应用动电位扫描和失重法研究HCO3-对油气田CO2腐蚀的影响.实验表明,当HCO3-浓度低于0.042 mol/L时,随着HCO3-浓度的增加,溶液pH升高,H+的还原速率(阴极电流密度)下降;HCO3-浓度增至0.126 mol/L时,溶液中的H2CO3、HCO3-的直接还原占主导地位,故阴极过程随HCO3-浓度的上升而加速,对阳极过程,在HCO3-浓度低于0.042 mol/L下,主要为活化过程,而且其阳极溶解电流(密度)随HCO3-浓度的增加而下降;HCO3-浓度增至0.126 mol/L时,阳极过程出现明显的活化-钝化行为.高温高压腐蚀试验显示,材料的腐蚀速率随介质HCO3-浓度的增加而下降.SEM、EDS、XRD分析表明,在较低的HCO3-浓度下,腐蚀产物膜的主要成分为FeCO3晶体,HCO3-浓度较高时,则腐蚀产物主要为Ca、Mg的化合物,并形成Ca(Fe,Mg)(CO3)2复盐.在高pH值下,Ca2+、Mg2+比Fe2+更容易沉积.
The effecs of HCO_3~-concentration on CO_(2) corrosion in gas and oil fields were investigated by carrying out potentiodynamic scans and weight loss tests.Potentiodynamic polarization curves showed that the cathodic current density decreased with cm increase of HCO_3~-concentration when [HCO_3~-] was lower than 0.042(mol/L.)The cathodic reations were promoted by increasing [HCO_3~-] when it reached 0.126 mol/L,(Anodic) behavior was an active process at low er [HCO_3~-] concentration and the anodic current density decreased with the increase of [HCO_3~-] concentration.An evident active-passive behavior exhibited in anodic process at 0.126 mol/L HCO_3~-.Under high pressure and high temperature,the corrosion rate of steel X65 decreased with the increase of HCO_3~-concentration while pH increased.SEM,EDS,XRD results of the corrosion scales indicated that a typical FeCO_(3) crystallite was found at low HCO_3~-concentration but Ca(Fe,Mg)(CO_(3))_(2) at high HCO_3~-concentration.Ca~(2+),Mg~(2+) precipitated prior to Fe~(2+) at high pH value.
[1]LU M inxu(路民旭),BAI ZHenquan(白真权),ZHAO X inwe i(赵新伟),et al.Actuality and typ icalcases for corrosion in theprocess of extraction,gather-ing,storgage and transm ission for oil and gas[J].Corrosion&Protection,2002,23(3):105~113.
[2]Kerm an iM B,Morshed A.Carbon d ioxide corrosion inoil and gas production-a compend ium[J].Corrosion,2003,59(8):659~683.
[3]V idem K,Kvarekval J.Corrosion of carbon steel in car-bon d ioxide-saturated solutions contain ing sm all a-mounts of hydrogen sSu lfide[J].Corrosion,1995,51(4):260~269.
[4]Hong T,Sun Y H,Jepson W P.Study on corrosion in-h ib itor in large p ipelines under mu ltiphase flow usingEIS[J].Corrosion Sc ience,2002,44:101~112.
[5]V idem K,Koren A M.Corrosion,passivity,and p ittingof carbon steel in aqueous solutions of HCO3-,CO2,and C l-[J].Corrosion,1993,49(9):746~754.
[6]Jasinsk i R.Corrosion of N80-type steel by CO2/waterm ixtures[J].Corrosion,1987,43(4):214~218.
[7]XU L im ing(许立铭),DONG Zhehua(董泽华),FAN Hanxiang(范汉香).E ffect of CO2,HCO3-onthe corrosion of carbon steel in oil and gas fields pro-ductive water[J].Natural Gas Industry,1996,16(4):57~60.
[8]Ogundele G I,W h iteW E.Som e observations on corro-sion of carbon steel in aqueous environm ents contain ingcarbon d ioxide[J].Corrosion,1986,42(2):71~78.
[9]Nesic S,Postlethwaite J,O lsen S.An electrochem icalmodel for pred iction of corrosion ofm ild steel in aqueouscarbon d ioxide solutions[J].Corrosion,1996,52(4):280~294.
[10]PAN ZHou lu(潘兆橹).Crystallography and M ineral-ogy(next)[M].Be ijing:geology press,1994.247~256.
