Experimental Study on the Mechanical Properties of CH 4 and CO 2 Hydrate Remodeling Cores in Qilian Mountain
The CH 4 -CO 2 replacement method has attracted global attention as a new promising method for methane hydrate exploitation. In the replacement process, the mechanical stabilities of CH 4 and CO 2 hydrate-bearing sediments have become problems requiring attention. In this paper, considering the hydr...
| Main Authors: | , , , , |
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| Format: | Article in Journal/Newspaper |
| Language: | unknown |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1996-1073/10/12/2078/pdf https://www.mdpi.com/1996-1073/10/12/2078/ |
| Summary: | The CH 4 -CO 2 replacement method has attracted global attention as a new promising method for methane hydrate exploitation. In the replacement process, the mechanical stabilities of CH 4 and CO 2 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 CH 4 and CO 2 hydrate-bearing sediments under different conditions to verify the mechanical reliability of CH 4 -CO 2 replacement in permafrost-associated natural gas deposits. A series of triaxial shear tests were conducted on the CH 4 and CO 2 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 CO 2 hydrate-bearing sediments was higher than that of the CH 4 hydrate-bearing sediments under different confining pressures and temperatures; the failure strength of the CH 4 and CO 2 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 CO 2 hydrate-bearing sediments were higher than those of the CH 4 hydrate-bearing sediments in different sediment matrices. The experiments proved that the hydrate-bearing sediments would be more stable than that before CH 4 -CO 2 replacement. CH 4 -CO 2 replacement; hydrate-bearing sediments; remodeling cores; stress-strain curves; failure strength; cohesion force |
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