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Numerical Simulation of Methane Production from Hydrates Induced by Different Depressurizing Approaches
Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian 116023, China
College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, China
* Author to whom correspondence should be addressed.
Received: 23 December 2011; in revised form: 13 February 2012 / Accepted: 17 February 2012 / Published: 22 February 2012
Abstract: Several studies have demonstrated that methane production from hydrate-bearing porous media by means of depressurization-induced dissociation can be a promising technique. In this study, a 2D axisymmetric model for simulating the gas production from hydrates by depressurization is developed to investigate the gas production behavior with different depressurizing approaches. The simulation results showed that the depressurization process with depressurizing range has significant influence on the final gas production. On the contrary, the depressurizing rate only affects the production lifetime. More amount of cumulative gas can be produced with a larger depressurization range or lowering the depressurizing rate for a certain depressurizing range. Through the comparison of the combined depressurization modes, the Class 2 (all the hydrate dissociation simulations are performed by reducing the initial system pressure with the same depressurizing range initially, then to continue the depressurization process conducted by different depressurizing rates and complete when the system pressure decreases to the atmospheric pressure) is much superior to the Class 1 (different depressurizing ranges are adopted in the initial period of the gas production process, when the pressure is reduced to the corresponding value of depressurization process at the different depressurizing range, the simulations are conducted at a certain depressurizing rate until the pressure reaches the atmospheric pressure) for a long and stable gas production process. The parameter analysis indicated that the gas production performance decreases and the period of stable production increases with the initial pressure for the case of depressurizing range. Additionally, for the case of depressurizing range, the better gas production performance is associated with higher ambient temperature for production process, and the effect of thermal conductivity on gas production performance can be negligible. However, for the case of depressurizing rate, the ambient temperature or thermal conductivity is dominant in different period of gas production process.
Keywords: methane hydrate; numerical simulation; depressurizing range; depressurizing rate
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MDPI and ACS Style
Ruan, X.; Song, Y.; Zhao, J.; Liang, H.; Yang, M.; Li, Y. Numerical Simulation of Methane Production from Hydrates Induced by Different Depressurizing Approaches. Energies 2012, 5, 438-458.
Ruan X, Song Y, Zhao J, Liang H, Yang M, Li Y. Numerical Simulation of Methane Production from Hydrates Induced by Different Depressurizing Approaches. Energies. 2012; 5(2):438-458.
Ruan, Xuke; Song, Yongchen; Zhao, Jiafei; Liang, Haifeng; Yang, Mingjun; Li, Yanghui. 2012. "Numerical Simulation of Methane Production from Hydrates Induced by Different Depressurizing Approaches." Energies 5, no. 2: 438-458.