套管对输油管道阴极保护电位影响数值模拟研究

Numerical simulation study for effect of casing on cathode protection potential of oil pipeline

通过数值模拟、实验模拟及现场勘测,研究了套管对输油管道阴极保护电位的影响。结果表明,第一,套管屏蔽管道表面阴极保护电流,减弱阴极保护作用;第二,套管两端未密封时阴极保护电流可以进入套管内的管道处,阴极保护起到一定作用,但此时外界环境中的水、土壤等杂质会进入套管和管道的环形空间,导致管道更容易发生腐蚀;第三,环形空间内电解质电导率越大,有套管处管道阴极保护电位越负;第四,在浅埋区时,随着埋设深度增加,有套管处管道阴极保护电位逐渐正移,而在深埋区时有套管处管道阴极保护作用几乎不受影响;第五,随着辅助阳极垂直距离的增大,套管处管道阴极保护电位逐渐正移,而远离有套管处管道的阴极保护电位负向移动;第六,随着阳极输出保护电流的增大,有套管处管道阴极保护电位越负移,管道越容易受到保护。

In this article,the effect of the casing on the cathode protection potential of the oil pipeline was studied through numerical simulation,experimental simulation and on-site survey.The results show that firstly,the casing shields cathodic protection current of pipeline surface so as to weaken the cathodic protection.Secondly,when the two ends of the casing are not sealed,the cathode protection current can enter the pipeline section enclosed by the casing,and the cathodic protection will play a certain role,but at this time,the water,soil and other impurities in the external environment will enter the annular space between the casing and the pipeline section,resulting in the pipeline being more prone to corrosion.Thirdly,the greater the electrolyte conductivity in the annular space is,the more negative the pipeline cathode protection potential at the casing place is.Fourthly,in the shallow buried area,the pipeline cathode protection potential at the casing place gradually increases with the buried depth increasing;in the deep buried area,the pipeline cathode protection effect at the casing place is hardly affected.Fifthly,with the increase of the vertical distance of the auxiliary anode,the pipeline cathodic protection potential at the casing place shifts gradually and positively,while the cathode protection potential away from the pipeline at the casing place shifts negatively.Sixthly,with the increase of the anode output protection current,the more negatively the pipeline cathode protection potential at the casing place shifts,the more the pipeline is protected.