Study on CO₂ and H₂S Corrosion of J55 and 3Cr in Simulated Changqing Oilfield Environment

Abstract

Studying casing corrosion mechanism and seeking alternative corrosion-resistant materials are the fundamental ways to slove the increasingly serious problem of casing corrosion in oilfields. Herein， by simulating the field corrosion conditions of Changqing Oilfield， the corrosion behavior of J55 and 3Cr materials in the environment of a CO2 partial pressure of 1.0 MPa， a H2S partial pressure of 0.3 MPa and a temperature of 60 ℃was studied. Additionally， the morphology and components of the corrosion products of these two materials were analyzed by means of scanning electron microscopy， energy spectroscopy and X-ray diffraction. Results showed that the enrichment of Cr element in the corrosion product film and the formation of Cr(OH)3 improved the stability and compactness of the corrosion products， making 3Cr exhibit better corrosion resistance than J55. In the environment containing both CO2 and H2S， H2S corrosion played a dominant role. The loose corrosion product film formed in CO2 corrosion made the uniform corrosion rates of J55 and 3Cr higher than those in environments containing H2S alone and containing both H2S and CO2.

Keywords

• j55 steel|3cr steel|co2 corrosion|h2s corrosion