The paper presents an adjusted mathematical model of two-phase filtration processes in fractured porous media. Traditionally, the equations of two-phase filtration in a medium of dual porosity are based on the laws of conservation of oil and water phases in fractured and matrix (block) rock spaces. These equations are interconnected by some functions that describe phases flow between fractures and blocks, and these functions are taken proportional to the pressure difference between the phases in the rocks matrix and fractures. With the exception of transient processes, characterized by a sharp change in reservoir pressure, as occurs, for example, during hydrodynamic studies in wells, the indicated difference in hydrodynamic pressures in long-term waterflooding of productive formations is due only to capillary forces. For this reason, it is traditionally assumed that the displacement of oil from hydrophilic rocks matrix is due precisely to the processes of capillary impregnation of these blocks. At the same time, as shown in the article, mass transfer between rock matrix and fractures is also determined by the processes of mixing of two-phase fluid flows in the fractured space of the rock, and comparable in intensity to capillary impregnation, which also leads to a decrease in oil saturation of matrix and, accordingly, an increase in oil saturation of the fractured space. The proposed mathematical model, which takes into account both the processes of capillary impregnation of matrix and the mass transfer due to mixing of fluid flows in fractures, will allow a more adequate description of the processes of two-phase filtration in fractured-porous reservoirs.
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