Since the Paris Commission has taken its first measures regarding the discharge of produced water from offshore installations into the North Sea at the end of the 1970s, the provisional performance standard set at that time has remained unchanged. In fact that provisional performance standard (limiting the content of oil at 40 mg per litre of water discharged) was a challenge, and industry spent billions of $US to treat the billions of cubic meters of produced water which have been discharged since then. It led to the development of new treatment techniques, the prominent one being the hydrocyclones in the 1990s.

Measures taken by OSPAR in 2000 regarding chemicals used and discharged offshore and in 2001 regarding the management of produced water dramatically changed the picture, giving an impetus to development of new techniques - some of which being now fully implemented-,to reconsider water management, shut-off techniques, and last but not least, re-injection, a technique which, for many reasons, has been less used in the North Sea than in other regions of the world.

The global average oil content of the water discharged in the North Sea is significantly lower than the upper limit set by the regulators. Nevertheless, not only some installations still face serious difficulties to meet this old performance standard, but the measures taken by OSPAR at the beginning of the 2000s actually go far beyond that standard, create constraints on compounds in produced water other than aliphatic hydrocarbons, and development of new technologies as well as a review of the approach of the operators of produced water treatment and disposal routes need to be dramatically reconsider.

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