3D Modeling of the Utah Forge Reservoir Stimulation with Proppant Transport and Deposition

Abstract

Abstract The paper presents 3D modeling and analysis of hydraulic stimulations conducted at the DOE Utah FORGE EGS site. We simulated the Stage-3 field stimulation along with proppant transport and deposition and examined the injection pressure history, produced fracture geometry, and potential stimulated reservoir volume. For the hydraulic and natural fracture propagation and interactions, we used our state-of-the-art simulator model. The solid rock and fracture surface mechanical deformation are simulated using the boundary element method, the fluid flow inside the fracture is model using the finite element method, and the fracture propagation is implemented in the framework of the linear elastic fracture mechanics, whereas the proppant transport and deposition implement using cell-centric finite volume method. The findings show that asymmetric height growth is expected under the stress regimes and lithology often found in EGS and that rock mass discontinuities such preexisting fractures, rock anisotropy, and lithological boundaries might impede height growth. The results in Utah FORGE's Stage-3 stimulation seems to indicate upward growth and interaction with natural fractures that result in a moderately complicated stimulated reservoir volume (SRV) with an HF/NF network. The transport and deposition of proppant in geothermal reservoirs are significantly impacted by thermal impacts, according to numerical calculations. High temperature can accelerate proppant settling as it greatly reduces the viscosity of the fracturing fluid. Low viscosity fracturing fluids, like slick water, can cause a narrow, propped fracture network and very severe proppant settlement near the injection point in geothermal reservoir stimulation. The findings show that because micro-proppants are smaller size particles, they tend to be carried into complex HF/NF networks, potentially increasing their conductivity, and facilitating heat circulation path in the EGS reservoir.