Stanford Geothermal WorkshopFebruary 9-11, 2026

Geothermal energy is a readily dispatchable energy source, unlike intermittent renewable energy such as wind and solar, and represents a vital component of a sustainable energy strategy. In Enhanced Geothermal Systems (EGS), hydraulic stimulation creates new fractures and enhances natural ones, enabling heat extraction from formations with limited inherent permeability and working fluids. Because fluid flow in EGS is largely confined to fractures, characterization of fracture properties using dynamic field data is crucial for reliable performance prediction. We propose a novel and rapid streamline-based inversion framework for fracture characterization in EGS. In this paper, the streamline-based technology, well established in the oil and gas industry, is tailored for EGS applications and introduced for geothermal systems. The proposed framework integrates distributed temperature sensing (DTS) and cluster-level distributed flow rate measurements to calibrate fracture properties. The concept of thermal tracer travel time is utilized to integrate DTS data, while the conventional streamline time of flight is applied to cluster-wise flow rate data. Visualization of thermal tracer travel time provides detailed insight into thermal front propagation behavior and thermal breakthrough time which are key indicators for EGS performance assessment. The streamline-based fracture parameter sensitivities can be computed analytically from a single forward simulation, substantially reducing the computational burden of gradient-based minimization of data misfit during history matching process. The proposed framework is first validated on a synthetic EGS model with DTS and cluster-level production rate measurements. Subsequently, it is applied to the Utah FORGE site using data from a month-long circulation test conducted in August 2024. In both the synthetic and actual field applications, the proposed approach achieved successful history matching through fracture characterization with high computational efficiency. For the Utah FORGE case, the history matching was carried out in approximately one day with 25 iterations and each iteration requiring a single forward simulation. These results demonstrate that streamline-based technology provides a powerful and efficient tool for fracture characterization and visualization of thermal front propagation in EGS.

Topic: Modeling