Field Corrosion Rates of Oilfield Carbon and Low-Alloy Steels across the Sweet-to-Sour (CO 2 /H 2 S) Spectrum: A Field Dataset and a Benchmark of Predictive Models

Abstract

Internal corrosion of carbon and low-alloy steels by dissolved carbon dioxide (CO 2 ) and hydrogen sulfide (H 2 S) is a leading integrity threat in oil and gas production and transportation, yet field corrosion rates are rarely reported together with the quantified partial pressures that control them, which limits validation of engineering prediction models across the full sweet-to-sour range. This work compiles 90 field corrosion-rate measurements from operating oil and gas assets of an anonymous client operator, each paired with the steel grade, the operating temperature and pressure, the gas-phase CO 2 and H 2 S contents, water chemistry, flow velocity and inhibitor status. Carbon dioxide and hydrogen sulfide partial pressures and in-situ pH were computed for every record, and each record was classified as sweet, mixed or sour from the pCO 2 /pH 2 S ratio. Measured rates ranged from 0.12 to 14.97 mm/yr (mean 2.29 mm/yr) and increased significantly with H 2 S partial pressure (r = +0.42, p in-situ pH (r = −0.49, p 2 S partial pressure. The results provide an anonymized, openly described field dataset and quantify the limits of CO 2 -only models in mixed and sour service.