College of Earth Sciences, Jilin University, Changchun 130061, China

For the in-situ gas-injection mining technology of oil shale by process, a numerical simulation method with flow-thermo-solid coupling is proposed in this paper. This method adopts separate simulations and step-by-step coupling simulation ideas combined with the advantages of the finite element method and the finite volume method. The numerical simulation of flow-thermo-solid coupling is decomposed into two parts:flow-solid coupling and thermo-solid coupling. Considering the Fuyu oil shale in-situ production test area in Songliao Basin as an example, it is concluded that the oil shale has undergone four heating stages:a rapid temperature rise, a steady temperature rise, a slow temperature rise, and heat preservation. It takes about 10 years for the stress-strain state of the oil shale layer to reach a steady-state through the thermo-solid coupling. The main strain zones of the oil shale layer are distributed near the fracturing fractures connected to the gas injection well and at the edge of the fracturing fractures. The areas with the plastic deformation in the oil shale layer predominantly appear near the gas injection wells, production wells, and fracturing channels. The areas with the largest fracture strength are mostly distributed near the edge of the fracturing fractures with low flow velocity and low temperature.