岩性圈闭盖层封闭动力学模型及其应用研究

Hydrocarbon sealing dynamic model research and application for shale cap rock of lithological reservoir

岩性圈闭的泥页岩盖层阻止油气突破的过程是一个阻力克服动力的过程,本文在此基础上建立了岩性圈闭盖层封闭动力学模型及相应的数学模型。该模型认为岩性油气藏中的油气突破泥岩盖层的过程也是一个力学平衡现象,动力包括储集层地层压力、浮力,阻力主要包括盖层地层压力、毛管压力。通过对单井古孔隙度及古埋深的恢复,可以对比成藏期目的层油气突破泥岩盖层的动力与阻力之间的大小关系,定量研究泥岩盖层封闭性演化过程。应用该模型发现,白家海凸起彩43井侏罗系三工河组及西山窑组在侏罗纪末期缺乏有效泥岩盖层,白垩纪末期三工河组中下部存在有效盖层,而西山窑组盖层的封闭能力一般。

The processing of shale cap rock preventing hydrocarbon breakthrough in lithological reservoir is a course of impetus subdue resistance. On the basis of theory,the article establish the hydrocarbon sealing dynamic model and mathematic model for shale cap rock of lithological reservoir. The models indicate that hydrocarbon breaking shale cap rock in lithological reservoir is a dynamics balance phenomenon. The impetuses include the formation pressure of reservoir and buoyant force. The resistances include the formation pressure of shale cap rock and capillary pressure. Following the restoration of the paleoporosity and paleoburial depth, the impetus and resistance of hydrocarbon breaking shale cap rock in oil pool forming period can be contrasted, and the cap formation sealing capability evolution can be quantitatively study. From the application of the models,we can found that the Sangonghe group and Xishanyao group of Jurassic System lack effective mudstone cap rock in the end of Jurassic. The effective mudstone cap rock is existing in lower-middle part of Sangonghe group and the sealing ability of Xishanyao group is very generalized in the end of Cretaceous.