Experimental Research on Corrosion Resistant Rubber Based on Supercritical CO2 Injection Process

Abstract

In the CO2 injection process, the CO2 in the supercritical state and the H2S gas produced in the well have strong corrosion ability to the rubber material in the tool, therefore, it is necessary to study the rubber material suitable for the supercritical CO2 injection process. According to the H2S concentration in a CO2 injection block of Yushulin oil field in Daqing, Select six kinds of rubber materials for common underground tools to carry out CO2, H2S corrosion test, and heat resistance test. According to the experimental results, choose the rubber with the best performance. And then, characterize the molecular structure of the selected rubber samples to verify the corrosion resistance of CO2 and H2S. The results show that supercritical CO2 gas has strong solubility in perfluoroether rubber, type-A fluoroelastomer, and tetrapropyl fluoroelastomer; nitrile-butadiene rubber and ethylene-propylene-diene misch-polymere have poor heat-resistant-aging property; hydrogenated butadiene-acrylonitrile rubber and ethylene-propylene-diene misch-polymere have good resistance to high temperature; nitrile-butadiene rubber has the worst resistance to high temperature; hydrogenated butadiene-acrylonitrile rubber has high mechanical properties before and after aging and strong supercritical CO2 corrosion resistance. So, hydrogenated NBR is the best rubber material suitable for supercritical CO2 injection process. The changes in performance parameters of six common rubber materials before and after corrosion are obtained under high temperature and high pressure CO2 and H2S gas environment. It provides a reference for rubber materials of downhole tool selection in supercritical CO2 injection process.