Electrochemical Study of Corrosion Inhibition of Carbon Steel During Oil/Water Intermittent Wetting

Abstract

Application of corrosion inhibitors in production systems containing oil and water is an economic method to protect carbon steel against internal corrosion. This study investigates how intermittent oil/water wetting of such a steel surface, simulating multiphase flow phenomena, impacts corrosion inhibition in exploration-production (high salinity with CO2) and refinery (low salinity without CO2) environments. The employed corrosion inhibitor was a pyrimidinium-type model compound, its effectiveness against corrosion being characterized using linear polarization resistance measurements and electrochemical impedance spectroscopy. Experimental results demonstrated that the presence of an aliphatic oil promotes corrosion inhibition in the exploration production condition, but failed to do so in the refinery condition. Electrochemical impedance spectroscopy revealed two different protection mechanisms in the presence of oil between the two environments. The inhibitor layer in refinery condition with oil was different from in the simulated exploration production environment after oil wetting. Results also demonstrated that the inhibitor in this study was physically adsorbed on the surface steel via electrostatic attraction. Anions, identified as chloride ions, played a critical role in inhibitor adsorption.

Experiments and Molecular Simulations to Study the Effect of Surface-Active Compounds in Mixtures of Model Oils on CO2 Corrosion during Intermittent Oil–Water Wetting

“…Previous studies have shown that surfactant compounds interact with the oil molecules at the steel interface and consequently provide corrosion mitigation. The CO 2 corrosion mitigation effect is dependent on the chemical structure of the molecules, as well as the physical properties of the aqueous phase and operational conditions . It has also been shown that surfactants mostly block the active sites of the surface and reduce the corrosion rate, and in a few cases, the adsorbed layer on the surface is thick enough to provide a mass transfer barrier.…”

“…The CO 2 corrosion mitigation effect is dependent on the chemical structure of the molecules, as well as the physical properties of the aqueous phase and operational conditions. 62 It has also been shown that surfactants mostly block the active sites of the surface and reduce the corrosion rate, 63 and in a few cases, the adsorbed layer on the surface is thick enough to provide a mass transfer barrier. Although, caution needs to be taken in interpreting the results of these works since they focus on the adsorption of inhibitor surfactants without the presence of the hydrocarbon phase.…”

Synthesis of a resorcinol-based derivative as a corrosion inhibitor for low-carbon steel in 0.5 mol L−1 HCl medium: chemical, electrochemical, and theoretical aspects

“…DMIH molecules can therefore adsorb on the metal surface. 63,64 The capability of an inhibitor to adsorb depends on a variety of factors, including its molecular size, chemical structure, the kind of metal and its charged surface, and charge distribution throughout the inhibitor molecule. Two types of adsorptions, chemisorption and physisorption, were considered.…”