Effect of CO₂ content on corrosion non-uniformity of 20# steel in oil–water two-phase based on wire beam electrode technique

Abstract

With the widespread application of CO 2 -Enhanced Oilfield Recovery (CO 2 -EOR) technology, CO 2 in large quantities enters oil and gas gathering pipelines and causes severe corrosion. As a result, this paper investigates the corrosion behaviour of 20# steel in produced water and 40% water content emulsion with different CO 2 contents by combining Wire Beam Electrode (WBE) technology and the corrosion weight loss method, and establishes a corrosion mechanism model for analysis and explanation. The results demonstrate that variations in CO 2 concentration have a greater impact on the corrosion process in the produced water simulated fluid, and there is considerable corrosion non-uniformity in the CO 2 saturated state, as well as polarity reversal throughout the whole corrosion process. On the contrary, corrosion in the emulsion is more stable and uniform because the crude oil in the emulsion obstructs the mass transfer process of the depolariser agent and forms a 'surface wetting' effect on the metal surface, which seriously hinders the corrosion process.