Evaluation of the Performance of O-rings Made With Different Elastomeric Polymers In Simulated Geothermal Environments at 300°C.

摘要

This paper aims to evaluate the survival of O-rings made with six different elastomeric polymers, EPDM, type I- and II-FKM, FEPM, FFKM, and FSR, in five different simulated geothermal environments at 300°C. It further defines the relative strengths and weaknesses of the materials in each environment. The environments tested were: 1) non-aerated steam-cooling cycles, 2) aerated steam-cooling cycles, 3) water-based drilling fluid, 4) CO2-rich geo-brine fluid, and, 5) heat-cool water quenching cycles. Following exposure, the extent of oxidation, oxidation-induced degradation, thermal behaviors, micro-defects, permeation depths of ionic species present in environments throughout the O-ring, silicate-related scale-deposition, and changes in mechanical properties were assessed. The reliability of the O-ring maintaining its integrity depended on the exposure environment. For instance, EPDM was oxidized to some degree in all environments, leading to the incorporation of oxidation derivatives into its molecular structure. The highest degree of oxidation was observed from a heat-water quenching environment which was designed to simulate thermal shock, causing the greatest decline in the integrity of the O-ring. Moderate oxidation, which occurred in all other environments, did not significantly change the integrity of O-rings, except for depositing silicate scales on their surfaces. Correspondingly, there was no creation of any micro-defects in the O-rings during exposure, nor did ionic species permeate through the oxidized O-rings