Corrosion Performance of L80-1Cr and L80-3Cr Oil Country Tubular Goods (OCTG) in High CO_2 at Elevated Temperature

摘要

Sweet corrosion of Oil Country Tubular Goods (OCTG) is a major concern in the oil and gas industry. The severity of corrosion depends on temperature, CO_2 partial pressure, and material characteristics. In this paper, the effects of temperature and chromium content in OCTG steel on CO_2 corrosion are discussed. In addition, the effect of the design of laboratory corrosion testing apparatus on observed corrosion behavior is investigated. The L80 OCTG steel used in this study had Cr content in the range of 1 to 3 wt%. Two different designs of autoclaves, namely, rotating cage autoclave and autoclave with Rushton blade impeller were used for corrosion testing. In these experiments, weight loss corrosion rates were measured. Corrosion product scales were characterized using Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). Localized/pitting corrosion was also evaluated by scanning the corroded coupon surfaces (after scale removal) using an optical profilometer to obtain a detailed 3D surface profile image. This paper will present the experimental results and discuss the effects of temperature and Cr content in OCTG on corrosion rate.