Evaluation of Thermophysical and Mechanical Properties of Sandstone Due to High-Temperature |
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Authors: | Zhen Dong Yanpeng Chen Xinggang Wang Lingfeng Kong Lianguo Wang Xinning Li Fenjin Sun Ke Ding Hanqi Wu Shanshan Chen Mengyuan Zhang |
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Affiliation: | 1.Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, China;2.Research Institute of Petroleum Exploration & Development, PetroChina Tuha Oilfield Company, Hami 839009, China;3.Petrochina Planning Department, Beijing 100024, China;4.State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, China;5.Petrochina Gas Storage Company, Beijing 100101, China |
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Abstract: | In this study, thermophysical and mechanical tests were conducted on sandstone samples from room temperature to 1000 °C. Based on the test results, the thermophysical properties (such as specific heat capacity, thermal conductivity, and thermal expansion coefficient) of sandstone after high-temperature treatment and the variations of mechanical properties (including peak strength, peak strain, elastic modulus, and whole stress-strain curve) with temperature were analyzed. Indeed, the deterioration law of sandstone after high-temperature treatment was also explored with the aid of a scanning electron microscope (SEM). The results show that with the increase in temperature, the specific heat capacity and thermal expansion coefficient of sandstone samples after high-temperature treatment increase first and then decrease, while the thermal conductivity gradually decreases. The range from room temperature to 1000 °C witnesses the following changes: As temperature rises, the peak strength of sandstone rises initially and falls subsequently; the elastic modulus drops; the peak strain increases at an accelerated rate. Temperature change has a significant effect on the deterioration rules of sandstone, and the increase in temperature contributes to the transition in the failure mode of sandstone from brittle failure to ductile failure. The experimental study on the thermophysical and mechanical properties of sandstone under the action of high temperature and overburden pressure has a guiding significance for the site selection and safety evaluation of UCG projects. |
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Keywords: | underground coal gasification high-temperature sandstone thermophysical properties mechanical properties microstructure |
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