双曼尼希碱酸化缓蚀剂的合成及性能

Synthesis and properties of double Mannich base as a corrosion inhibitor for acidification

酸化是提高采收率的一项有效技术措施,为防止酸液对油管及各种设备造成腐蚀,必须向酸液中加入缓蚀剂。以硫脲、苯甲醛和苯乙酮为原料,采用两步反应合成出一种双曼尼希碱,将其作为酸化缓蚀剂。参照中华人民共和国石油天然气行业标准SY/T 5405—1996,以常压静态腐蚀速率为评价指标,用正交实验法对主剂的第二步合成工艺条件进行优化,试验条件下获得的最佳合成工艺条件为:中间体、苯甲醛、苯乙酮摩尔比为1∶1∶1;反应温度110℃;反应时间4 h。经测试,该缓蚀剂的适用条件为:酸化用盐酸质量分数低于25%,井下温度低于75℃,最佳加入量0.7%~1.0%。动电位极化曲线表明,该缓蚀剂是以抑制阴极反应为主的混合型缓蚀剂。吸附特性表明,该缓蚀剂在N80钢表面的吸附行为符合Langmuir吸附等温式,吸附为吸热、自发、熵增的过程,总熵增加是产生吸附的一个重要驱动力。在15%HCl中加入1%该缓蚀剂,60℃下N80钢片的腐蚀速率降至0.986 g/(m2·h),远优于一级缓蚀剂标准,显示出良好的应用前景。

Acidification is an effective measure of enhanced oil recovery. To prevent the oil pipeline and process equipment,corrosion inhibitor should be added into acid solution. With thiourea,benzaldehyde and acetophenone as raw materials,the double Mannich base was synthesized through two-step reaction,and used as acidizing inhibitor. With referenced to the petroleum and natural gas industry standard of P. R. China ＂SY/T 5405-1996＂,atmospheric static corrosion rate was used as theexperimental evaluation indexes,the synthetic conditions of the second reaction were optimized in terms of orthogonal test method. The optimal synthetic conditions gained on experimental condition are as follows： the molar ratio of intermediate,benzaldehyde and acetophenone is 1 ∶ 1 ∶ 1,reaction temperature 110 ℃ and reaction time 4 hours. The optimal applicable conditions of the inhibitor are as follows：hydrochloric acid concentration below 25%,well temperature below 75 ℃,dosage of it from0. 7% to 1. 0%. The potentiodynamic polarization curves showed that it is a mixed-type inhibitor predominantly act on cathodic area. The adsorption characters of it on N80 steel are endothermic,spontaneous,entropy increasing process and adsorption behaviors followed Langmuir isotherm. The increase of entropy is the main driving force of absorption. When 1% of this corrosion inhibitor is added into 15% HCl,the corrosion rate of N80 steel can be reduced to 0. 986 g per square meter and per hour（ at 60 ℃）,which is much better than the first-grade corrosion inhibition performance of industry standard. This indicates a good prospect of industrial application.