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Energies 2017, 10(12), 2078; doi:10.3390/en10122078

Experimental Study on the Mechanical Properties of CH4 and CO2 Hydrate Remodeling Cores in Qilian Mountain

Key Laboratory of Ocean Energy Utilization and Energy Conservation of the Ministry of Education, Dalian University of Technology, Dalian 116024, China
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Received: 12 October 2017 / Revised: 3 December 2017 / Accepted: 4 December 2017 / Published: 7 December 2017
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Abstract

The CH4-CO2 replacement method has attracted global attention as a new promising method for methane hydrate exploitation. In the replacement process, the mechanical stabilities of CH4 and CO2 hydrate-bearing sediments have become problems requiring attention. In this paper, considering the hydrate characteristics and burial conditions of hydrate-bearing cores, sediments matrices were formed by a mixture of kaolin clay and quartz sand, and an experimental study was focused on the failure strength of CH4 and CO2 hydrate-bearing sediments under different conditions to verify the mechanical reliability of CH4-CO2 replacement in permafrost-associated natural gas deposits. A series of triaxial shear tests were conducted on the CH4 and CO2 hydrate-bearing sediments under temperatures of −20, −10, and −5 °C, confining pressures of 2.5, 3.75, 5, 7.5, and 10 MPa, and a strain rate of 1.0 mm/min. The results indicated that the failure strength of the CO2 hydrate-bearing sediments was higher than that of the CH4 hydrate-bearing sediments under different confining pressures and temperatures; the failure strength of the CH4 and CO2 hydrate-bearing sediments increased with an increase in confining pressure at a low confining pressure state. Besides that, the failure strength of all hydrate-bearing sediments decreased with an increase in temperature; all the failure strengths of the CO2 hydrate-bearing sediments were higher than those of the CH4 hydrate-bearing sediments in different sediment matrices. The experiments proved that the hydrate-bearing sediments would be more stable than that before CH4-CO2 replacement. View Full-Text
Keywords: CH4-CO2 replacement; hydrate-bearing sediments; remodeling cores; stress-strain curves; failure strength; cohesion force CH4-CO2 replacement; hydrate-bearing sediments; remodeling cores; stress-strain curves; failure strength; cohesion force
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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. (CC BY 4.0).

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MDPI and ACS Style

Luo, T.; Li, Y.; Liu, W.; Sun, X.; Shen, S. Experimental Study on the Mechanical Properties of CH4 and CO2 Hydrate Remodeling Cores in Qilian Mountain. Energies 2017, 10, 2078.

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