Assess Impacts of Well Configuration and Boundary on CO2-based Geothermal Production Using Response Surface Models

Geothermal harvest by using sequestered CO₂ in underground reservoirs as the working fluid is an effective approach to reduce CO₂ emission and fossil energy consumption. The integrated impact of reservoir boundary conditions, well placement and operations on this CO₂ geothermal production (CGP) is unclear. This study aims to analyse these influences continuously in a multi-dimensional parameter space, not just several scenarios in the previous studies. A total 200 samples are drawn from a 6-D input parameter space using Latin-Hypercube sampling method. A suite of numerical CGP reservoir models is constructed using the 200 input samples and executed. Five performance outputs are defined and calculated from the simulation results. Response surface (RS) models for each output are developed based on the 200 input-output dataset. Using the fast RS models, sensitivity indices of each output to each input are efficiently calculated to screen sensitive parameters. Pairwise RSs are visualized for evaluation of the impacts of the sensitive inputs on each output. The results show well space is the controlling parameters of the system. Overpressure positively affects CO₂ circulation and storage, and heat recovery. Longer horizontal well perforation lengths can enhance CO₂ circulation. Boundary conditions won't affect the system performance except the Y lateral boundaries, which show a positive impact on CO₂ storage.