Corrosion of carbon steel in CO2 saturated brine at elevated temperatures

One of the main challenges in oil and gas wells is ensuring wellbore and casing integrity in a CO2 saturated brine environment. The integrity of a well casing relies on its mechanical properties and corrosion resistance to harsh downhole conditions. This paper discloses the results of a mathematical modeling study and experimental investigation conducted to understand the corrosion behavior of carbon steel (AISI 1045 Medium Carbon steel) in CO2 saturated brine. Corrosion experiments were carried out at 0.83 MPa varying temperature and CO2 partial pressure (CPP). To prepare test fluid, 1 wt % NaCl was added to deionized water and thoroughly mixed. The Weight loss (WL) and Linear polarization resistance (LPR) techniques were employed for investigating corrosion. A comprehensive corrosion model is formulated to predict corrosion in a CO2 environment containing high-salt concentration. Results indicate a strong impact of temperature on CO2 corrosion in brine environment. At low CPPs (P-CO2 <= 0.41 MPa), the pick corrosion rate was noted at 43 degrees C. Furthermore, the influence of NaCl content on corrosion was strongly affected by CO2 concentration. The model is predominantly in agreement with existing corrosion measurements and it predicts the inhibiting effect of salt in CO2 corrosion.