Abstract
Foam, a dispersion of gas in liquid, has been investigated as a tool for gas mobility and conformance control in porous media for a variety of applications since late 1950s. These applications include enhanced oil recovery, matrix acidization treatments, gas leakage prevention, as well as contaminated aquifer remediation. In order to understand the complex physics of foam in porous media and to implement foam processes in a more controllable way, various foam modeling techniques have been developed in the past three decades.
This paper reviews modeling approaches obtained from different publications for describing foam flow through porous media. Specifically, we tabulate models based on their respective characteristics, including empirical and semi-empirical as well as mechanistic population-balance foam models. In various population-balance models, how foam texture is obtained and how gas mobility is altered as a function of foam texture, among other variables, are presented and compared. It is generally understood that both the gas relative permeability and viscosity vary in the reduction of gas mobility through foam generation in porous media. However, as the two parameters appear together in the Darcy's equation, different approaches have been taken to alter the mobility in the various models: only reduction of gas relative permeability, increasing of effective gas viscosity, or a combination of both. The applicability and limitations of each approach are discussed. How various foam generation mechanisms play a role in the foam generation function in mechanistic models is also discussed in this review, which is indispensable to reconcile the findings from different publications. Additionally, other foam modeling methods, such as the approaches using the fractional flow theory and those using the percolation theory, are also reviewed in this work. Several challenges for foam modeling, including model selection and enhancement, fitting parameters to data, modeling oil effect on foam behavior, and upscaling of foam models are also discussed at the end of this paper.
