大庆长垣砂岩储层构造油藏油水界面控制因素研究

Research on Controlling Factors of Oil-Water Interface of Structural Oil Reservoirs in Sandstone Reservoirs of Daqing Placanticline Structure

大庆长垣构造上的喇嘛甸、萨尔图、杏树岗油藏是砂岩储层背斜构造油藏,油藏东、西两翼的油水界面深度不一致,过去有水动力及地应力等许多种地质成因解释。利用构造油气成藏重力分异的物理学原理,根据毛管力与浮力平衡理论推导出能够刻画油水界面分布规律的毛—浮方程,指出油藏内任意位置的油水界面深度是由该处储层的孔隙结构,即由排替压力所对应的孔隙半径(rd)大小决定的。rd与储层物性呈正相关,由于储层非均质(岩性因素)存在,一般背斜构造油藏的油水过渡带(段)表面(油水界面)是波状起伏、厚度有变化的锥柱形。

Lamadian, Saertu, and Xingshugang oil reservoirs located in placanticline structure of Daqing Oilfiledare sandstone reservoirs with anticlinal structure. The depths of oil-water interface are different in the eastern and western limbs, which have been interpreted by many geological origins, such as hydrodynamic force and terrestrial stress. Based on the physical principle of gravity differentiation of structural oil and gas reservoirs, as well as the theory of equilibrium between capillary force and buoyant force, the equation of capillary force and buoyant force is deduced, which can be used to describe the distribution law of oil-water interface. A conclusion is drawn that the depth of the oil-water interface in any position of the reservoir is determined by its pore configuration, that is, the size of the pore radius (rd) corresponding with the displacement pressure. Rd has positive correlation with reservoir properties. Due to the existence of reservoir heterogeneity (lithologic factors), the oil/water transitional zone and oil-water interface of general anticlinal structural oil and gas reservoirs are undulating, as well as the thickness tends to be conico-cylindrical.