Investigation of pH₂S influence on 3% Cr tubing steel corrosion behaviours in CO₂–H₂S–Cl⁻environment

Abstract

A series of experiments were conducted in autoclave to investigate corrosion properties of low Cr oil country tubular goods in CO 2 /H 2 S saturated brine solution (3 wt-%NaCl) at 90uC. Test material is 3Cr-80, which is gradually accepted in oil and gas industry, especially for downhole tubing and casing. The CO 2 partial pressure was fixed at 4?0 bar in all experiments, and the H 2 S partial pressure was varied from 0, 2, 4, 8, 20, 40 and 800 mbar to 4000 mbar (4 bar). The results show that when the pH 2 S varied at a lower range (2-40 mbar), 3Cr-80 materials' corrosion rates were restricted, and coupons' surface morphologies became glossy compared to the pure CO 2 corrosion. Under the condition of pH 2 S5800 mbar, H 2 S no longer have a retardation effect on CO 2 corrosion but acceleration. The average corrosion rate was higher than pure CO 2 corrosion. When the pH 2 S rise to 4000 mbar (equal to the CO 2 partial pressure), 3Cr corroded much more severe and serious mesa attack was observed.

Role of polyacrylamide concentration on corrosion behavior of N80 steel in the HPAM/H2S/CO2 environment

“…Once the concentrations of [Fe 2+ ] × [S 2− ] and [Fe 2+ ] × [CO 3 2− ] exceed the solubility of FeS and FeCO 3 , FeS and FeCO 3 crystals will deposit on the metal surface (Equations and ) . As H 2 S/CO 2 acid gas is introduced into the autoclave, the solution in the autoclave is acidic . FeCO 3 crystals are prone to decompose in the acidic environment, while FeS is stable in this environment.…”

“…[22] As H 2 S/CO 2 acid gas is introduced into the autoclave, the solution in the autoclave is acidic. [23,24] FeCO 3 crystals are prone to decompose in the acidic environment, while FeS is stable in this environment. Besides this, the solubility product K spFes of FeS is lower than that of K spFeCO3 (25°C, K spFes = 6.3 × 10 −18 , K spFeCO3 = 3.2 × 10 −11 ), and more FeS are deposited on the metal surface.…”

The high-temperature mechanical properties of HS110S steel and its corrosion behaviors in harsh downhole environment

“…According to the survey, scholars across the world have made great achievement in the corrosion of CO 2 and H 2 S. It was found that the CO 2 /H 2 S corrosion was mainly affected by gas partial pressure, temperature, pH, fluid flow rates, medium, material and other factors (Yan et al , 2015; Zhang et al , 2015). However, the application research of sulfur-resistant steel at 350°C has not been found.…”

Effect of thiosulphate/H2S on crevice corrosion behaviour of P110 carbon steel in CO2-saturated solution

“…However, a small amount of H 2 S may be produced by sulfate-reducing bacteria [13]. The brine solution, containing CO 2 and H 2 S, is a corrosive medium, which accelerated localised corrosion such as pitting corrosion and sulphide stress corrosion cracking [12][13][14][15][16][17][18][19][20][21]. To date, a couple of studies have been conducted with a focus on the role of trace H 2 S in corrosion of carbon steel in the CO 2 -saturated solution [20][21][22][23][24][25][26][27][28][29].…”