井底多相介质中S135钢腐蚀影响因素分析

Analysis of Corrosion Factors of S135 Steel in Multiphase Medium Drilling Environment

模拟空气钻井中高温高压多相介质腐蚀环境,考察了温度、Cl-含量、Ca2+含量、Mg2+含量、空气压力、钻屑量、钻屑粒度、转速、pH值对S135钢的腐蚀影响。结果表明:腐蚀速率随温度、Cl-含量、Ca2+、Mg2+含量、空气压力或转速的升高而增大,在低温或低压下,腐蚀为均匀腐蚀;高温或高压下,呈现非均匀腐蚀现象。随腐蚀介质中钻屑量的增多,钢片磨蚀作用增强,腐蚀速率逐渐增大;钻屑粒度越大,则其磨蚀作用越强,腐蚀越明显;均匀混合的钻屑较单一级配的钻屑对钢片的磨蚀程度大。腐蚀速率随pH值的升高而降低,碱性条件有利于防腐。灰关联分析结果表明,各影响因素作用由大到小依次是:温度>pH值>空气压力>Cl-含量>钻屑量>转速>Ca2+、Mg2+含量>钻屑粒度。

Effects of temperature, Cl^- content, Ca^2+、Mg^2+ content, air pressure, cuttings content, granularity of cuttings, rotate speed and pH value on S135 steel are studied through simulating high temperature and high pressure multiphase medium corrosion environment in air drilling.The results show that corrosion rate increases with increasing of temperature, Cl^- content, Ca^2+、Mg^2+ content, air pressure or rotate speed, presenting general corrosion in low temperature or low pressure and local corrosion in high temperature or high pressure. Corrosion rate and erosion of S135 steel increase evidently with adding cuttings. Corrosion is obvious if sands are thicker and symmetrically mixed. Corrosion rate decreases in high pH environment, and this is in favor of corrosion inhibition. The effect of various factors on the corrosion of S135 steel could be ordered according to gray association analysis from great to small as following: temperature>pH value>air pressure>Cl^- content >cuttings content>rotate speed>Ca^2+、Mg^2+ content>granularity of cuttings.