Multiscale Characterization of Thermo-Hydro-Chemical Interactions Between Proppants and Fluids in Low-Temperature EGS Conditions
Enhanced Geothermal Systems (EGS) require thermochemically stable proppant materials capable of sustaining fracture conductivity under harsh subsurface conditions. This study systematically investigates the response of commercial proppants to coupled thermo-hydro-chemical (THC) effects, focusing on...
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2025-07-01
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| author | Bruce Mutume Ali Ettehadi B. Dulani Dhanapala Terry Palisch Mileva Radonjic |
| author_facet | Bruce Mutume Ali Ettehadi B. Dulani Dhanapala Terry Palisch Mileva Radonjic |
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| description | Enhanced Geothermal Systems (EGS) require thermochemically stable proppant materials capable of sustaining fracture conductivity under harsh subsurface conditions. This study systematically investigates the response of commercial proppants to coupled thermo-hydro-chemical (THC) effects, focusing on chemical stability and microstructural evolution. Four proppant types were evaluated: an ultra-low-density ceramic (ULD), a resin-coated sand (RCS), and two quartz-based silica sands. Experiments were conducted under simulated EGS conditions at 130 °C with daily thermal cycling over a 25-day period, using diluted site-specific Utah FORGE geothermal fluids. Static batch reactions were followed by comprehensive multi-modal characterization, including scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), and micro-computed tomography (micro-CT). Proppants were tested in both granular and powdered forms to evaluate surface area effects and potential long-term reactivity. Results indicate that ULD proppants experienced notable resin degradation and secondary mineral precipitation within internal pore networks, evidenced by a 30.4% reduction in intragranular porosity (from CT analysis) and diminished amorphous peaks in the XRD spectra. RCS proppants exhibited a significant loss of surface carbon content from 72.98% to 53.05%, consistent with resin breakdown observed via SEM imaging. While the quartz-based sand proppants remained morphologically intact at the macro-scale, SEM-EDS revealed localized surface alteration and mineral precipitation. The brown sand proppant, in particular, showed the most extensive surface precipitation, with a 15.2% increase in newly detected mineral phases. These findings advance understanding of proppant–fluid interactions under low-temperature EGS conditions and underscore the importance of selecting proppants based on thermo-chemical compatibility. The results also highlight the need for continued development of chemically resilient proppant formulations tailored for long-term geothermal applications. |
| format | Article |
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| institution | Kabale University |
| issn | 1996-1073 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | MDPI AG |
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| series | Energies |
| spelling | doaj-art-0eb6cfbe7bb94066b8d77b3ed830916b2025-08-20T04:00:49ZengMDPI AGEnergies1996-10732025-07-011815397410.3390/en18153974Multiscale Characterization of Thermo-Hydro-Chemical Interactions Between Proppants and Fluids in Low-Temperature EGS ConditionsBruce Mutume0Ali Ettehadi1B. Dulani Dhanapala2Terry Palisch3Mileva Radonjic4Hydraulic Barrier Material and Geomimicry Laboratory, School of Chemical Engineering, Oklahoma State University, 420 Engineering North, Stillwater, OK 74078, USAHydraulic Barrier Material and Geomimicry Laboratory, School of Chemical Engineering, Oklahoma State University, 420 Engineering North, Stillwater, OK 74078, USAATRC Imaging Suite, College of Engineering, Architecture, and Technology, Oklahoma State University, 420 Engineering North, Stillwater, OK 74078, USACARBO Ceramics Inc., 5050 Westway Park Blvd, Houston, TX 77041, USAHydraulic Barrier Material and Geomimicry Laboratory, School of Chemical Engineering, Oklahoma State University, 420 Engineering North, Stillwater, OK 74078, USAEnhanced Geothermal Systems (EGS) require thermochemically stable proppant materials capable of sustaining fracture conductivity under harsh subsurface conditions. This study systematically investigates the response of commercial proppants to coupled thermo-hydro-chemical (THC) effects, focusing on chemical stability and microstructural evolution. Four proppant types were evaluated: an ultra-low-density ceramic (ULD), a resin-coated sand (RCS), and two quartz-based silica sands. Experiments were conducted under simulated EGS conditions at 130 °C with daily thermal cycling over a 25-day period, using diluted site-specific Utah FORGE geothermal fluids. Static batch reactions were followed by comprehensive multi-modal characterization, including scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), and micro-computed tomography (micro-CT). Proppants were tested in both granular and powdered forms to evaluate surface area effects and potential long-term reactivity. Results indicate that ULD proppants experienced notable resin degradation and secondary mineral precipitation within internal pore networks, evidenced by a 30.4% reduction in intragranular porosity (from CT analysis) and diminished amorphous peaks in the XRD spectra. RCS proppants exhibited a significant loss of surface carbon content from 72.98% to 53.05%, consistent with resin breakdown observed via SEM imaging. While the quartz-based sand proppants remained morphologically intact at the macro-scale, SEM-EDS revealed localized surface alteration and mineral precipitation. The brown sand proppant, in particular, showed the most extensive surface precipitation, with a 15.2% increase in newly detected mineral phases. These findings advance understanding of proppant–fluid interactions under low-temperature EGS conditions and underscore the importance of selecting proppants based on thermo-chemical compatibility. The results also highlight the need for continued development of chemically resilient proppant formulations tailored for long-term geothermal applications.https://www.mdpi.com/1996-1073/18/15/3974proppant stabilityenhanced geothermal systemsEGS hydraulic fracturingthermal cyclingUtah FORGEfluid-solid interactions |
| spellingShingle | Bruce Mutume Ali Ettehadi B. Dulani Dhanapala Terry Palisch Mileva Radonjic Multiscale Characterization of Thermo-Hydro-Chemical Interactions Between Proppants and Fluids in Low-Temperature EGS Conditions Energies proppant stability enhanced geothermal systems EGS hydraulic fracturing thermal cycling Utah FORGE fluid-solid interactions |
| title | Multiscale Characterization of Thermo-Hydro-Chemical Interactions Between Proppants and Fluids in Low-Temperature EGS Conditions |
| title_full | Multiscale Characterization of Thermo-Hydro-Chemical Interactions Between Proppants and Fluids in Low-Temperature EGS Conditions |
| title_fullStr | Multiscale Characterization of Thermo-Hydro-Chemical Interactions Between Proppants and Fluids in Low-Temperature EGS Conditions |
| title_full_unstemmed | Multiscale Characterization of Thermo-Hydro-Chemical Interactions Between Proppants and Fluids in Low-Temperature EGS Conditions |
| title_short | Multiscale Characterization of Thermo-Hydro-Chemical Interactions Between Proppants and Fluids in Low-Temperature EGS Conditions |
| title_sort | multiscale characterization of thermo hydro chemical interactions between proppants and fluids in low temperature egs conditions |
| topic | proppant stability enhanced geothermal systems EGS hydraulic fracturing thermal cycling Utah FORGE fluid-solid interactions |
| url | https://www.mdpi.com/1996-1073/18/15/3974 |
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