Assessing the performance of multi-perforation fracturing for deep geothermal energy development: insights from THMD modeling

Abstract Multi-perforation fracturing, despite its proven efficiency in unconventional oil and gas formations, remains rarely assessed for geothermal reservoir applications. Here, we systematically compared simultaneous fracturing (SMF) and sequential fracturing (SQF) using our newly established two-dimensional thermo-hydro-mechanical-damage (THMD) coupled numerical platform, quantifying fluid partitioning among multi-perforations and thermal stress effects. The analysis focused on fracture propagation behavior and multi-physical field evolution under varying dimensionless perforation spacings (DPS), defined as the ratio of perforation spacing to perforation length. Results revealed that SMF creates external fractures deviating 9–18° from the maximum principal direction, and the internal fracture requires higher initiation pressures and receives less fluid. In SQF, subsequent fractures deflect toward previous ones at DPS 3.3 but propagate along straight paths at DPS 6.7 and 10, with initiation pressures progressively increasing due to cumulative stress shadowing. Regarding multi-physical field evolution, the minimum principal stress transitions from compression to tension within fractures and near fracture tips. The internal fracture in SMF and subsequent fractures in SQF both exhibit higher pore pressure and lower temperature. Thermal stress primarily facilitates fracture development by reducing initiation pressure by approximately 5–8 MPa under the present conditions, while fluid pressure dominates fracture propagation. These findings provide fundamental insights for fracture network optimization and geothermal reservoir stimulation.