Phase equilibrium law of CO2 storage in depleted gas reservoirs
In the process of CO2 injection and storage of a single well in depleted gas reservoirs, the injected CO2 causes the rebalance among gas, water and solid, and the accompanying CO2 dissolution, water evaporation and salting out affect the physical properties of the formation near this well. Therefore...
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| Format: | Article |
| Language: | zho |
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Editorial Department of Petroleum Reservoir Evaluation and Development
2023-06-01
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| Series: | Youqicang pingjia yu kaifa |
| Subjects: | |
| Online Access: | https://red.magtech.org.cn/fileup/2095-1426/PDF/1687763513315-1765805370.pdf |
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| Summary: | In the process of CO2 injection and storage of a single well in depleted gas reservoirs, the injected CO2 causes the rebalance among gas, water and solid, and the accompanying CO2 dissolution, water evaporation and salting out affect the physical properties of the formation near this well. Therefore, taking depleted gas reservoir in western Sichuan as an example, the SRK-HV equation and salting out model are used to analyze the three-phase change rule during the CO2 injection process of the depleted gas reservoir. The researches show that during the CO2 injection process in the constant volume system, with the increase of the number of mole of CO2, the gas phase pressure increases, the CO2 solubility gradually increases, and the mole fraction of H2O in the gas phase gradually decreases, but the total number of mole of H2O in the gas phase continuously increases, indicating that the total evaporation of water increases. In addition, the water phase volume reduction caused by water evaporation is smaller than the initial water phase volume, so the increase of formation water salinity is small. The dissolution of CO2 accelerates the precipitation of CaCO3, while inhibiting the precipitation of CaSO4 and CaSO4·2H2O. In calcium chloride type formation water, CaCO3 and CaSO4 will be separated with the increase of salinity. The research results has certain reference significance for the study of water evaporation and salting out during CO2 injection in depleted gas reservoirs. |
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| ISSN: | 2095-1426 |