Imidazolium-based ionic liquids as an anticorrosive agent for completion fluid design

Most of the onshore and offshore oil and gas reservoirs are facing operational challenges due to high temperature and high salinity, thus requiring advanced techniques for realizing the expected oil recovery with the use of specially designed chemicals. During oil and gas well development, completion fluids, which are solids-free liquids, are used to complete an oil or gas well. Completion fluids consisting of brines are primarily used for oil and gas well stabilization and are corrosive in nature. There is a need to develop additives to be added with completion fluids to address the corrosive nature. The present investigation involved the usage of two imidazolium ionic liquids (ILs) as corrosion inhibitors for mild steel in various completion brine (CaCl2, HCOOCs and ZnBr2) fluids. The study was performed using various techniques, such as, potentiodynamic polarization, weight loss measurements and exposure studies. All the above techniques showed promising results which indicated that the ILs as corrosion inhibitors used were of the mixed-type following both physisorption and chemisorption over the mild steel surface. Among the two inhibitors studied here, 1-octyl-3-methyl imidazolium chloride ([OMIM]+[Cl]-) with longer alkyl chain exhibited better inhibition efficiency and much lesser corrosion rate than 1-butyl-3-methyl imidazolium chloride ([BMIM]+[Cl]-) with a shorter alkyl chain. The results obtained from various methodologies indicate that ionic liquids can be explored to develop anti-corrosive completion fluids suitable for oil and gas reservoirs.