Toward the Mechanism of Corrosion in Crude Oil: A Study Using Vibrational Spectroscopic Techniques at Elevated Temperatures

Abstract

Naphthenic acid, a significant cause of corrosion of carbon-steel in crude oil, has been investigated at elevated temperatures using vibrational spectroscopic methods (Raman and Fourier transform infrared (FT-IR)). Unlike earlier reports of studies at ambient temperatures, these elevated temperature experiments performed on a series of carboxylic acids having structures similar to naphthenic acid components in crude oil and on a commercial naphthenic acid mixture show a progressive increase with increasing temperature in the concentration of monomer over the multimers, which drives the formation of iron naphthenate. This observation forms a reasonable basis for proposing a mechanism of corrosion in crude oil at temperatures closer to the boiling point of naphthenic acids, which proceeds through the acid monomer.

An Acoustic Microbalance Study of High-Temperature Naphthenic Acid Corrosion of Common Iron-Alloying Elements

“…14 Fourier transform infrared spectroscopy (FTIR) studies were performed using the same method as reported in previous papers. 8,12 Additional experiments were conducted to determine the NA corrosion behavior of bulk samples that were stripped of their surface oxides in situ. The tests were conducted on macro-sized samples and the extent of corrosion was investigated by observations in a SEM.…”

“…The rapid decrease in corrosion rate with time was a result of depletion of acid from the solution, as was indicated by FTIR measurements of the test solution taken after completion of the experiment. 12 The zinc surface, shown in Figure 10, displayed evidence of uniform corrosion.…”

“…12 In the present study, the individual behavior of a few important alloying elements in high-temperature oil containing NA was investigated. The gallium orthophosphate crystal microbalance was used as an ultrasensitive method (mass sensitivity ∼0.3 ng/Hz) to determine the corrosion behavior of these elements in corrosion tests of short duration.…”

Water treatment technologies for the remediation of naphthenic acids in oil sands process-affected water

“…3. NA corrosion mechanism proposed by Chakravarti et al [28]. The mechanism shows that under high temperature conditions, NA multimers may dissociate and complex with metal ions present at the water-metal interface.…”

“…3) [28]. Three types of complexation have been proposed: bidentate bridging, bidentate chelate, and monodentate.…”