莱州湾凹陷中央构造带断层活动性及其控藏作用

摘要

莱州湾凹陷中央构造带油气藏分布具有“纵向上分层,平面上分带”的特征.为研究同一构造带上油气藏分布差异性,利用前人对断层封闭性评价的方法对莱州湾凹陷中央构造带上控藏断层的封闭性进行了系统评价,并采用了地球化学手段和盆地模拟手段将构造演化史与其油气成藏史相结合,厘清了莱州湾凹陷中央构造带的油气成藏规律.研究结果表明:断层活动史与油气充注过程相匹配是莱州湾凹陷中央构造带油气成藏的关键因素,早期活跃的断层活动有利于油气的向上运移聚集成藏,晚期活动较弱的断层相对利于油气的保存;不同断层封闭性的差异导致了油气藏平面上分布的差异性,同一断层垂向封闭性的不同控制了油气纵向的分层性.在勘探过程中应结合断层的封堵性来确定勘探目的层位,降低勘探风险.%The hydrocarbon reservoir distribution in the central structure belt of Laizhou Bay Sag is characterized by " layering in longitude and zoning in latitude",in order to figure out the distribution differences in the same tectonic belt,with the help of the previous evaluating method of the fault sealing,the systematical evaluation was conducted for the sealing of the reservoir-controlling fault in the belt,and moreover by means of the geochemical and basin simulation methods,the tectonic evolution and the hydrocarbon accumulation histories were combined,the accumulating laws of the belt were made clear.The study achievements show that the history of the fault activi ties and the petroleum enriched process are the key factors of the accumulation in the belt,the activities in the early period is favorable to the upward migration and accumulation of the oil and gas,while in the late stage the fault with rather weaker activities is prone to the preservation of the hydrocarbon;different fault sealing results in the differential of the petroleum reservoir distribution in horizon,for the same fault with different sealings,the vertical layering property is dominated for the oil and gas.The process of the exploration,the explored target layer should be determined with the combination of the fault sealing so as to reduce the exploration risk.