The immiscibles: Capillarity effects in porous media - Pore-network modelling. Geologica Ultraiectina (318)

Abstract

Current theories of two-phase flow in porous media are based on the so-called extended Darcy’s law, and an algebraic relationship between capillary pressure and saturation. Both of these equations have been challenged in recent years, primarily based on theoretical works using a thermodynamic approach, which have led to new governing equations for two-phase flow in porous media. In this research, these equations and also other physical aspects of multiphase flow in porous media are studied. To gain detailed insights into the processes and for quantitative assessment pore-network modelling has been employed. In this work, we have developed robust quasi-static and dynamic pore-network models. Several quasi-static and dynamic pore-networks have been developed to study relationships between average phase pressures, average capillary pressure, and specific interfacial area during drainage and imbibition. Other aspects of flow in porous media such as rapping mechanisms, saturation profile, non-equilibrium effects in pressure and interfacial area are investigated. In addition to the investigation of physics of multiphase flow, we have developed new approaches for better presentation of porous media, which are employed in quasi-static models. Quasi-static simulations are done in three different media; a hypothetical porous medium, a two-dimensional micro-model, and a three-dimensional glass-bead column. Capabilities of the models in simulating experiments as well as providing more detailed information about the experiments are shown. This may be impossible and time-consuming in laboratory experiments. Furthermore, a dynamic pore-network model with improved numerical features is developed. New algorithms in dynamic pore-network modelling provide very flexible formulations to simulate the two-phase flow in different capillary numbers and different viscosity ratios for drainage and imbibition.