金湖凹陷隐性断裂带形成机制及分布

Formation Mechanism and Distribution of Buried Fault Zones in the Jinhu Sag

金湖凹陷基底存在北东、北西向两组断裂。北西向基底断裂活动较弱,对盖层变形影响较小,在盖层中多以隐性断裂带显现;北东向基底断裂活动强烈,对凹陷盖层变形影响较大,不仅形成了凹陷东部边界杨村断裂在内的多条显性断裂,而且形成了多条隐性断裂带。凹陷中部的北东向石港显性断裂带将凹陷分割成西部斜坡带和东部凹陷带。东部凹陷带受基底北西向断裂隐性活动的影响呈现南北分段特征。凹陷盖层中还发育了大量近东西走向的三、四级正断层,它们大致平行成带分布,形成了宝应平行雁列式断裂构造带、唐港雁列式断裂构造带、卞闵杨平行雁列式断裂构造带、西斜坡平行入字型断裂构造带、汊涧泥沛平行雁列式断裂构造带等一系列油气富集区带。上述构造带中的油气藏分布明显受到北东和北西向基底断裂活动影响,呈现北东、北西或近南北向成带、成串分布特征。应用区域地质、重磁等资料开展隐性断裂带预测,识别出10条北东向、5条北西向、6条南北向隐性断裂带。沉积盖层中形成的这些隐性断裂带控制了储集砂体分布、改善了储层物性、使隐性圈闭成带成串分布,是油气聚集成藏的有利区带。

There are many NE-trending faults and NW-trending faults in the Jinhu sag.NW-trending basement faults are weak with a little influence on the sedimentary cover,while there are NW-trending buried fault zones in the cover.NE-trending basement faults are strong with important influence on the sedimentary cover.The Yangcun fault zone and a lot of NE-trending buried fault zones formed in the sedimentary cover.The Shigang major fault zone divids the Jinhu sag into the western slope belt and the eastern sag belt.The eastern sag belt was influenced by＂buried＂activity of the NW-trending basementfaults presenting as segments from tht north to the south.There are a great quantity of nearly parallel third or fourth-order normal faults in the cover in the Jinhu sag.This fault belts include Bao-Ying parallel-echelon fault belt,Tang-Gang echelon fault belt,Bian-Min-Yang parallel-echelon fault belt,western slope parallel fault belt,Chajian-Nipei parallel-echelon fault belt,contributing to several enriched zone of oil and gas,and this hydrocarbon reservoirs are influenced by NE-trending basement faults and NW-trending basement faults,presenting as NE-,NW-,NS-trending stripe or string.On the basis of regional geological data,gravity and magnetic data,10NE-trending buried fault zones,5NWtrending buried fault zones,6 NS-trending buried fault zones are identified.The buried fault zones control the distribution of the sandbody,and improve the reservoir physical property.They make the buried reservoir as zonal distribution,which are favorable zones for hydrocarbon accumulation.