CO2 foam flooding for improved oil recovery: Reservoir simulation models and influencing factors

• A mechanistic model of CO2 foam flooding was constructed.
• The model can describe generation, propagation, coalescence and collapse of foam.
• Primary parameters in the mechanistic model were determined.
• The mechanisms of CO2 foam flooding for improved oil recovery were investigated.
• Effects of various influencing factors on foam flooding performance were studied.

A mechanistic model of CO2 foam that allows for direct simulation of foam generation, propagation, coalescence and collapse was described in this study. The controlling parameters, such as reaction rate factors for foam generation, coalescence and collapse in presence of oil, the viscosity of foaming components and surfactant adsorption, were adjusted to match the experimental results of CO2 foam coreflooding. A three dimensional heterogeneous conceptual reservoir model was then built to study the mechanisms of CO2 foam flooding based the foam model. The simulation results show that CO2 foam flooding can improve oil recovery through a combination of various mechanisms, including selective blocking and conformance control, gas up-flow effect, reservoir energy support, and the improvement of displacement efficiency. The sensitivity and the effect of different influencing factors on the performance of CO2 foam flooding were investigated via the simulation models on various scenarios. CO2 foam flooding can achieve a better oil recovery in comparison with water flooding, CO2 flooding and WAG (water alternating gas) processes. Early CO2 foam injection is conducive to the improvement of oil recovery and the success of the project. CO2 foam flooding technique can be applied in a wide range of complex reservoirs, especially for highly heterogeneous reservoirs with high permeability channels, and reservoirs with different sedimentary sequences.