Cailiao Baohu (Jun 2024)

Study on Numerical Simulation of the Interference Protection of Cathodic Protection System for Double-Pipe Pipelines Laid in the Same Trench

  • CHEN Shuai, LI Hongfu, LUO Xiaowu, XIAO Huihui, SHI Yanjie, LUO Taixing, LIU Yanming, WANG Chen, LYU Xianghong, CUI Guanglei

DOI
https://doi.org/10.16577/j.issn.1001-1560.2024.0141
Journal volume & issue
Vol. 57, no. 6
pp. 175 – 185

Abstract

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In order to clarify the mutual interference law and interference protection measures of the cathodic protection system of double-pipe pipelines laid in the same trench, a double-pipe same trench laying pipelines(D219 and D457) in Xinjiang oilfield was taken as a model, the coating breakage rate of D219 pipeline was set to 0.1%, and the coating breakage rates of D457 pipelines were set to 0.1%, 0.5%, 1.0%. Numerical simulation methods were used to evaluate the effectiveness and applicability of different cathodic protection designs and cathodic protection interference protection measures. Results showed that mutual interference of cathodic protection systems existed in the pipeline laying in the same trench with shallow buried anode separate cathodic protection. The interference degree of parallel D219 pipelines was enhanced as the breakage rate of the D457 anti-corrosion layer of the interfering pipeline increased, and equalizing line measures could be applied to reduce the interference effectively. The joint cathodic protection measures with shallow buried anode and equalizing line could eliminate the mutual interference of cathodic protection systems for the same trench laying pipelines. The improvement of cathodic protection effect was more significant when the difference in the breakage rate of the anti-corrosion layer of the same trench double-pipe pipelines was large(0.1% of D219 and 1.0% of D457). For the same trench pipelines under joint cathodic protection measures with deep well anode, the cathodic protection effect was poor when the breakage rate of the D457 anti-corrosion layer was large(1.0%) and the soil resistivity was high(50 Ω·m). The improvement of cathodic protection effect was not significant by equalizing line and sacrificial anode measures. Increasing the output current of the deep well anode combined with equalizing line measures could significantly improve the cathodic protection effect of pipelines laid in the same trench.

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