Abstract
Recent years have seen a wide-world increase in the production of acidic crudes rich in naphtenic acids (NAs). The presence of these compounds in crude may lead to two different problems: i)- the so-called naphthenic acid corrosion (NAC), and: ii)- formation of naphthenates (naphthenic acid salts) which can either precipitate or form interfacial active salts (soaps) that are prone to stabilize emulsions. The formation of naphthenates (NAPHs) during the W/O separation process is promoted by the pH increase of the produced water phase brought about by CO2 degassing.
NAC problems are well-understood and advantages in technologies to mitigate them are abundant. In contrast to this, NAPHs problems which are germane to the topside O/W separation settings are themselves a dimly understood problem. However, the combination of tailored chemicals and changes in the processing parameters is the best solution to keep NAPHs problems at bay.
Taking these points as the main rationale this paper presents:- a description of NAPHs problems in the upstream crude oil sector; - a comprehensive description of the NAPHs problems Petrobras has been facing; - the analytical tools suitable to characterize and quantify the presence of NAPHs in the produced fluids; the suite of lab tests to screen chemical additives for field application; the difficulties in sparking actions to modify oil-processing parameters and to injecting chemical on an outsourced FPSO top-side facilities, and; the concert of solutions that have provided the best field results.
This paper concludes with a suggestion that a comprehensive water and crude oil characterization program (including geochemistry studies) is totally necessary to cope with the macroscopic behavior of NAs in actual field conditions.
