Experimental Investigation on the Evolution Mechanism of Deep Coal-rock Mechanical Properties Under Varying Temperature Conditions
1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China
2. Emergency Rescue Station, CNPC Haubei Oilfield Company, Erenhot 026000, China
| Abstract: | The drilling fluid in the wellbore would be in a state of continuous circulating flow during the drilling operation, and will undergo the compound heat exchange with the wellbore rock through the convection heat transfer and the heat conduction, causing the mechanical properties of the rock to change with the changing of its own temperature. To study the influence of the temperature changing on the borehole deformation, further enrich the theory of the wellbore stability guarantee and effectively ensure the wellbore stability of the deep coalbed methane (CBM) wells, a high-temperature, high-pressure rock triaxial mechanics testing system was used to test the evolution characteristics of various mechanical properties of deep coal-rock under different experimental temperature conditions (40°C-100°C). The results show that the higher the experimental temperature, the lower the stress value of the deep coal-rock when it fails. In the process of reaching peak strength, the higher the experimental temperature, the higher the proportion of plastic deformation of the deep coal-rock in its entire deformation stage. The compressive strength, elastic modulus, and main crack length of the deep coal-rock will decrease with the experimental temperature. The Poisson's ratio and the central fracture angle will increase with the experimental temperature. |
| Keywords: | Deep Coal-Rock; Mechanical Properties; Experimental Temperature; Evolution, Test |
| DOI: | 10.57237/j.jest.2022.01.001 |
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Received: 28 August 2022
Accepted: 14 October 2022
Published Online: 1 December 2022
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