Performance Study of Corrosion Inhibitors for CO2 Corrosion on Pre-Corroded Carbon Steel

CO2 corrosion is one of the major problems in the oil and gas industry specifically the effect it gives to the integrity of onshore and offshore equipment. Therefore, several methods have been developed to prevent this type of corrosion and this particular work will be focusing on the application of corrosion inhibitors on the operation of pipelines which exposed to high concentrations of carbon dioxide. However, corrosion inhibitor is usually injected when corrosion already occur on the pipelines and it is believed that the pre-corrosion condition will affect the performance of inhibitors. Thus, the objective of this project is to measure the performance of inhibitors on the pre-corroded carbon steel. Additionally, this project also will find out the effect on environment specifically the pH value to the performance of corrosion inhibitors. So, several test studies have been developed to achieve the targeted objective and all experiments were conducted by using Linear Polarization Resistance (LPR), Electron Impedance Spectroscopy (EIS) and Custom Sweep techniques. Additionally, the amount of injected corrosion inhibitors were increased to 100ppm to know the effect in reducing the corrosion rate. The result from this research indicated the 25ppm corrosion inhibitors managed to reduce the corrosion rate at the first five hours after the injection. However, the corrosion rate increased back since the amount is not enough to provide full protection for 48 hours period of time. In contrast, 100ppm of corrosion inhibitors resulted in efficient corrosion rate reduction which implied that the amount of injected CI affect the corrosion rate very much.