Analysis of Phase Displacement Paths in Gas Injection and Three-Phase Flow in Water-Alternating-Gas (WAG) Processes

Abstract

TX 75083-3836 U.S.A., fax 01-972-952-9435. AbstractGas injection and water-alternating-gas (WAG) displacements are becoming increasingly important as EOR processes in a wide range of reservoirs. Although the conservation equations can be written down, the resulting multiphase macroscopic flow equations contain quantities which are not well understood, viz. the three-phase relative permeabilities and capillary pressures (denoted 3PRPs and 3PCPs in this paper). There are a number of published empirical correlations for three-phase relative permeability (3PRP) based on the corresponding two-phase relative permeability functions e.g. Stone Models I and II 1,2 , the Baker saturation-weighting model 3 , etc. These models are purely empirical and have only been partially validated for data in strongly water wet rocks and most reservoirs are not strongly water wet. In addition, these models embody very little understanding of the pore scale physics of three-phase flow. Recently, a number of advances have been made on the understanding of the pore scale physics of three-phase flow in water wet porous media 4 and also in systems of non-uniform wettability 5-8 , where the water-wet case is a particular limiting case. How this pore scale physics works through to the effective macroscopic flow parameters is still a matter of active research.