Non-metallic Materials Suitability in Supercritical CO2 and H2S (C2026-00133)

Alireza Zolfaghari, Jushik Yun, Manuel Marya

As the energy industry increasingly expands its reliance on complex subsurface operations including oil and gas extraction, carbon storage, and geothermal development, the selection of elastomeric seals for downhole tools becomes increasingly challenging. These applications often involve harsh environments containing dense phases of CO₂ and H₂S, where conventional sealing materials may not maintain long term integrity. Fluoropolymers, particularly fluoroelastomers (FKMs) and perfluoroelastomers (FFKMs), are widely considered promising candidates owing to their chemical and thermal stability. This study evaluates the performances of oil and gas qualified FKMs and FFKMs exposed to dense phases of H₂S and CO₂ environments for 35 days. This process included five cycles of exposure to temperatures between 232°C and 25°C, partial pressures of H₂S and CO₂ each ranging from 6.9 to 1.6 MPa, and total pressures between 27.6 and 5.5 MPa. The test was performed in presence of water containing 180,000 ppm chloride and 1 g of sulfur.
Post characterization included mechanical testing, Infrared spectroscopy, thermal analysis, surface morphology analysis and elemental analysis to assess degradation mechanisms. Two FFKM compounds met ISO 23936-2 acceptance criteria. Results indicate that FFKMs can offer reliable performance with proper elastomer formulations and sealing design in extreme, sour and CO2 rich environments.