Effect of Temperature on Corrosion Behavior of S135 Steel and G105 Steel in CO₂/H₂S Coexisting System

The corrosion tests of S135 steel and G105 steel were carried out by high temperature autoclaves at different temperatures (room temperature, 100 ℃, 180 ℃) in the simulated oil field formation water coexisted CO₂/H₂S gas with partial pressure of 20, 0.1 MPa, respectively. The influence of temperature on the corrosion behavior of the two steels was studied. The results show that the corrosion rate of S135 steel and G105 steel was the biggest at 100 ℃, reaching 0.846 3, 0.850 0 mm·a^-1, respectively, while that at 180 ℃ was the smallest of 0.229 1, 0.230 9 mm·a^-1, respectively. At 100 ℃, the corrosion products on the steel surface were mainly FeCO₃ and FeS, and CO₂ was the main controlling factor for corrosion. At the room temperature and 180 ℃, the corrosion products were mainly FeS, and H₂S was the main controlling factor for corrosion.