Combination of double and single cyclic pressure alternation technique to increase CO sub 2/sub2 sequestration with heat mining in enhanced geothermal reservoirs by thermo‐hydro‐mechanical coupling method

摘要

Summary The rise in global temperature due to an unceasingly increase in non‐condensable gases (NCG) prompts more development of safe and economical CCUS (Carbon Capture Utilization and Storage) technologies. Carbon dioxide (CO 2 ) sequestration with heat mining in deep enhanced geothermal systems (EGSs) is one of the promising methods to reduce CO 2 emitted to the atmosphere. In this study, a cyclic alternation of pressures at the injection and production wells is applied in an EGS for heat mining together with CO 2 deposit. Simultaneous alternation of the injection and production pressures can significantly increase the amount of CO 2 sequestrated compared to applying a fixed pumping or withdrawing pressures at the injector and producer respectively. At the injection well, alternation in pumping pressures at high frequency (small interval of days) increased CO 2 sequestration rate. Reducing the pumping frequency resulted in the lowering of the total amount of CO 2 sequestrated, lesser than using a fixed pumping pressure. The alternation in pumping frequency has a direct relationship to the CO 2 sequestration rate. The frequency of the injection and production pressures refers to the interval in days of the interchange in pressure between high to a low value and vice‐versa. Furthermore, simultaneous alternation of pressures at the injection and production wells respectively (double cyclic method) improved geothermal heat extraction efficiency, thus higher performance for both geothermal and CO 2 sequestration projects.