This paper presents an investigation on the performance of corrosion inhibitors in reducing corrosion loss of N80 steel coupons at high temperature in 15 wt.% and 28 wt.% HCl solutions. This work studied the effect of temperature and acid concentration on corrosion inhibitor performance and provided an efficient corrosion inhibitor for application at elevated temperature of 120°C. Five corrosion inhibitors including Mannich base derivatives and pyridine quaternary ammonium salt were selected. The corrosion rates of N80 steel in concentrated HCl solution with and without corrosion inhibitor were evaluated by gravimetric method and the surface of steels after corrosion tests were characterized by microscopy. The results showed that the corrosion rate of N80 steel in 15 wt.% HCl at 120°C was much higher than that at 90°C. As a result, higher concentration of corrosion inhibitor was needed to reduce the corrosion to an acceptable value of 0.05 lb/ft2. The corrosion rate could be reduced to 0.0035 lb/ft2 in 15 wt.% HCl at 120°C. Increasing the HCl concentration to 28 wt.% at 120°C, the corrosion inhibitor concentration required was several times as much as the dosage for 15 wt.% HCl.
A suitable acid package in matrix acidizing application is very important to the stimulation employed to improve the productivity of carbonate reservoirs. Typically, concentrated acids between 5 and 28 wt% are used and the most used mineral acid for carbonate acidizing treatment is hydrochloric acid (HCl) 1,2. A significant challenge of acidizing treatment is corrosion loss of metal tubulars due to the high reactivity of acid and metal, especially at high temperatures. Corrosion inhibitors are needed to reduce the corrosion loss of steel surface of facilities exposed in acidic environment. Most research focuses on corrosion inhibition of steel materials in HCl solution at temperate lower than 100°C 2. A few studies reported the corrosion control at higher temperature 3,4. In the absence of corrosion inhibitors, the general corrosion rate can increase exponentially with increasing temperature 5,6. It is still an industrial challenge to have a corrosion inhibitor to efficiently inhibit corrosion on carbon steel in highly concentrated HCl at elevated temperature above 100°C.
