Numerical Simulation of Hydrocarbon Mixtures Mass Transfer Processes and Flow in a Reservoir Rock

Abstract

Currently, a number of software products (PVTSim, WinProp CMG, Aspen HYSYS, etc.) are used in the oil and gas industry, simulating the interfacial mass exchange in natural oils, gas condensate mixtures, etc. Existing software products use the vapor-liquid equilibrium calculation methods (flash-calculations) based on various cubic equations of state for the hydrocarbon mixtures. Peng–Robinson and Soave–Redlich–Kwong equations of state are primarily used in these products. Within work (1), the author of current work created a software package in the Python language that can carry out vapor-liquid equilibrium numerical simulations for hydrocarbon mixtures (the paraffin series was considered) using three different cubic equations of state: Peng–Robinson, Soave–Redlich–Kwong and Brusilovskiy. The development of this software package allowed comparison the vapor-liquid equilibrium parameters for hydrocarbon mixtures calculated using these three equations of state. The vapor-liquid equilibrium calculation for multicomponent hydrocarbon systems is also carried out in the numerical simulation of physicochemical processes in hydrocarbon deposits (simulators Eclipse 300, CMG GEM, etc.). Such calculations are important when the project to develop hydrocarbon deposits involves the injection of multicomponent gas mixtures ("fat" gas, air, etc.) in order to increase oil recovery. Here, using the created software package, we discuss how each of the three equations of state impact numerical simulation results of mass transfer processes between liquid and gas phases under fixed thermobaric conditions. The calculations help analyze how the choice of equation impacts simulation's results when extracting hydrocarbons. The result of this work was the development of a software package for calculating the PVT parameters for multicomponent hydrocarbon systems in a compositional model based on the cubic equation of state (Peng–Robinson and Soave–Redlich–Kwong). The thermodynamic characteristics, such as density, viscosity and phase component composition, were calculated based on setting the total component composition, equation of state, pressure and temperature. After that, the results of the developed software package were compared with the results obtained using the popular software products for calculating the PVT properties for multicomponent hydrocarbon systems.