北黄海盆地地质构造特征及其在油气勘探中的意义
CHARACTERISTICS OF GEOLOGIC STRUCTURES OF THE NORTH YELLOW SEA BASIN: IMPLICATIONS FOR PETROLEUM EXPLORATIONS
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摘要: 通过对近年来在北黄海盆地的油气勘探认识的总结,结合区域地质研究成果,从盆地的基底结构、地质结构和主要构造类型等方面对北黄海盆地的地质构造特征进行了分析。提出北黄海盆地是在前中生代结晶基底之上发展起来的,盆地经历了走滑拉分(J3-K1)、断陷(E2-E3)、拗陷(N-Q)3次主要的沉降作用过程,形成了下、中、上3个构造层,在盆地内发育了断裂、褶皱和潜山3种基本构造类型。盆地的这种构造特征为盆地内油气的生成运聚提供了物质基础和边界条件,特别是晚侏罗世-早白垩世由于走滑拉分形成的下构造层具有较好的生烃物质基础,同时还有良好的圈闭发育条件,后期的构造改造也有利于油气的生成聚集,应是北黄海盆地的主要勘探对象。Abstract: On the basis of latest oil exploration data from the North Yellow Sea basin and together with regional geologic research results,the authors have analyzed geologic structures of the basin at the angles of basement structures,geologic structures and main tectonic types.It is suggested that the basin has its development based upon Pre-Mesozoic crystalline basement and undergoes three large subsidence processes represented by three structural layers,and as a result of that,three basic tectonic types(fault,fold and buried hill)are formed in the basin.These structural characteristics provide good conditions for generation,migration and accumulation of oil in the basin.Especially the lower structural layer of late Jurassic-early Cretaceous is the best hydrocarbon-producing layer that has good trap development conditions and whose reworking afterwards favors the generation and accumulation of oil and thus should be the major exploration target layer in the North Yellow Sea basin.