地质科技通报 (May 2024)
Performance analysis of thermal energy storage for space heating and CO2 sequestration in depleted oil and gas reservoirs
Abstract
Objective Thermal energy storage and CO2 sequestration in depleted oil and gas reservoirs can not only solve the problem of seasonal solar thermal energy storage but also increase the share of renewable energy space heating and enhance the economy of CO2 geological sequestration. Methods A novel scheme of thermal energy storage for space heating and CO2 sequestration in depleted oil and gas reservoirs is proposed by storing solar thermal energy in depleted oil and gas reservoirs in summer and extracting thermal energy for space heating in winter using CO2 as the working medium. A mathematical model of the energy storage and release process is established, and the thermal performance and CO2 sequestration performance of energy storage system in depleted oil and gas reservoirs are analysed. Results The results show that (1) the novel scheme has excellent thermal performance, with a single-well thermal extraction power of 4 808.95 kW, a thermal energy storage capacity of 49 859.21 GJ per heating season and an energy storage density of 28 984.23 kJ/m3. (2) The novel scheme has an energy recovery efficiency of 95.84% and a thermal recovery efficiency of 83.66% due to the strong sensitivity of the CO2 density to temperature. (3) The solubility trapping of CO2 in formation water is accelerated by the energy storage process. The periodic injection and extraction of CO2 during the process of energy storage and release causes the repeated expansion and contraction of the gas-water interface, which increases the gas-water contact area and improves the driving force of mass transfer, thus leading to an increase in CO2 dissolution in the formation water. Compared with the CO2 sequestration model alone, the mass ratio of CO2 dissolution in formation water for the energy storage model increases from 0.26% to 2.22%. Conclusion Overall, the novel scheme has excellent thermal performance. It accelerates CO2 geological sequestration and is a high-value scheme for depleted reservoir utilization and renewable energy space heating. It has great potential for wide application.
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