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| Corrosion Behavior and Film Characteristics of S13Cr Stainless Steel under Ultra-High-Temperature Supercritical CO2 Environment |
| Received:September 29, 2020 Revised:November 25, 2020 |
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| DOI：10.7643/issn.1672-9242.2021.01.002 |
| KeyWord:S13Cr stainless steel supercritical CO2 H2S HTHP corrosion casing and tubing |
| Author | Institution |
| HE Song |
CNOOC Research Institute Co., Ltd., Beijing , China |
| WANG Bei |
University of Science & Technology Beijing, Beijing , China |
| FENG Huan-zhi |
CNOOC Research Institute Co., Ltd., Beijing , China |
| LU Min-xu |
University of Science & Technology Beijing, Beijing , China |
| ZHOU Ding-zhao |
CNOOC Research Institute Co., Ltd., Beijing , China |
| XING Xi-jin |
CNOOC Research Institute Co., Ltd., Beijing , China |
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| Abstract: |
| To clarify the applicability, corrosion resistance and correction film characteristics of S13Cr stainless steel under ultra-high-temperature supercritical CO2 environment, HTHP reactor was adopted to simulate the ultra-high-temperature supercritical CO2 environment at the bottom of gas well. The corrosion rate was measured by correction weight loss methods; the corrosion film characteristics were analyzed by the scanning electron microscope (SEM), energy spectrum (EDS), and X-ray diffraction (XRD). The results show that S13Cr steel presents uniform corrosion characteristics in the supercritical phase containing saturated water and condensate water phase containing saturated CO2, with corrosion rates of 0.009 mm/a and 0.126 mm/a respectively at 215 ℃, 31.2 MPa CO2 partial pressure, and 7.24 kPa H2S partial pressure. Both CO2 and H2S control corrosion. Corrosion film is a double-layer structure. The inner corrosion film is mainly FeCO3; the outer film is mainly pyrrhotite. The binding force between the inner and outer films is weak, so they are easy to flake off. The corrosion film in the supercritical phase is relatively sparse, while that in the water phase is much denser, but the outer film is prone to crack and flack off. Taking 0.125 mm/a as the casing and tubing material selection standard, S13Cr can be selected as casing and tubing material for gas wells with only condensate water and without water accumulation (temperature≤215 ℃, ≤31.2 MPa, ≤7.24 kPa, Cl–≤4646 mg/L). However, S13Cr is not suitable for such too severe working conditions if there is serious water accumulation at the bottom of the well or oil wells with high water content. |
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