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Formation and Dissociation of Methane Hydrates from Seawater in Consolidated Sand: Mimicking Methane Hydrate Dynamics beneath the Seafloor
Energies 2013, 6(12), 6242-6254; doi:10.3390/en6126242
Article

Evaluation of Different CH4-CO2 Replacement Processes in Hydrate-Bearing Sediments by Measuring P-Wave Velocity

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Received: 27 September 2013 / Revised: 14 November 2013 / Accepted: 15 November 2013 / Published: 28 November 2013
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Abstract

The replacement of methane with carbon dioxide in natural gas hydrate-bearing sediments is considered a promising technology for simultaneously recovering natural gas and entrapping CO2. During the CH4-CO2 replacement process, the variations of geophysical property of the hydrate reservoir need to be adequately known. Since the acoustic wave velocity is an important geophysical property, in this work, the variations of P-wave velocity of hydrate-bearing sediments were measured during different CH4-CO2 replacement processes using pure gaseous CO2 and CO2/N2 gas mixtures. Our experimental results show that P-wave velocity continually decreased during all replacement processes. Compared with injecting pure gaseous CO2, injection of CO2/N2 mixture can promote the replacement process, however, it is found that the sediment experiences a loss of stiffness during the replacement process, especially when using CO2/N2 gas mixtures.
Keywords: gas hydrate; CH4-CO2 replacement; P-wave velocity gas hydrate; CH4-CO2 replacement; P-wave velocity
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Liu, B.; Pan, H.; Wang, X.; Li, F.; Sun, C.; Chen, G. Evaluation of Different CH4-CO2 Replacement Processes in Hydrate-Bearing Sediments by Measuring P-Wave Velocity. Energies 2013, 6, 6242-6254.

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