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| Corrosion Behavior of Casing Steel with Different Materials in CO2 and H2S Environment |
| Received:April 20, 2020 Revised:May 10, 2020 |
| View Full Text View/Add Comment Download reader |
| DOI：10.7643/issn.1672-9242.2021.01.009 |
| KeyWord:CO2 H2S casing steel corrosion mechanism corrosion rate |
| Author | Institution |
| XIE Tao |
State Key Laboratory Offshore Oil Exploitation, Tianjin Branch of CNOOC China Limited, Tianjin , China |
| ZHANG Xiao-cheng |
State Key Laboratory Offshore Oil Exploitation, Tianjin Branch of CNOOC China Limited, Tianjin , China |
| LIN Hai |
State Key Laboratory Offshore Oil Exploitation, Tianjin Branch of CNOOC China Limited, Tianjin , China |
| DOU Peng |
State Key Laboratory Offshore Oil Exploitation, Tianjin Branch of CNOOC China Limited, Tianjin , China |
| SUN Lian-po |
State Key Laboratory Offshore Oil Exploitation, Tianjin Branch of CNOOC China Limited, Tianjin , China |
| YAN Wei |
China University of Petroleum, Beijing , China |
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| Abstract: |
| To study the corrosion characteristics of different casing materials in the coexistence environment of CO2 and H2S. The simulated experiment is carried out using high temperature and high pressure corrosion instrument and taking actual produced water samples from an oilfield of the Bohai sea as corrosion medium. The morphology and composition of corrosion products on the surface of corrosion specimens in different corrosion environment are analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDAX). The corrosion rates of different steels in the corrosive environment are measured, and a long-term corrosion rate prediction model is established. The results show that N80 has local corrosion in single CO2 environment (partial pressure is 0.1 MPa) when the temperature is 50 ℃, and the others present uniform corrosion. The difference of surface corrosion between carbon steel and low Cr steel is small in the coexistence environment of CO2 (partial pressure is 0.1MPa) and H2S (partial pressure is 0.0006 MPa), with both of them presenting uniform corrosion. Trace H2S has improved the corrosion environment, leading less surface corrosion to 13Cr steel, which is almost no corrosion; Compared with corrosion rate between environments of single CO2 and CO2 / H2S, the corrosion rate was reduced more than 60%. With the increase of testing time, the corrosion rate of several materials decreases in the form of power function. The long-term corrosion rates of N80, 1Cr and 3Cr materials are 0.023mm/a, 0.19 mm/a and 0.13mm/a respectively. Trace H2S has obvious inhibition effect on CO2 corrosion. 3Cr-N80 casing with over 69.983 kg/m can meet the requirements of casing strength after corrosion. |
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