Geochemical Interactions of Proppants with Utah FORGE Fluids: Insights from Moderate-Temperature Experiments

ABSTRACT: This study investigates the geochemical interactions between various proppant materials and geothermal fluids from the Utah FORGE site under controlled experimental conditions at 13°C, for 25 days, implementing crushed and as received proppants. Four distinct proppant types were evaluated: white sand, brown sand, resin-coated sand, and ultra-low-density (ULD) ceramic proppant. Geochemical analysis revealed pH variations ranging from - 0.1 to 1.0, with the most pronounced change observed in the white sand proppant (ΔpH = 1.0). The micro-CT analysis shows morphological and particle changes post reaction with resin-coated proppants exhibiting evidence of resin activation and redistribution, potentially influencing proppant pack conductivity. Post-reaction characterization via X-ray diffraction (XRD) identified the formation of new mineral phases in the ULD ceramic proppants, suggesting thermo-chemical interactions. While the ULD ceramic proppants demonstrated minimal physical degradation, sand-based proppants underwent notable morphological alterations based on pH changes and micro-CT analysis. These findings underscore the influence of proppant composition on fluid interactions in geothermal environments. However, to fully characterize proppant behavior and optimize material selection for Enhanced Geothermal Systems (EGS), further investigations at reservoir-representative temperatures exceeding 200°C are warranted.