Unsteady Filtration of the Oil-CO2 Flow in a Homogeneous Reservoir under Different Thermobaric Conditions

• Published in: Mathematical models and computer simulations 2021, Vol.13 (5), p.887-896
• Main Authors: Radaev, A. V., Plohotnikov, S. P., Tazyukov, F. Kh, Sabirzyanov, A. N., Salimyanov, I. T.
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Enhanced oil recovery; Filtration; Finite difference method; Fluid flow; Linear equations; Mathematical analysis; Mathematical Modeling and Industrial Mathematics; Mathematical models; Mathematics; Mathematics and Statistics; Permeability; Porous media; Reservoirs; Saturation; Simulation and Modeling; Solubility; Thermophysical models; Thermophysical properties; Viscosity
• ISSN: 2070-0482; 2070-0490
• DOI: 10.1134/S2070048221050185

An experimental stand is developed to study the hydrodynamics of the oil-supercritical CO 2 flow in a homogeneous porous terrigenous medium at pressures up to 25 MPa and temperatures up to 473K. The experimental stand allows measuring the solubility of carbon dioxide in oil and oil in carbon dioxide in the process of the unsteady filtration of the oil-supercritical CO 2 system in a low-permeability homogeneous porous medium in a dynamic mode. The solubility of the model low-viscosity oil when it is displaced from the model of a terrigenous homogeneous oil reservoir and the dynamic viscosity of the liquid oil-supercritical CO 2 substance are studied. Based on the obtained experimental data on the thermophysical properties of the oil-supercritical CO 2 system, a mathematical model is developed for the process of the unsteady filtration of the oil-supercritical CO 2 flow in a low-permeability homogeneous porous medium. The problem is solved numerically by the finite difference method. An implicit scheme in terms of pressure and an explicit scheme in terms of saturation, the so-called IMPES method, is used in the discretization process. At each moment of time, the pressure is calculated from a system of linear equations while the saturation is taken from the previous time layer. Then the saturation is recalculated explicitly using the found pressures. When discretizing the derivative for the adjacent nodes, the permeability is taken from the node in which the pressure is higher (that is, the upstream scheme is used). The convergence of the solution is controlled by performing numerical experiments on condensed grids. The developed mathematical model makes it possible to calculate the values of the displacement coefficient of the real oil. The mechanisms of enhanced oil recovery from permeable and low-permeability porous media are identified.