高邮凹陷古近系水动力作用与油气运聚机理

在分析高邮凹陷古近系现今地层水化学、水动力场分布特征的基础上,结合高邮凹陷构造演化特征,对高邮凹陷古近系地下水动力的成因和演化及其与油气运聚的关系进行了深入研究,预测了下一步有利勘探区.结果表明：高邮凹陷上含油系统南断阶和北部柘垛低凸起为大气水下渗向心流区,深凹带发育泥岩压实水离心流;中含油系统大气水下渗影响范围变小,泥岩压实水离心流区向北偏移,影响范围进一步减小,越流泄水区范围扩大.油气的运移、聚集、成藏与地下水动力密切相关.南断阶、北部柘垛低凸起及局部隆起区在构造抬升剥蚀期,断裂活动、开启,大气水沿断裂带下渗,同时油气通过浮力沿断层再分配或者散失,油气不断运移调整、油气藏遭受破坏;而高邮凹陷内斜坡、永安-富民西部地区、南部断阶带真②断裂下盘及周庄-陈堡地区水动力条件优越,为较有利勘探区.

The hydrodynamics of Paleogene Formation and mechanisms of hydrocarbon migration and accumulation in Gaoyou sag

Based on the distribution characteristics of Paleogene Formation′s present hydrochemistry and hydrodynamic field and combined with the structural evolution of Gaoyou sag,the hydrodynamic origin and evolution of Paleogene Formation and its relationship with hydrocarbon migration and accumulation were deeply studied.And then certain areas with favorable exploration potential were proposed.The results show that in upper oil-bearing system of Gaoyou sag,centripetal flow of meteoric water infiltration was developed at the southern step-fault area and the northern Zheduo low uplift,whereas the centrifugal flow of mudstone compaction-releasing water was developed in the deep zone of sag.In middle oil-bearing system of Gaoyou sag,the area affected by meteoric water infiltration became smaller,and the centrifugal flow migrated towards the north.So the influence region was further reduced,leading to more expansion of the cross-formational area.The migration and accumulation of oil and gas has the close relationship with the dynamics of groundwater.In the southern of step-fault zone,northern of Zheduo low uplift and some local upwelling areas,faults developed and opened,and the meteoric water infiltrated during the tectonic uplift and erosion stage.Oil and gas,driven by floatation,was redistributed upward along the faults or even lost,causing serious destruction of the paleo-pools.Therefore,the inner slope of Gaoyou sag,the western region of Yong′an-Fumin oilfields,the lower wall of Zhen② fault in southern step-fault zone and the Zhouzhuang-Chenbao are the areas with favorable exploration potential due to advantages of their hydrodynamic conditions.