Mechanistic simulation of continuous gas injection period during surfactant-alternating-gas (SAG) processes using foam catastrophe theory

The use of foam for mobility control is a promising means to improve sweep efficiency in subsurface applications such as improved/enhacned oil recovery and aquifer remediation. Foam can be introduced into geological formations by injection gas and surfacnt solutions simultaneouly or alternatively. Alternating gas and surfactant solutions, which is often referred to as surfacnt-alternating-gas (SAG) processes, is known to effectively create fine-textured strong foams in situ by repeating draining age foam catastrophe theory which exhibits three foam states (weak-foam, strong-foam, and intermediate states) and two strong-foam regimes (high-quality and low-quality regimes). Using both mechanistic foam simulation technique and fractional flow analysis which are consistent with foam catastrophe theory, this study aims to understand the fundamentals of dynamic foam displacement during gas injectionin SAG process. The results revelaed some important findings; (1) the complicated mechanistic foam fractional flow curves (f(w) vs. S-w) with both positive and negative constructing a tangent line from the initial condition: (2) none of the conventinal mechanisitc foam simulation and fractional flow anlaysis can fully capture sharply changing dynamic foam behvariour at in this study; (3) four foam model parametsr (del p(0), n, C-g/C-c, and C-f) can be determined systematically by using an S-shaped foam catastrophe curve, a two flow-regime map, and a coreflood experiment the inlet effect which explains a delay in strong-foam propogation near the core face is scaled by the system length, and therefore the change in system length requires a new set of individual lamella creation and coalescence parameters (C-g and C-c). (C) 2010 Elsevier Ltd. All rights reserved.