Anisotropy in Thermal Recovery of Oil ShalePart 1: Thermal Conductivity, Wave Velocity and Crack Propagation

In this paper, the evolution of thermal conductivity, wave velocity and microscopic crack propagation both parallel and perpendicular to the bedding plane in anisotropic rock oil shale were studied at temperatures ranging from room temperature to 600 degrees C. The results show that the thermal conductivity of the perpendicular to bedding direction (K-PER) (PER: perpendicular to beeding direction), wave velocity of perpendicular to bedding diretion (V-PER), thermal conduction coefficient of parallel to beeding direction (K-PAR) and wave velocity of parallel to beeding direction (V-PAR) (PAR: parallel to bedding direction) decreased with the increase in temperature, but the rates are different. K-PER and V-PER linearly decreased with increasing temperature from room temperature to 350 degrees C, with an obvious decrease at 400 degrees C corresponding to a large number of cracks generated along the bedding direction. K-PER, V-PER, K-PAR and V-PAR generally maintained fixed values from 500 degrees C to 600 degrees C. 400 degrees C has been identified as the threshold temperature for anisotropic evolution of oil shale thermal physics. In addition, the relationship between the thermal conductivity and wave velocity based on the anisotropy of oil shale was fitted using linear regression. The research in this paper can provide reference for the efficient thermal recovery of oil shale, thermal recovery of heavy oil reservoirs and the thermodynamic engineering in other sedimentary rocks.