Application Specific Rapid Gas Decompression Testing for Oilfield Elastomers Under Ultra-High H2S Environment

Abstract The oil and gas industry requires reliable and efficient sealing solutions to ensure the safe and effective operation of equipment in ultra-sour harsh conditions. Rapid Gas Decompression (RGD) testing is a crucial process for evaluating the performance of elastomer materials in harsh oilfield environments. However, standard testing methods may not accurately replicate the conditions encountered in real-world applications. Recent research has focused on developing a modified methodology of RGD testing that closely mimics the oilfield seal environment and harsh application conditions. The study involved testing five FKM materials and two FEPM materials in two bespoke ISO 23936-2 RGD tests. The tests utilized "Free Flow" gas fixtures to equalize pressure on both sides of each O-ring, ensuring a more realistic representation of oilfield conditions. The first test followed the standard procedure, except for the use of a gas mixture containing 40% H2S, 10% CO2, and 50% CH4. The second test increased the pressure to 5,000-psi and introduced a backup ring to limit movement and increase groove fill, bringing the test specimens closer to service conditions. The results of the testing revealed a significant change in the response of the materials when application configured geometry was considered, more accurately recreating the conditions that Ram Seals would see in service when installed in Blowout Preventers (BOPs). Several materials did not exhibit signs of crack growth or propagation when tested to application conditions. The most favorable results were found in the FKM materials, with an emphasis on low-temperature grade polymers returning the best possible results. One FEPM material showed some crack growth, but it did not propagate enough to cause failure. In contrast, the second FEPM material experienced extensive crack growth and propagation, resulting in failure. The study's findings emphasize the importance of testing materials in realistic conditions to ensure the safe and efficient operation of oilfield equipment. By adopting this new testing protocol, the oil and gas industry can make more informed decisions when selecting materials for critical applications, ultimately leading to improved safety, efficiency, and reliability. The unique work performed in this comparative study highlighted that testing to application and replicating seal conditions provides more meaningful results in oilfield applications. Strict adherence to a testing standard allows for material comparisons but cannot capture the nuances of the field unless heavily modified. The superiority of FKM polymers over FEPM polymers in these tests cannot be understated. The natural advantages of FKM polymers can increase longevity of seals allowing for efficiency improvements.