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| Applicability Evaluation of String Corrosion in High Temperature and High Pressure Gas Wells Containing CO2 in South China Sea |
| Received:September 05, 2020 Revised:October 19, 2020 |
| View Full Text View/Add Comment Download reader |
| DOI：10.7643/issn.1672-9242.2021.01.003 |
| KeyWord:CO2 corrosion high temperature and high pressure South China Sea gas well containing CO2 Cr steel |
| Author | Institution |
| LI Yan-jun |
CNOOC China Co, Ltd.Zhanjiang Branch, Zhanjiang , China |
| ZHANG Chao |
CNOOC China Co, Ltd.Zhanjiang Branch, Zhanjiang , China |
| DING Jian |
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu , China |
| WU Jiang |
CNOOC China Co, Ltd.Zhanjiang Branch, Zhanjiang , China |
| ZHANG Wan-dong |
CNOOC China Co, Ltd.Zhanjiang Branch, Zhanjiang , China |
| ZHANG Zhi |
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu , China |
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| Abstract: |
| This paper aims to clarify the corrosion applicability of string materials for high-temperature and high-pressure gas wells in South China Sea and guide the selection of field string materials. The corrosion rate of different materials in wellbore under high temperature and high pressure environment is analyzed by using high temperature and high pressure kettle corrosion test instrument, and the corrosion morphology of samples after corrosion test is analyzed by using scanning electron microscope and energy spectrum analyzer to evaluate the corrosion applicability of pipe string materials in different wellbore environments. The results show that:at 150 ℃, the corrosion rate increases with the increase of partial pressure, and decreases with the increase of Cr content. The corrosion rate of P110 steel reaches 0.3511 mm/a, which belongs to serious corrosion; at 180℃, there are different degrees of local corrosion on the surface of three kinds of materials, and the pitting corrosion degree of 13CrS -110 sample is higher than that of other materials. The pitting pits tend to extend inward. Therefore, in the high temperature and high pressure CO2 environment in the South China Sea, the increase of Cr content improves the corrosion resistance of the materials, and with the increase of the partial pressure of CO2, the solubility of CO2 in the solution increases, which increases the material corrosion; under the high temperature of 180℃, the pitting corrosion exists in 13CrS-110 steel, 15Cr-110 steel and 15Cr-125 steel, but 13CrS-110 steel has the risk of cracking. Cracking risk assessment should be carried out before field application. In view of the string material selection for high temperature and high pressure gas well containing CO2, according to the wellbore temperature, pressure and CO2 partial pressure distribution, the design can be carried out in sections so that the development cost can be reduced on the basis of ensuring the integrity of the wellbore. |
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