|
|
|
| Experimental investigation on the permeability of gypsum rock under temperature-stress coupling |
| ZHANG Qiangxing，LIU Jianfeng，ZENG Yin，LIAO Yilin，XU Deng，ZHU Anqi |
| (State Key Laboratory of Hydraulic and Mountain River Engineering，Sichuan University，Chengdu，Sichuan 610065，China) |
|
|
|
|
Abstract In order to study the gas tightness characteristics of gypsum rock as cap rock in energy storage in the deep rock environment，the modified THM coupling triaxial rock permeability test platform based on the MTS 815 rock mechanics test system of Sichuan University was used to perform gas permeability tests of gypsum rock under different temperatures and confining pressures for the first time in China. The test results show that the gypsum rock in the natural state with a permeability ranging between 10－17–10－15 m2 can be classified to the dense low permeability rock medium. At the same temperature，the stress-strain curve of the gypsum rock has a brittle-ductile transition characteristic with increasing the confining pressure，and at the same time the peak stress of the gypsum rock increases continuously. Under the same confining pressure，with increasing the temperature，gypsum samples show thermal damage and thermal softening effects，in other words，the peak stress reduces gradually and the plastic deformation ability increases. The initial permeability of the gypsum rock decreases in an exponential function with increasing the confining pressure. The initial permeability of the gypsum rock under the confining pressure of 5 MPa is 4.13×10－17 m2，while under the confining pressure of 15，25 and 35 MPa，the initial permeability decreases by 37.23%，65.86% and 75.79%，respectively. Under different temperature- mechanics coupling conditions，the permeability of the gypsum rock shows a similar decrease-increase trend，and the overall permeability level of the rock decreases with increasing the temperature or the confining pressure.
|
|
|
|
|
|
|
|
|
2019, Vol. 38 
