EXPERIENCE OF PRODUCED WATER-TREATMENT IN THE NORTH-SEA

This paper describes the experience of the Elf company regarding produ ced water treatment and disposal in the North Sea, It focuses on three fields where difficulties were faced: it evaluates the various treatm ent 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 ob tain a satisfactory quality of the produced water discharged. The cont ribution 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 ups tream treatment and processes, it is still very difficult to anticipat e the correct design of an installation or to extrapolate from laborat ory tests, For these reasons and others, the improvement of performanc e requires extensive effort by operators, process and design engineers in order to improve the quality of effluent discharged. Finally, it e xpounds the limits of the efforts made by industry to reduce the quant ity of hydrocarbons released into the sea or to comply with present re gulations. It emphasizes that not only costs are to be taken into acco unt but also the adverse consequences of a further reduction of the li mit for discharges, if this should happen. Such a measure would lead t o the use of techniques which, in many cases, would increase the total impact of the produced water treatment and the human risk.