Modeling Near-Wellbore Tortuosity at Utah FORGE Site

Abstract

Near-wellbore tortuosity directly influences the flow efficiency between the wellbore and the rock matrix. The tortuosity-induced pressure drop elevates the injection pressure required for reservoir stimulation, as well as increasing the fluid circulation pressure during production, leading to high long-term energy consumption and operational costs. In this paper, we present a three-dimensional thermo-hydro-mechanical numerical model to investigate the hydraulic fracture propagation in the near-wellbore region. The study is based on the Stage 4 stimulation of Well 16A(78)-32 at the Utah FORGE site completed in 2024, which used a case-hole approach and slickwater as the fracturing fluid. The model takes a discrete element modeling approach and explicitly represents the well casing, cement sheath, and 36 perforation tunnels. This enables a detailed representation of the complex stress field resulting from the combined effects of subsurface in-situ stresses and stress concentrations around the wellbore and perforations. Furthermore, the model simulates the cooling effect on the stress field in the near-wellbore region, accounting for thermal responses within the casing-cement-perforation-rock structure. The simulation results highlight complex near-wellbore fracture growth phases, including fracture initiation, merging, longitudinal fracture growth, and transverse fracture growth. The predicted early-time bottomhole pressure from the simulation shows reasonable agreement with the field data within an acceptable range of deviation.