Technical Notebook: Solubility and diffusivity of CO2 in fluoroelastomers and their impact on elastomer sealing in API high-pressure testing

Solubility and diffusivity of CO2 in elastomers are important properties for not only oil and gas applications, but also carbon capture and sequestration (CCS). Because CO2 is the most important greenhouse gas, the capture, transportation and sequestration of CO2 have a great impact on global warming. Investigation into CO2 solubility and diffusivity in elastomers and plastics at high pressure and various temperatures is crucial for developing non-metal materials for CCS technology.

In this paper, the solubility and diffusivity of CO2 in elastomers at extreme high pressure (more than 100 MPa) and elevated temperatures were estimated based on experimental data and theoretical calculations. These results were applied to the fixture test in API-SPEC 6A to calculate the pressure reduction during the pressure holding of an FKM seal under a pressure of more than 100 MPa.

The effects of CO2 solubility, diffusivity and other test conditions on an elastomer seal were investigated. Understanding the solubility and diffusivity of CO2 in elastomers under extreme high pressure (more than 100 MPa) and elevated temperatures (more than 100ºC) is critical for developing new elastomer seals suitable for high-pressure/high-temperature applications.