Replacement of Methane from Quartz Sand-Bearing Hydrate with Carbon Dioxide-in-Water Emulsion

The replacement of CH 4 from its hydrate in quartz sand with 90:10, 70:30, and 50:50 ( w CO 2: w H 2 O ) carbon dioxide-in-water (C/W) emulsions and liquid CO 2 has been performed in a cell with size of ϕ 36 × 200 mm. The above emulsions were formed in a new emulsifier, in which the temperature and pressure were 285.2 K and 30 MPa, respectively, and the emulsions were stable for 7–12 h. The results of replacing showed that 13.1–27.1%, 14.1–25.5%, and 14.6–24.3% of CH 4 had been displaced from its hydrate with the above emulsions after 24–96 h of replacement, corresponding to about 1.5 times the CH 4 replaced with high-pressure liquid CO 2 . The results also showed that the replacement rate of CH 4 with the above emulsions and liquid CO 2 decreased from 0.543, 0.587, 0.608, and 0.348 1/h to 0.083, 0.077, 0.069, and 0.063 1/h with the replacement time increased from 24 to 96 h. It has been indicated by this study that the use of CO 2 emulsions is advantageous compared to the use of liquid CO 2 in replacing CH 4 from its hydrate.