## 2 Literature Review
The study observed that at 120 \({}^{\circ}\)C, the resin layer melted, causing the proppants to adhere to one another and compress flow channels, leading to reduced permeability. Ref. [35] investigated sintered bauxite ceramic proppants at 130 \({}^{\circ}\)C under normal closure stresses of up to 60 MPa for 60 h. The study provided direct evidence of proppant dissolution, crushing, and embedment through stress-cycle plastic deformation measurements, hydraulic conductivity analysis, and post-test SEM imaging. Effluent chemical analysis confirmed significant geochemical interactions under these conditions. While most of the reviewed studies have investigated the performance of proppants under coupled THMC conditions, the specific geochemical interactions between proppants and geothermal fluids remain insufficiently resolved. This study isolates thermo-chemical processes under static conditions without applied stress, to evaluate chemical reactivity independent of mechanical factors. While EGS conditions include closure stress, decoupling allows a clearer understanding of resin degradation and precipitation mechanisms. Moreover, few investigations have employed multi-scale analytical techniques to isolate and quantify chemical degradation mechanisms independent of mechanical effects, an essential step toward understanding failure pathways and advancing the development of chemically inert proppant materials for geothermal applications. This study addresses this gap by systematically evaluating the geochemical stability and surface reactivity of commercially available proppants (coated and uncoated) under controlled geothermal conditions. The experiments focus exclusively on fluid-proppant chemical interactions over 25 days at 130 \({}^{\circ}\)C, incorporating thermal cycling to simulate EGS operations. The 25-day duration was chosen to capture early to intermediate stages of proppant-fluid interactions. A temperature of 130 \({}^{\circ}\)C was selected to evaluate proppant reactivity at the lower threshold of EGS-relevant conditions and to align with previous studies that documented notable proppant degradation and geochemical alteration within this temperature range [21; 22; 28]. It represents a critical threshold where resin softening and ion exchange reactions begin to manifest, enabling targeted evaluation of chemical stability without the confounding effects of extreme thermal or mechanical stress. In addition, site-specific geothermal working fluids (which were later diluted as explained in the Methodology) were sourced from the Utah FORGE project to ensure that experimental conditions accurately reflected in-situ geochemical environments. Scanning Electron Microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), and micro-computed tomography (micro-CT) techniques are used to evaluate chemical degradation processes. This research aims to decouple chemical degradation processes from mechanical effects and to provide a clearer understanding of proppant reactivity, coating behavior, and long-term compatibility with low-temperature geothermal fluids. This article is a revised and expanded version of a paper entitled \"Geochemical Interactions of Proppants with Utah FORGE Fluids: Insights from Moderate-Temperature Experiments\", which was presented at the 59 th U.S. Rock Mechanics/Geomechanics Symposium (ARMA), Santa Fe, NM, USA, 8-11 June 2025 [36].