A novel approach to handle continuous wettability alteration during immiscible CO₂ flooding process

Wettability has been recognized as one of the main parameters that control the remaining oil-in-place. Knowledge of wettability alteration during displacement is essential to understand the displacement mechanisms and to recover oil efficiently. Continuous alteration of wettability and other related properties need to be addressed properly for an effective approach to enhanced oil recovery (EOR). Review of the literature reveals that much laboratory work, including core and micro-model flooding, was conducted to investigate wettability alteration during CO₂ flooding process. However, limited research on numerical and/or analytical modeling of such wettability alteration has been reported. Moreover, to the best of our knowledge, published numerical and/or analytical models are time-independent solutions. Ignoring this time dimension creates a significant knowledge gap between such solutions and reality. To mitigate this shortcoming, a novel approach was developed to handle wettability alteration on continuous basis during immiscible CO₂ flooding process. A mathematical model was developed to incorporate continuous time function for immiscible CO₂ flooding process. During the development of the model equation, Cory relative permeability model was utilized. In this model, a new, modified Corey relative permeability model was incorporated to calculate the phase relative permeability as a function of wettability. A numerical, 1-dimensional, two-phase immiscible simulation scheme was built utilizing MATLAB program to solve the model equations. The results showed that inclusion of continuous wettability alteration model is believed to predict oil displacement and sweep efficiency more realistically.