Experimental Evaluation of Anticorrosion of a Standard 20# Gathering Pipeline by Injecting Oxygen-Reduced Air into Simulated In-Service Wells

Abstract

Oxygen-reduced air flooding (ORAF) can effectively improve oil recovery in low-permeability reservoirs, but oxygen corrosion and CO₂ corrosion in downstream gathering pipelines are inevitable due to the existence of oxygen, which limits the popularization and application of ORAF. In this paper, research on the corrosion inhibitor is carried out for the gathering pipeline of an oilfield with ORAF in China. Under the conditions of a simulated onsite gathering pipeline, 6 kinds of anti-CO₂ corrosion inhibitors and 6 kinds of antioxygen corrosion inhibitors were selected to evaluate and screen the effects of 20# steel by the dynamic weight loss method. Two antioxygen corrosion inhibitors KY-12 and KY-17 and one anti-CO₂ corrosion inhibitor A were selected for the experiment. The corrosion inhibition rates of the three inhibitors reached 83.67, 91.49, and 78.44%, respectively, at a temperature of 40 °C and an inhibitor concentration of 1000 mg/L. Through the experimental evaluation of three primary corrosion inhibitors at different temperatures (25, 40, and 55 °C) and different concentrations (400, 500, 800, 1000, and 2000 mg/L), the KY-17 corrosion inhibitor with the best stability at different temperatures was selected, and the corrosion inhibition effect was the best at different concentrations, with the highest slow release rate reaching 92.7%. This conclusion has a good reference significance for the selection and dosage of corrosion inhibitors for downstream gathering pipelines of the ORAF oilfield.