Abstract Enhanced geothermal systems (EGS) are engineered reservoirs that have been stimulated to extract efficiently heat from low permeability hot rock. Generating efficient hydraulic pathways for heat exchange is crucial. A 3-dimensional Discrete Fracture Network (DFN) model was developed for simulating and determining the optimum hydraulic fracture network for the proposed Phase 3 injection and production wells at a Frontier Observatory for Research in Geothermal Energy (FORGE) site in Utah. Numerical simulations are used to study hydrogeothermal transport in the fractured media. The effect natural fractures contribute to hydraulic fracture growth were studied in regard to changes in natural fracture intensity, flow rate, hydraulic pathways, permeability, and perforation cluster spacing. Post hydraulic fracturing networks are incorporated into a hydrothermal modeling package where a possible range of heat extraction values are determined from the reservoir over a 30-year production period. Results suggest that DFN modeling in an EGS setting has exceptional value. The study serves as a benchmark for developing an improved understanding of the effects of the existing FORGE natural fracture systems. The simulations suggest an optimized pumping schedule that generates conductive post-stimulation fracture networks between hypothetical Phase 3 injection and production wells and establishes an effective hydrological thermal model under various fluid flow conditions. A more viscous fluid increases the fracture height and significantly effects fracture growth in the middle cluster. Injection temperature and flow rate are two of most important parameters that control the production temperature and heat recovery.

中文翻译：

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Utah FORGE：基于花岗岩的离散裂缝网络的水地热建模

摘要 增强型地热系统 (EGS) 是经过改造的工程储层，可有效地从低渗透性热岩中提取热量。为热交换生成有效的水力通路至关重要。开发了一个 3 维离散裂缝网络 (DFN) 模型，用于模拟和确定犹他州地热能研究前沿观测站 (FORGE) 站点拟建的第 3 阶段注入和生产井的最佳水力压裂网络。数值模拟用于研究裂缝介质中的水地热输运。研究了天然裂缝对水力裂缝生长的影响，包括天然裂缝强度、流速、水力路径、渗透率和射孔簇间距的变化。后水力压裂网络被整合到一个热液建模包中，其中在 30 年的生产期内从储层中确定了可能的热提取值范围。结果表明，EGS 环境中的 DFN 建模具有非凡的价值。该研究为更好地了解现有 FORGE 天然裂缝系统的影响提供了基准。模拟提出了优化的泵送计划，可在假设的第 3 阶段注入井和生产井之间生成导电的增产后裂缝网络，并在各种流体流动条件下建立有效的水文热模型。更粘稠的流体会增加裂缝高度并显着影响中间簇的裂缝生长。