【作者】 宋学锋；

【导师】 周永璋；

【作者基本信息】 南京工业大学 ， 材料学， 2006， 硕士

【摘要】 在钻井过程中,钻具的腐蚀相当严重,并且随着钻井方向向纵深发展,温度、压力、井层地质结构的变化等各种因素使得钻具的腐蚀破坏日趋严重。江苏油田承钻油井过程中发现钻具腐蚀严重,前人通过对钻具在钻井液中的腐蚀产物进行EDS分析,发现腐蚀产物主要成分是Fe2O3,从而推断出钻井液对钻具的腐蚀主要是氧的去极化所致。本文主要是研究钻具在钻井液中遭受腐蚀的影响因素,并筛选出适用的缓蚀剂,通过复配改进缓蚀剂的缓蚀效率,减缓腐蚀速率。通过阴、阳极极化曲线探讨了钻具在腐蚀过程中的一些影响因素。研究发现,随着钻井液pH值的增大,钻具钢的腐蚀速率减小。随着温度的升高,阳极区的致钝电流明显增大,说明温度升高,钝化膜形成的难度增加。另外,腐蚀速度随盐含量的增加先变大后减小,可能是当盐含量增到一定程度后阻滞了介质中的溶解氧向金属表面扩散,故降低了腐蚀速度。泥浆中各离子对腐蚀速率影响顺序为:Cl->S2->HCO3-> SO42-,Cl-对腐蚀的影响最大,滞后环实验亦证明了Cl-含量的增加,局部腐蚀的敏感性增加,且保护电位有所降低,耐蚀性降低。从旋转动态模拟挂片实验中发现,随着转速的增加,腐蚀速率逐渐增加;随着腐蚀时间和通气量的增加,腐蚀速率先增大后减小;随着温度的增加,腐蚀速率也增大,且从腐蚀速率的大小可以看出,各因素的影响顺序:温度﹥转速﹥腐蚀时间﹥通气量。通过线性极化法筛选出单组分缓蚀效果较好的钼酸钠、硅酸钠、高锰酸钾、月桂酰肌氨酸钠以及有机胺D为复配的基本配方。利用极化曲线法评定复合缓蚀剂的缓蚀效果,并研究其缓蚀机理。研究表明,复配后的缓蚀效果比未添加缓蚀剂或添加单组分缓蚀剂时要强,说明复合缓蚀剂各组分之间具有一定的协同缓蚀效果,能够有效地在金属表面形成具有互补性的保护膜,能有效提高自腐蚀电位,降低腐蚀电流。通过线性极化法进一步验证各复合缓蚀剂的缓蚀效率,并用交流阻抗法对缓蚀率大于90%的配方进行研究。结果表明,复合缓蚀剂能够在金属表面形成屏蔽性能良好的比较完整的保护膜,有效地阻止腐蚀介质向金属表面扩散和降低电荷传递的流量,更多还原

【Abstract】 The corrosion of drill tools is a serious problem in the drilling engineering. It will become even worse when the drill tools have gone deeper and the surroundings have changed, such as temperature, pressure and geologic structure and so on. Drill tools have corroded seriously when they are used in the engineering of oil exploitation by Jiangsu Oil Field. It is concluded by EDS(Energy Dispersive Spectroscopy) analysis on corrosion products of drill tools in drilling fluid that the main component of the corrosion products on local drill tools is Fe2O3. Thus the corrosion of drill tools is mainly caused by the depolarization of dissolved oxygen. Factors on corrosion were studied. Inhibitors that could be used in the practice were selected. Efficiencies of composite inhibitors were improved.Results tested by polarization curves showed that the corrosion rate decreased with the increasing of pH value. The passive current in the anodic area had obviously increased with the increasing of temperature. This proved that it would be more difficultly for the passive film to form with the increasing of temperature. In addition, the corrosion rate increased firstly and then decreased with the increasing of the salt content. The high salt content could hinder oxygen from arriving the metal surface and therefore, there was a decrease in the corrosion rate. It could be inferred from the results the sequence of the effect on corrosion rate is Cl->S2->HCO3->SO42-. The influence of Cl- on the corrosion is the greatest. Results tested by potentiadynamic polarization curves proved that the sensitivity of corrosion partly increased with the increasing of Cl- content. The protective potential and corrosion resistance decreased.Results from the weight loss test showed that the corrosion rate increased with the increasing of the agitating speed, temperature. The corrosion rate increased firstly and then decreased with the increasing of corrosion time and quantity of oxygen. The results indicated the sequence of the effect on corrosion rate is temperature> agitating speed>time> quantity of oxygen.Sodium molybdate, sodium silicate, potassium permanganate, sodium更多还原