Electric Field Control of CO₂ Distribution in Kerogen Slit of Depleted Shale Gas Reservoirs: Implications for CO₂ Sequestration

Abstract

Finding effective methods to enhance the sequestration of CO 2 in depleted shale is always a concern for carbon neutrality. It is found that an electric field can strengthen CO 2 adsorption in the electrochemistry field. Considering the oilfield site has plenty of green electricity induced by solar, wind, and photovoltaic power generation, applying an electric field to improve CO 2 sequestration appears to be a viable idea. However, the performance of the electric field on the CO 2 distribution in the kerogen slit of shale remains unclear. This paper employs molecular dynamics (MD) simulation to address this issue. Moreover, the factors of electric field strengths, electric field directions, and sizes of the kerogen slit on the distribution of CO 2 near the kerogen wall are also explored. The results show that a Z-direction electric field aligns CO 2 molecules in a style where the oxygen (O) from the CO 2 molecule faces the carbon (C) from the kerogen wall, enhancing the accumulation of CO 2 molecules near the wall of the kerogen slit in depleted shale. Notably, there exists an optimal electric field strength. Specifically, a 0.5 V/Å electric field can enhance the accumulation of CO 2 molecules near the kerogen wall by 9.45%. The Z-direction electric field has a more significant effect compared to the X and Y directions. Moreover, the increased size of the kerogen slits can cause more CO 2 molecules to accumulate near the kerogen wall. The obtained results indicate that the electric field can be a promising technology for strengthening CO 2 sequestration in depleted shale. This insight can guide the application of electric field technology for enhancing the sequestration of CO 2 in depleted reservoirs.