Flow Loop Study of Chloride Concentration Effect on Erosion, Corrosion and Erosion-Corrosion of Carbon Steel in CO2 Saturated Systems

Large volumes of brine usually accompany oil and gas production.  The goal of this paper is to contribute to a better understanding of the effects of chloride concentration in CO₂ corrosion and erosion-corrosion.  Experimental and theoretical studies conducted in the present work confirm some of the previous studies found in the literature that have shown that increasing the NaCl concentration in solution has three important effects on corrosion and interpreting corrosion research results. First, standard pH meter readings in high NaCl concentration solutions require corrections. Second, increasing the NaCl concentration decreases the CO₂ concentration in solution and therefore contributes to a decrease in the corrosion rate. Third, increasing the NaCl concentration increases the solubility product of FeCO₃, K_sp. A high NaCl concentration also decreases the sand erosion rate of the metal slightly by increasing the density and viscosity of the liquid.

The Linear Polarization Resistance (LPR) and long-term weight loss measurement techniques were used to evaluate the effects of NaCl concentration on erosion, corrosion and erosion-corrosion behavior of 1018 carbon steel in flow loop testing under single phase flow and CO₂ pressure conditions. Results are presented and discussed in terms of expectations based on information available in the corrosion literature on effects of NaCl concentration.