Abstract
It is observed that some crude oils show inhibitive properties, supposedly from components that pass from the oil phase to the water. In laboratory tests this phenomenon is observed by lower corrosion rates in the aqueous phase after contacting the water with crude oil, without any direct contact between the crude and the steel surface, as in a stratified flow regime.
Taking advantage of this inhibitive effect might allow delaying the start-up of inhibitor injection and / or reducing inhibitor dosage, i.e. an environmental and economical benefit.
The nature of compounds that pass into the water phase and the main parameters influencing this behavior (water’s pH and salinity, crude composition) are investigated.
Neither existing data from the literature nor additional results relate this inhibitive behavior to individual compositional factors of the crude (SARA, TAN, TBN1, density…).The effect of temperature and water-cut is minimal.
We are still far from being able to model this inhibitive effect from crude components, as key factors are not well identified or understood. Lab testing to evaluate this inhibitive effect is thus presently the sole practical way to take credit of it, assuming that a representative methodology and representative crude samples are available. This representativeness is presently our main concern..Until these inhibitive effects are better understood, it is our policy not to count on them to delay or prevent the application of inhibitor treatments.
