盐水钻井液中G105钢缓蚀剂Njff-Ⅱ

Corrosion Inhibitor Njff-Ⅱ for Carbon Steel G105 in Salt Water Drilling Fluid

江苏油田洪泽、淮阴地区井深超过500-米,地温80℃左右,使用盐水钻井液钻井时G105钢钻具腐蚀严重。在盐水钻井液滤液中G105钢试片的动态腐蚀速度随温度升高而增大,80℃时大于0.6mm/a。参照钻井液滤液配制模拟盐水,按L25(54)正交表安排实验,测得无机离子对G105钢试片80℃静态腐蚀速率影响的排列顺序为:Cl->Ca2++Mg2+>HCO3->SO42-,腐蚀速率在某一Cl-或Ca2++Mg2+质量浓度下出现最大值。筛选出的缓蚀剂Njff-Ⅱ由硅酸钠、钼酸盐、有机胺复配而成,加量0.2%时在盐水钻井液滤液中对G105钢试片80℃动态腐蚀的缓蚀率达88.19%。极化曲线表明Njff-Ⅱ为主要控制阳极反应的混合控制型缓蚀剂。Njff-Ⅱ已投入现场应用。图3表3参4。

In districts Hongze and Huaiyin of Jiangsu oil fields, where the reservoirs are > 5000 m in depth and of temperature ~ 80℃, severe corrosion problems are encountered with G105 steel drilling tools when using salt water drilling fluids (SWDFs).The dynamic corrosion rate (CR) of G105 steel specimens in filtrate of an SWDF increases with temperature raising and is of 0.6 mm/a at 80℃.According to the influencing power upon the static CR of G105 obtained in experiments designed with L25(54) orthogonality table at 80℃in aqueous salts solution simulating the SWDF filtrate in ionic composition, the inorganic ions are arranged in order Cl- >Ca2++Mg2+>HCO3-> SO42-and the CR value goes through a maximum at some concentration of Cl-or Ca2++ Mg2+.The corrosion inhibitor selected, Njff-Ⅱ, is composed of sodium silicate, a molybdate, and an amine in combination and inhibits corrosion of G105 in the SWDF filtrate at 80℃and dynamic conditions by 88.19% at dosage 0.2%.The polarization curves show that Njff- Ⅱis an inhibitor of mixed, dual action and controlling mainly the anode processes.Njff-Ⅱhas been put into field uses.