Effect of real-time temperature and shear angle on the mechanical strength and energy evolution of oil shale
Siqi Ren,
Lei Wang,
Dong Yang,
Zhiqin Kang,
Pengyu Zhang
Affiliations
Siqi Ren
Key Laboratory of In-situ Property Improving Mining of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, P. R. China
Lei Wang
Key Laboratory of In-situ Property Improving Mining of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, P.R. China; The In-situ Steam Injection Branch of State Center for Research and Development of Oil Shale Exploitation, Taiyuan University of Technology, Taiyuan 030024, P.R. China
Dong Yang
Key Lab of In-situ Property-improving Mining of Ministry of Education, Taiyuan University of Technology, Taiyuan, China 030024
Zhiqin Kang
Key Lab of In-situ Property-improving Mining of Ministry of Education, Taiyuan University of Technology, Taiyuan, China 030024
Pengyu Zhang
Key Laboratory of In-situ Property Improving Mining of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, P. R. China; School of Safety and Emergency Management Engineering, Taiyuan University of Technology, Jinzhong, 030600, P. R. China
During in situ thermal injection in oil shale mining, the shear properties of oil shale at real-time high temperatures considerably affect the stability of injection and production wellbore as well as oil and gas production. The results of this study show that the shear strength and modulus of oil shale decrease with an increase in the shear angle at real-time high temperatures. With increasing temperature, the shear strength and modulus first decrease and then increase, reaching their lowest values at 400 °C. Thereafter, at temperatures above 400 °C, the energy accumulated in the elasticity and crack propagation stages is released and a large amount of energy is liberated during the instability failure. Finally, with rising temperature, the failure stage of oil shale changes from brittle to ductile, secondary fractures gradually increase and the failure characteristics step-by-step turn from through to nonthrough cracking characteristics.
