Stress corrosion cracking and localized corrosion of downhole tubular steels in petroleum fluid containing CO2/Cl−

Purpose The purpose of this study is to investigate the susceptibility of L80, and other steels with 1% Cr, 3% Cr and 9% Cr, to stress corrosion cracking (SCC), pitting, crevice and stress concentration effect at the existing conditions of an oil reservoir. Design/methodology/approach The 4-points bent beam specimens were employed in the experimental works. The experimental works were performed at 82°C in a simulated environment that contains CO2 and Cl−. The effect of stress concentration on corrosion rate was confirmed by the novel circumferential notched tensile (CNT) specimen approach. Findings The results indicate that these steel grades are not susceptible to SCC in the given condition, and are promising materials for the application. The L80, 1% Cr and 3% Cr steels were attacked by pitting and crevice corrosion, while the 9% Cr steel was insignificantly affected, presumably due to its higher Cr, Mo and Ni contents. The local corrosion concentrated on sites that have high stress concentration. The CNT specimens confirmed the effect of stress concentration on promoting the local corrosion. Originality/value The study provides an essential insight into the susceptibility of downhole tubular to SCC for L80, 1% Cr, 3% Cr and 9% Cr steels in simulated reservoirs environment that contains CO2 and Cl−. A novel fracture mechanics approach using the CNT specimen method was introduced in investigating the effect of stress intensity on corrosion rate.