CHEN Yi,XU Jie,JIA Li-xin,WANG Kong-yang,LIN Hai,YAN Wei.Casing Selection for Thermal Wells under Condition of Thermal Strength Attenuation and High Temperature Corrosion in Offshore Oilfield[J],47(2):195-201
Casing Selection for Thermal Wells under Condition of Thermal Strength Attenuation and High Temperature Corrosion in Offshore Oilfield
Received:July 28, 2017  Revised:February 20, 2018
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DOI:10.16490/j.cnki.issn.1001-3660.2018.02.031
KeyWord:heavy oil  steam stimulation  strength attenuation  CO2/H2S corrosion  casing selection
                 
AuthorInstitution
CHEN Yi CNOOC China Limited, Tianjin Branch, Tianjin , China
XU Jie CNOOC China Limited, Tianjin Branch, Tianjin , China
JIA Li-xin CNOOC China Limited, Tianjin Branch, Tianjin , China
WANG Kong-yang China University of Petroleum Beijing, Beijing , China
LIN Hai CNOOC China Limited, Tianjin Branch, Tianjin , China
YAN Wei China University of Petroleum Beijing, Beijing , China
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Abstract:
      The work aims to investigate applicability of different types of casings at high temperature and corrosive environment. With rock core and formation water of LD oilfield as corrosive medium, different types of casings were simulated and evaluated with a HTHP autoclave. Corrosion environment of the oilfield was determined by adopting gas chromatographic technique: MPa and MPa. Corrosion simulation experiments were conducted based on the maximum corrosion gas partial pressure, and corrosion rate of different steels in this corrosion environment was measured, then a prediction mode of long-term corrosion rate was built, long-term corrosion rate of 100H, 80-1Cr and 110-3Cr was 0.24 mm/a, 0.20 mm/a and 0.05 mm/a, respectively. According to the corrosion experiment results and strength attenuation law of heavy oil thermal well casing, strength design of thermal well casing was carried out, and safe life of 80-1Cr, 100H, 110-3Cr was 3.8 years, 6.5 years and 11.2 years, respectively. High temperature will reduce casing strength, and corrosion will change diameter-thickness ratio. Furthermore, cyclic steam injection will accelerate corrosion process, thus cut down service life of the casing. The study results are of guiding significance to material selection of thermal well casing in corrosion environment.
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