LU Yuan,ZHAO Jing-mao,ZHANG Mao,CHEN Sheng-li,HU Ting,ZHANG Yong.Development of CO2/H2S Corrosion Inhibitors in the Mixed Water Injection System of Offshore Oilfield in the Bohai Sea[J],47(10):59-65
Development of CO2/H2S Corrosion Inhibitors in the Mixed Water Injection System of Offshore Oilfield in the Bohai Sea
Received:January 07, 2018  Revised:October 20, 2018
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DOI:10.16490/j.cnki.issn.1001-3660.2018.10.008
KeyWord:mixed water injection  CO2/H2S corrosion  general corrosion  local corrosion  corrosion Inhibitor  anode type
                 
AuthorInstitution
LU Yuan 1. School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing , China; 2. CNOOC Ener Tech-Drilling & Production Co., Tianjin , China
ZHAO Jing-mao 1. School of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing , China
ZHANG Mao 2. CNOOC Ener Tech-Drilling & Production Co., Tianjin , China
CHEN Sheng-li 3. CNOOC Energy Technology & Services Limited, Beijing Branch, Beijing , China
HU Ting 2. CNOOC Ener Tech-Drilling & Production Co., Tianjin , China
ZHANG Yong 2. CNOOC Ener Tech-Drilling & Production Co., Tianjin , China
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Abstract:
      The work aims to reduce the serious CO2/H2S corrosion problems of water injection on offshore oilfield in the Bohai sea and the serious pittig corrosion of the test coupons. An imidazoline quaternary ammonium salt LH-31 applicable to the oilfiled conditions was synthesized and the optimum corrosion inhibitor was obtained through molecule compound. At 95 ℃ and 0.15 MPa CO2 (including 100 μg/g H2S), the blank average corrosion measured at total pressure of 0.5 MPa N2 and flow velocity of 1.5 m/s for 72 hours was 2.0101 mm/a and pitting corrosion rate was 1.1106 mm/a. The average corrosion decreased to 0.1000 mm/a and pitting corrosion rate reduced to 0.5789 mm/a after 40 mg/L LH-31 was added. LH-31 had an absorption peak in 879.31 cm-1. A stretching vibration might occur between the nitrogen atoms and adjacent carbons and the quaternary ammonium salts might be formed. LH-31 had synergistic effect with thiourea and sodium benzoate. The efficient compound corrosion inhibitor 2E composed of 4% thiourea and 3% sodium benzoate could reduce the average corrosion to 0.0200 mm/a and the pitting corrosion rate to 0.0751 mm/a. The polarization curve test showed that the corrosion inhibitor 2E was the anode type of corrosion inhibitor. After the corrosion inhibitor passed the bypass corrosion test for 1 day, the average depth of the test coupon was reduced to 0.0258 μm from 0.139 μm after adding 40 mg/L of 2E. The corrosion inhibitor can effectively inhibit the uniform corrosion and pitting corrosion of mixed water injection in the Bohai Sea.
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