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Experimental Study on the Effect of Pressure on the Replacement Process of CO2–CH4 Hydrate below the Freezing Point

Zhang, Xuemin, Li, Yang, Yao, Ze, Li, Jinping, Wu, Qingbai, Wang, Yingmei
Energy & fuels 2018 v.32 no.1 pp. 646-650
carbon dioxide, freezing point, ice, methane, methane production, natural gas, particle size, permafrost, temperature
The recovery of natural gas from CH₄ hydrate deposits in permafrost environments through injection of CO₂ is considered to be a suitable strategy for CH₄ production and CO₂ storage. To study the replacement characteristics of CO₂–CH₄ hydrate below the freezing point, the experiment was conducted in ice powder with particle size of 800 μm at different injection pressures (3.6, 4.0, and 4.5 MPa) of CO₂. The experimental results showed that the average replacement rate and efficiency increased with the increasing of injected pressure of CO₂ gas. Also, the average replacement rate and efficiency reached up to 0.403 mmol/h and 13.20% when the injected pressure of CO₂ was at 4.5 MPa. The results also indicated that, compared with the temperature conditions above the freezing point, the replacement rate of CO₂–CH₄ hydrate was slow below the freezing point. These results provide a theoretical guidance for gas production from methane hydrate using CO₂–CH₄ replacement method in permafrost region in the future.