Effect of thermal cycling on mechanical properties and energy evolution of sandstone

In geothermal energy exploration, the reservoir rock is always subjected to thermal cycles and its physical properties will be seriously affected. In this paper, the changes of the internal structure of the sandstone after the thermal cycle are firstly evaluated by ultrasonic tests. Then, uniaxial compression tests are conducted on the treated specimens. The effects of the thermal cycling on mechanical properties and energy evolution law of the sandstone are analyzed. The results show that the density, P-wave velocity and mechanical properties of the sandstone reduced with the increase in the thermal cycle, especially in the high temperature cycle. The increase of the temperature in the thermal cycle can increase the influence of the thermal cycle on the energy evolution law.