Electric\nField Control of CO<sub>2</sub> Distribution\nin Kerogen Slit of Depleted Shale Gas Reservoirs: Implications for\nCO<sub>2</sub> Sequestration

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