Flow Loop Study of Chloride Concentration Effect on Erosion, Corrosion and Erosion-Corrosion of carbon Steel in CO_2 Saturated Systems

摘要

Erosion-corrosion deterioration of carbon steel in CO_2-saturated systems with sand is a problemin the oil and gas industry because the combined effects of erosion and corrosion can reduce theprotection provided by iron-carbonate scale formation or inhibitors.Oil and gas production can be accompanied by the formation water (typically chloride containingbrine). Some effects of chloride concentration on corrosion are not widely known, and this can result inmisleading conclusions. The goal of this paper is to contribute to a better understanding of the effectsof chloride concentration in CO_2 corrosion. Previous studies reported in the literature and experimentaland theoretical studies conducted in the present work have shown that increasing the NaClconcentration in solution has three important effects on corrosion results. First, standard pH meterreadings in high NaCl concentration solutions require corrections. Second, increasing the NaClconcentration decreases the CO_2 concentration in solution and therefore contributes to a decrease inthe corrosion rate. Third, increasing the NaCl concentration increases the solubility of FeCO_3 andtherefore reduces the likelihood of forming an iron carbonate scale. High NaCl concentration alsodecreases the sand erosion rate of the metal slightly by increasing the density and viscosity of theliquid.