CO_2 Corrosion Behaviors of Tubing and Casing Steels in Simulation Produced Water for Deep Natural Gas Wells

摘要

The influence of temperature and CO_2 partial pressure on tubing and casing steels widely used in Daqing Oilfield including J55, N80 and P110 steels in simulation water for deep natural gas wells with CO_2 corrosion was studied, using autoclave, Scanning Electron Microscope (SEM), Energy Spectrum Analysis (ESA), X-Ray Diffraction (XRD). The results show that the average corrosion rate of the test steel increases rapidly at first as temperature rises until 60°C, then decreases rapidly as temperature continues to rise; the average corrosion rate increases rapidly as CO_2 partial pressure rises until a peak is reached, then tends to be flat as temperature continues to rise; CO_2 corrosion products are mainly FeCO_3 and CaMg(CO_3)_2.