THE CRUDE OIL EFFECT ON STEEL CORROSION Wettability Preference and Brine Chemistry

摘要

The specific crude oil in crude oil/water production environments has a major effect on the corrosion of steel. The effect of the crude oil on steel corrosion in crude oil/water production is twofold. First, the crude oil changes the brine chemistry, affecting the corrosion rate and protectiveness of the corrosion product layer formed on the steel in much the same manner as synthetic corrosion inhibitors. This effect is predominant whenever 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 a water external mixture. The effect is experimentally measured by corrosion tests in simulated produced water chemically equilibrated with the crude oil. Second, the crude oil affects the tendency of either water or crude oil to wet the surface influencing steel corrosion. This is termed wettability preference. This effect is predominant when the crude oil and produced water are mixed as in turbulent pipe flow and in production tubulars and is particularly significant for corrosion at low water contents. The corrosion rate break (CRB) water content experimentally measures the crude oil effect on wettability preference and steel corrosion in the crude oil/water mixture. Separately, each technique measures part of the total effect of crude oil on steel corrosion in crude oil-water production. Together the techniques define a much more complete picture of the effect of crude oil on steel corrosion behavior. Wettability preference and brine chemistry are two separate issues, and both must be evaluated to get a complete picture of the crude oil effect on steel corrosion.