Corrosion Law and Corrosion Prediction of Sucker Rod in CO₂ Composite Steam Flooding Production Well

Aiming at the corrosion problem of sucker rod in CO₂ composite steam flooding production well, simulated corrosion tests were carried out in a high temperature and high pressure autoclave to study the effects of temperature (60-120 ℃), partial pressure of CO₂ (0.1-0.3 MPa) and chloride ion concentration (1-3 g/L) on the corrosion of the sucker rod. A mathematical model for predicting the corrosion rate of sucker rods was established, and a corrosion rate prediction chart with comprehensive consideration of multiple factors was drawn. The results show that the corrosion rate of sucker rod increased first and then decreased with the increase of temperature, and reached the maximum value of 0.939 1 mm/a at 90 ℃. With the increase of partial pressure of CO₂ and chloride ion concentration, the corrosion rate of sucker rod gradually increased, and the main controlling factor of corrosion was partial pressure of CO₂. The predicted results from the corrosion prediction plate were in good agreement with the experimental results, so the corrosion prediction plate had good prediction accuracy and practicability.