渤海湾盆地含油气层系区域分布规律与主控因素

REGIONAL DISTRIBUTION REGULARITY AND ITS CONTROLLING FACTORS OF OIL A ND GAS BEARING SERIES IN BOHAI BAY BASIN

渤海湾盆地含油气层系多、时代跨度大，各地区主力含油气层系明显不同，理清含油气层系分布规律，对油气勘探有重要意义。文中以构造演化历史和地层层序发育特点综合研究为基础，分析该盆地含油气层系的区域分布规律和主要控制因素。认为：（１）构造演化历史是多含油气层系形成的首要控制因素，决定了纵向油气分布的总体特点。构造演化历史相似的凹陷，一般具有相同的主要含油气组合，该组合探明油气储量占全凹陷的７０％￣８０％。（２）盆地外围隆起是主物源区，凹陷与盆外隆起的空间配置关系，对纵向层序组成和生储盖岩系发育特点有重要影响，进而控制含油气层系分布。（３）断裂带明显的走滑作用，可提高断层的封闭性，使较多油气聚集在下部层位中。（４）油气资源丰度高的凹陷，含油气层系时代跨度大，资源丰度较低的凹陷，主要油气藏分布在成熟生油岩体附近。

Multiple oil and gas bearing layer of a big time span occur in Bohai Bay Bas in, and the major assemblage is different from one part to another, so it is of great importance for exploration practice to acquire a deep understanding of the distribution of oil and gas series. On the basis of comprehensive study of tect onic evolution and sequence stratigraphy, this paper analyses the regional distr ibution regularity and controlling factors of oil and gas bearing series in the basin, and gets four conclusions. (a) The primary controlling factor accounting for the forming of multiple oil and gas series is the tectonic evolution which d etermines the overall vertical oil and gas distribution features. Sags with simi lar tectonic evolution history have the same major oil and gas bearing formation assemblage that generally contribute about 70%~80% of proven reserves of the wh ole sag. (b) The uplifts surrounding the basin are major sediment source areas . The spatial matching relations of a sag and the uplifts has significant influe nce on the composition of sequences and the development of source rockreservoi rcap rocks, thus controlling the vertical oil and gas distribution. (c) An evi dent strikeslip displacement may enhance the sealing ability of faults and ena ble oil and gas to accumulate in lower horizons. (d) For sags of high reserve ab undance, they have large time span of oil and gas series; for those of low reser ve abundance, the major reservoirs are near the mature source rock body.