A New Method for Enhanced Production of Gas Hydrate with CO2

• Main Authors: B. P. Mcgrail, T. Zhu, R. B. Hunter, M. D. White, S. L. Patil, A. S. Kulkarni
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2004
• Subjects: Canada; Mackenzie Delta; Northwest Territories; Methane hydrate
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.634.8460; http://www.searchanddiscovery.com/documents/abstracts/2004hedberg_vancouver/extended/mcgrail/images/mcgrail.pdf

Presently, depressurization, thermal stimulation, inhibitor injection, or a combination of these methods have been considered as possible means of gas hydrate production. Depressuriza-tion is the most often considered method for commercial production of hydrates (SLOAN, 1998), but combined depressurization and thermal stimulation have been used recently to produce a small amount of gas from the Mallik 5L-38 research well located on the Mackenzie delta, Northwest Territories, Canada. Additional studies are needed to ascertain the economic viability of any of these methods for commercial production of gas hydrates. Another method that has been discussed for gas hydrate production involves the injection of CO2. The idea of swapping CO2 for CH4 in gas hydrates was first advanced by Ohgaki et al. (1996) and then for ethane hydrate by Nakano et al. (1998). Their concept involves injecting CO2 gas, which is then allowed to equilibrate with methane hydrate along the three-phase equilibrium boundary (SMITH et al., 2001). Because of the difference in chemical affinity for CO2 versus methane in the sI hydrate structure, the mole fraction of methane would be reduced to approxi-mately 0.48 in the hydrate and rise to a value of 0.7 in the gas phase at equilibrium. However, neither Ohgaki et al. (1996) or Nakano et al. (1998) addressed the important issue of the kinetics