Identification of Fracture Flow Pathways at Utah FORGE Following Stimulation Activities in 2022 and 2024

Abstract

A comprehensive update to the Reference Discrete Fracture Network (DFN) model for the Frontier Observatory for Research in Geothermal Energy (FORGE) site near Milford, Utah, has been completed. This revision was informed by the identification of flow pathways between wells 16A(78)-32 and 16B(78)-32 following stimulation activities conducted in 2022 and 2024. Designated as the Utah FORGE 2025 v1 DFN, the revised model includes 131 discrete planar fractures with radius values ranging from 14 to 780 m and 19,544 stochastic fractures located away from well control with radius values ranging from 20 to 149 m. Discrete fractures in the DFN were identified using updated microearthquake data from surface arrays and deep geophones, fracture interpretations from FMI and UBI logs (with aperture estimates when available), k-means cluster rock type analysis from various well logs, frac hit data, and core samples. This paper describes the methodology used for mapping fracture pathways in the reservoir. While fracture geometry is detailed in the revised DFN model, hydraulic properties are not assigned. Notably, natural fractures primarily account for the observed stimulated flow in this model, with just a few induced hydraulic fractures added to connect the natural fracture pathways to some well casing perforation intervals.