Lattice gas automata simulations of a single-phase and two-phase flow in heterogeneous porous media

Abstract

Modeling of fluid flow in porous media and predicting its performance is one of the important subjects in petroleum engineering. This research reports the development of a lattice gas automata method to study and simulate a single-phase and two-phase flow in heterogeneous porous media as an alternative to conventional methods (finite difference and finite element). In this work, the FHP-II (Frisch, Hasslacher and Pomeau, FHP) model of lattice gas automata was developed to simulate microscopic fluid flow and estimate the macroscopic properties of heterogeneous porous media. Heterogeneity of the porous media was constructed by placing solid obstacles randomly in a two-dimensional test volume. Effects of grain shape and size geometry, and their distribution in the porous media were taken into account. In addition, macroscopic properties of the heterogeneous porous media were estimated in terms of the shape, size, number of the solid obstacles and by the distribution of the solid obstacles within the volume. In the single-phase flow simulation part, a heterogeneous porous media was constructed, and correlations between various macroscopic properties, i.e., tortuosity, specific surface area, effective porosity and permeability were obtained. In the two-phase flow simulation part, the phase separation of the two immiscible fluids was described. Furthermore, the surface tension and capillary pressure were also estimated. The displacement mechanisms of carbon dioxide to displace oil and displacement efficiency of the process in the heterogeneous porous media were also predicted. Generally, the lattice gas automata simulation produced similar results with previous researchers and experiments. Errors of between 10% and 25% were associated with the computed results from the single-phase flow simulation part for the permeability prediction, compared with the laboratory experiments, while for the immiscible fluids displacement process it was less than 5%. Based on the results, it is obvious that the lattice gas automata method was indeed capable of being applied in petroleum engineering for simulation of a single-phase and two-phase flow in heterogeneous porous media.