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为了研究井下环境下常用油井管材间组合使用的电偶腐蚀特性,采用测量常用油井管材的开路电位、腐蚀电位及极化曲线获得电偶腐蚀规律,并在实际油田井下环境进行了实例研究,获得了常用井下防腐材料的曲线。分析表明:随着金属材质中铬含量的增加,其电位增加明显,金属材质的耐蚀性能增加;同一种金属材质,随管材钢级的增加其电位略有增加,耐蚀性能提高不明显。通过对常用材质的开路电位与腐蚀电位测试,对油田实例研究的方案进行简化,以中东某油田Asmari油层为实验井下腐蚀环境,研究了3Cr、9Cr、13Cr及Super13Cr之间的电偶腐蚀规律。实验测试结果表明,3Cr材质与超级13Cr混合连接后,接触位置的腐蚀加重程度增加近50%,若是采用9Cr材质过度,3Cr材质腐蚀加速程度大幅降低至15%,9Cr材质本身的腐蚀加重程度也低于15%。钢级对电偶腐蚀影响较小,采用中间材质过渡有利于保护低铬合金,提高其使用寿命。
In order to study the galvanic corrosion characteristics of the commonly used oil well pipe in underground environment, the galvanic corrosion was obtained by measuring the open circuit potential, corrosion potential and polarization curve of the commonly used oil well pipe. An example study was conducted on the actual oilfield downhole environment. Downhole corrosion of commonly used materials curve. The results show that with the increase of chromium content, the potential increases obviously and the corrosion resistance of metal material increases. With the same metal material, the potential increases slightly with the increase of steel grade, and the corrosion resistance is not obvious. By analyzing the open circuit potential and corrosion potential of commonly used materials, the scheme of oilfield case study is simplified. The corrosion of the Asmari reservoir in a certain oilfield in the Middle East is investigated. The galvanic corrosion between 3Cr, 9Cr, 13Cr and Super13Cr is studied. Experimental results show that, 3Cr material and super 13Cr hybrid connection, the contact position of the corrosion increased by nearly 50%, if the use of 9Cr material over, 3Cr material corrosion acceleration greatly reduced to 15%, 9Cr material itself, the degree of corrosion is also increased Below 15%. Steel grade galvanic corrosion less affected, the use of intermediate material transition is conducive to the protection of low-chromium alloy, improve its service life.