Although there is a wealth of literature on experimental studies and theories of foam behavior, industry experience of foam enhanced oil recovery is still limited, and it remains a challenge to move from laboratory studies to field scale predictive simulations. This work describes a reservoir simulation study of foam enhanced oil recovery (EOR) processes, starting from a matched coreflood experiment, and extending the model to investigate foam behavior at a larger scale and over longer times.
A core-scale compositional simulation model is constructed, including chemical reactions to represent foam generation, adsorption and decay over time, with a functional representation of gas mobility reduction due to foam behavior. The simulation parameters are tuned to match production and pressure for a laboratory coreflood consisting of water, gas, surfactant and Surfactant-Alternating-Gas (SAG) injection phases. The core is modeled with 2D and 3D grids at coarse and fine scales and the results are extended to field scale sector models. Sensitivity runs are performed to determine the impact of key parameters on foam behavior for different model resolutions, sizes and timescales.
The impact of gravity override, heterogeneity, adsorption and decay can be observed even in core-sized models, and visualization of the simulated results over time shows the effect of grid design in capturing foam behavior in the core. At the field scale, simulations demonstrate qualitatively how foam improves oil recovery by reducing gas mobility and delaying breakthrough. However, upscaling and numerical dispersion effects can be significant when modeling chemical reactions and foam physics. The complexity and uncertainties of foam processes mean that additional measured data from experiments and pilot projects are needed, to develop confidence in predictions of field performance.
In this work, we aim to fill some of the knowledge gaps in simulation of foam EOR, by describing practical approaches for modeling and understanding foam processes at different scales. We focus on important parameters for upscaling from experimental results and make recommendations for further studies to assist with de-risking foam EOR projects.