@Article{fhmt.2026.081419,
AUTHOR = {Min Li, Haijun Luan, Ming Chi, Sen Chen, Yang Chen, Jiarui Cheng, Tian Xie, Rui Wang},
TITLE = {Experimental Study on the Critical Conditions for Hydrate Formation during CO<sub>2</sub> Driving Oil Recovery},
JOURNAL = {Frontiers in Heat and Mass Transfer},
VOLUME = {},
YEAR = {},
NUMBER = {},
PAGES = {{pages}},
URL = {http://www.techscience.com/fhmt/online/detail/26718},
ISSN = {2151-8629},
ABSTRACT = {This study used simulated formation water (15 g/L CaCl<sub>2</sub>) from a certain area of Xinjiang Oilfield as the experimental medium., and employed a high-pressure sealed reaction vessel and a sapphire window to systematically investigate the effects of water content (30%–70%), initial pressure (2–14 MPa), and the intervention of CH<sub>4</sub> on the critical point of CO<sub>2</sub> hydrate formation. The differences between the ‘visual confirmation’ method and the temperature-pressure curve inflection point method for determining hydrate formation were also compared. The study found that in a single CO<sub>2</sub> system under a constant pressure of 5 MPa and a water content of 30%–70%, no visible hydrate was observed with the naked eye. However, the inflection point method showed that the theoretical critical temperature and pressure increased with the increase in water content. For a 50% water content system, there was a threshold pressure range of 8–11 MPa. Only when the initial pressure was higher than this threshold would visible hydrates form, and the critical point shifted upward with the increase in pressure. In the CO<sub>2</sub>-CH<sub>4</sub> mixed system, the critical point under a constant pressure of 10 MPa showed a V-shaped trend with changes in gas ratio, with a minimum point at a 1:1 ratio; the constant ratio and variable pressure experiment indicated that the intervention of CH<sub>4</sub> significantly increased the critical temperature and pressure. Furthermore, the introduction of CH<sub>4</sub> changed the growth position of hydrates, shifting them from the gas-liquid interface to the liquid phase matrix. The study revealed the pressure threshold effect of CO<sub>2</sub> hydrate formation in high mineralization degree formation water systems and the gas component competition mechanism: when the ratio of the two components is balanced, the competitive effect is minimized, forming the optimal formation conditions; as the proportion of CH<sub>4</sub> increases, its competitive advantage strengthens, not only increasing the critical temperature and pressure, but also driving the shift of the hydrate growth position, demonstrating the decisive regulatory role of gas components on the equilibrium and formation kinetics of hydrates, providing experimental basis for the risk prevention of hydrates in the CO<sub>2</sub> flooding process.},
DOI = {10.32604/fhmt.2026.081419}
}