The chemical components of a crude oil have been shown to significantly affect steel corrosion in crude oil production. This effect has shown a wide variability in the way the crude oil alters the corrosion of carbon and low alloy steel in both sweet and sour crude oil/water production including the corrosion rate corrosion morphology and protectiveness of the corrosion product layer formed on the steel. The effect is observed when a separated water phase is in contact with the steel such as stratified pipe flow and the bottom of production separators or when the crude oil and produced water are in an intimate mixture such as in turbulent pipe flow and production tubulars. The crude oil effects can influence the tendency of either water or crude oil to wet the surface termed “wettability preference” and certain organic chemicals in the crude oil can directly affect the corrosion rate and morphology.The work reported here details the extent of the diverse effects different sweet and sour crude oils have on the resulting steel corrosion rates and morphology. Experimental evaluation of the effect of a crude oil on steel corrosion is used to define the range of these effects in mixtures of a specific crude oil and produced water. The effect of the crude oil on corrosion ranges from low general corrosion rates with as much as 70% produced water in sweet crude oil production to severe localized corrosion with 1% produced water in sour crude oil production. The results provide a picture of the broad effect of crude oil on steel corrosion in a production environment.While there has been progress in understanding the effect of crude oil on steel corrosion the details of the influence of crude oil chemistry are still under investigation. Due to the number and variation of polar organic compounds contained in a crude oil possible synergistic effects and the variability in these compounds from crude oil to crude oil relating specific compounds to their effect on corrosion is extremely difficult at best. Applying these data to all crude oils is an exercise in futility. Each crude oil is unique.KEYWORDS: corrosion crude oil steel produced water corrosion morphology crude oil chemistry carbon dioxide sweet hydrogen sulfide sour.
