International Journal of Hydrogen Energy | 2021
On how CO2 partial pressure on corrosion of HNBR rubber O-ring in CO2–H2S–CH4 environment
Abstract
Abstract Effect of CO2 partial pressure on corrosion of HNBR and FKM rubber O-rings was studied by using a HTHP autoclave and a self-designed O-ring pressure bearing device to simulate the service environment of the packer in the process of associated gas reinjection. Their mechanical properties, EDS and fracture morphology were analyzed. The results showed that as the CO2 partial pressure increased, the tensile strength, elongation and hardness of the two types of O-rings all decreased. Moreover, the fracture of both O-rings changed from ductile fracture to brittle fracture. In the free-state, the corrosion of the two O-rings in the liquid phase was more serious than in the gas phase. On the contrary, in the compressed state their corrosion in the gas phase was more serious than in the liquid phase. On the whole, the corrosion of the two O-rings in the free-state was more serious than in the compressed state. Their corrosion in CO2–H2S environment was influenced by the swelling and chemical reactions of medium molecules. The two O-rings in the compressed state reduced the contact area between O-ring and corrosive medium, resulting in slight corrosion of O-rings under compression. Due to its poor corrosion resistance and the sealing performance, HNBR O-ring had certain risk in the process of associated gas reinjection. FKM O-ring has good corrosion resistance and sealing performance in the CO2–H2S environment, so it can be well applied in this environment.