Production performance of oil shale in-situ conversion with multilateral wells

A novel method using multilateral wells to perform oil shale in-situ conversion process is proposed in this paper. This method constructs radial branches in upper and lower oil shale formation as injection and production wells. Hot fluids are injected from the injection wells, and pyrolyzed oil and gas are extracted by production wells. In this study, a 3D transient model coupling fluid flow, heat transfer and chemical process is established and implemented on COMSOL Multiphysics platform to investigate the oil shale in-situ conversion process. The temperature field, production characteristics and energy performance are characterized. Sensitivity of oil shale properties and operational parameters are analyzed. Influences of multilateral-well arrangements are studied. The simulation results indicate that the products are strongly dependent to oil shale temperature. The specific heat capacity, injection fluid temperature and injection mass flow rate can significantly influence production performance, while thermal conductivity has negligible effect. Multilateral wells with 5 branches, 60° branch angle and 40 m branch length show the best production performance among the computational cases. This study provides comprehensive insights and suggestions for the application of multilateral wells in oil shale in-situ conversion process.