[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 ther-mal energy in depleted oil and gas reservoirs in summer and extracting thermal energy for space heating in winter u-sing 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 recov-ery efficiency of 95.84％and a thermal recovery efficiency of 83.66％due to the strong sensitivity of the CO2 densi-ty 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 re-peated expansion and contraction of the gas-water interface,which increases the gas-water contact area and im-proves 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 ener-gy 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.
关键词
枯竭油气藏/太阳能跨季节储热/可再生能源供暖/CO2封存/地热太阳能联合供暖/储热供暖
Key words
depleted oil and gas reservoir/seasonal solar thermal energy storage/renewable energy space heating/CO2 sequestration/conjugated heating system of geothermal and solar energy/thermal energy storage for space heat-ing
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