歧深地区双超压系统发育特征及油气成藏效应

Double Overpressure Systems and their Relationship with Hydrocarbon Accumulation in the Qikou Depression of the Bohai Bay Basin,China

在钻井实测储层压力(DST)、计算泥岩压力及地震资料解释的基础上,对歧深地区超压体系发育特征、分布规律和成藏效应进行了深入分析,认为歧深地区具有"三层压力结构,两个超压系统"特征。压力结构在纵向上可以划分为常压系统、上部弱超压系统和下部超压系统。超压从东营组开始出现,歧口凹陷中心超压最强,北大港东翼、歧口凹陷及板桥凹陷超压次之。双超压结构对歧深地区油气聚集有明显的控制作用,从而形成了"上油下气"分布格局,由此建立了"双压控藏"模式。

Over-pressured system is one of the controlling factors for hydrocarbon accumulation in sedimentary basins.In this study,the characteristics and spatial distribution of overpressured systems in the Qikou depression are analyzed based on the analysis of stratigraphic pressures from reservoir measurement as well as log and seismic data calculation.Our results show that the pressure systems in the Qishen area can be divided into 3 types：hydrostatic systems on the top,weak overpressured systems at the upper and overpressured systems at the lower parts.The overpressure phenomena initially occurred in the middle and bottom parts of the Dongying Formation,and the depths of their top interfaces of overpressure vary in different structural belts.Strong overpressures occur in the deeper areas of the Qikou depression and the overpressure is gradually weakened in the east margins of the Beidagang hill belt and the Banqiao sag.Overpressuring controls not only the physical compaction process of deeper sandstones,but also the migration and accumulation of hydrocarbon at deeper compartments.Hence,a model of ＂ double overpressure controlling hydrocarbon accumulation＂ is suggested.