Asphaltene deposition simulation in porous media during CO₂ injection using Lattice Boltzmann Method

Abstract

Carbon dioxide (CO₂) injection in oil reservoirs is a potential means of Enhanced Oil Recovery (EOR) and reducing greenhouse gas. Change in the thermodynamic condition and composition due to the CO₂ injection process may trigger the asphaltene precipitation and deposition which directly affects the efficiency of the EOR process. Predicting the possibility of the asphaltene issue under different operating conditions can help the oil industry for better process design, handle the potential operational problems and estimate the production cost. In spite of, the existence of different modeling approaches based on conventional numerical methods, the lack of a flexible and more comprehensive modeling approach is inevitable. The new and advanced numerical method, called the Lattice Boltzmann Method (LBM) covers the limitations of the conventional numerical methods in dealing with complex boundary conditions and incorporating the microscopic interactions. This study is aiming at the modeling of the Asphaltene deposition, and it’s effect on the fluid flow in porous media during an immiscible injection of CO₂ with applying the LBM as the main simulator engine that gets fed by the given phase behavior to take the asphaltene deposition into account as well. Porosity and CO₂ injection velocity are the changing factors in this study. Applying the same condition on two mediums, it has been seen that the recovery factor is 22.5% higher and deposited asphaltene is 2.56% lower in a more porous medium that is attributed to uniform pore size distribution and higher absolute permeability of the more porous case. Furthermore, the fingering phenomena seem to be high in a less porous medium which causes an early breakthrough. Studies on the CO₂ injection velocity effect showed that by increasing CO₂ injection velocity by 2 times and 3 times, the recovery factor increases 4% and decreases 6%, respectively. A decrease in recovery factor is attributed to the asphaltene deposition at which the deposited asphaltene is two times higher at injection velocity of 3