This paper describes the experience of the Elf company regarding produced water treatment and disposal in the North Sea, It focuses on three fields where difficulties were faced: it evaluates the various treatment techniques used (plate separators, hydrocyclones, vapour stripping units, injection into a disposal well), the reasons for the problems encountered during the life of these fields and the efforts made to obtain a satisfactory quality of the produced water discharged. The contribution of recent or new technologies put on the market is discussed, It shows that, because of the nature of the effluents to be treated, and the fact that produced water characteristics depend largely on upstream treatment and processes, it is still very difficult to anticipate the correct design of an installation or to extrapolate from laboratory tests, For these reasons and others, the improvement of performance requires extensive effort by operators, process and design engineers in order to improve the quality of effluent discharged. Finally, it expounds the limits of the efforts made by industry to reduce the quantity of hydrocarbons released into the sea or to comply with present regulations. It emphasizes that not only costs are to be taken into account but also the adverse consequences of a further reduction of the limit for discharges, if this should happen. Such a measure would lead to the use of techniques which, in many cases, would increase the total impact of the produced water treatment and the human risk.
