s major deep-water petroleum-basin. Northern South China Seadeveloped a series of deep-water passive margin basins, these basins developed thick sedimentary strata of Mesozoic and Cenozoic. Exploration conformed that these basins had good petroleum conditions of many sets of Cenozoic source rocks, including lacustrine mudstone, paralic mudstone and marine mudstone. The types of trap are mainly the large structural and lithologic traps. Reservoirs are Tertiary deep-water-fan sands with high porosity and permeability. The main Petroleum type is oil. There are many faults, unconformities and large good connectivity sands developed in deep-water basins, thus a good oil and gas transporting system is constituted. According to the results of basin modeling, deep-water basins have two peaks of hydrocarbon generation. The period of fold and fault activity during late Miocene matched well with the peak of hydrocarbon generation and expulsion. Deep-water basins ofNorthern South China Seahave good potential for oil and gas exploration.