苏北盆地油气田形成与分布——与渤海湾盆地比较研究

苏北-南黄海盆地与渤海湾盆地之间以鲁苏隆起相隔,对称分布于郯庐断裂两侧.由于两盆地所处的区域构造背景不同,致使其盆地演化、成烃演化、资源丰度、油气田规模差异很大.壳幔结构的同相性、晚始新世至渐新世18Ma的沉积间断、有机质演化程度低、断裂活动改造强烈等,是形成苏北盆地低丰度含油气特征的主因.苏北盆地与渤海湾盆地存在的成藏条件差异及其分布规律表明,苏北盆地缺乏形成巨型、大型油气田的条件,其勘探对象应该以中小型油气田为主,这已经被25年的勘探实践所证实,但深部烃源有形成较大规模气田的条件.

OIL AND GAS FIELDS FORMATION AND DISTRIBUTION OF SUBEI BASIN-RESEARCH COMPARED TO BOHAI BAY BASIN

Subei-south Huanghai Basin and Bohai Bay Basin are distributed symmetrically on the side of Tanlu fault,and are separated by Lusu uplift.The basin evolution,hydrocarbon generation,resource abundant,oil and gas field scale are different between two basins since they are located on different tectonic setting.The isopicphase of crust-mantle architecture,the hiatus of 18Ma from later Eocene to Oligocene,the lower evolution of organic matter,the strong reformation of fault activities etc resulted in the formation of the oil and gas-bearing characteristics of“small,fragmental,poor,scattered”in Subei Basin.The differences of reservoir formation conditions and distribution between Subei Basin and Bohai Bay Basin demonstrate that Subei Basin is lack of the conditions to form large oil and gas field,and the exploration objects should predominantly be medial-small scales.This has been verified by 25 years exploration, but the hydrocarbon from deep source rocks is of condition to form bigger gas fields.