This article presents a comprehensive reservoir mathematical model designed to analyze and predict oil fields development in the depletion mode. A special feature of the model is that it takes into account the dependence of permeability and nonlinear dependence of reservoir porosity on reservoir pressure. This is important in cases when, during depletion, reservoir pressure decreases below the level of oil gas saturation and a significant change in the physical properties of the reservoir and fluids is observed. The model includes two main modes of oil reservoir operation during depletion: elastic and dissolved gas. In the elastic mode, a decrease in reservoir pressure causes rock compaction, which maintains well productivity due to elastic deformations. In the dissolved gas mode, with a drop in pressure, gas begins to release from the oil, passing into a free phase. This leads to significant changes in phase permeabilities and complicates the filtration process, requiring a special approach to modeling. For verification a numerical simulation was performed based on data obtained from one of the fields of the North Caucasus oil and gas province. The calculation results confirmed the need of taking into account the dependence of permeability and the nonlinear dependence of porosity on pressure when modeling and predicting the development of oil fields for depletion. The model allows increasing the accuracy of calculations, which can contribute to the optimization of oil production processes and an increase in the hydrocarbon recovery factor. This approach can be used in fields characterized by a complex nature of changes in filtration and capacity properties with a drop in reservoir pressure.
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