Water that can be found in an off-shore rig.
1.- Ballast water.
2.- Displacement water.
3.- Drainage water.
4.- Production water.
5.- Desalting water.
6.- Condensed water.
7.- Re-produced injection water.
8.- Production of desalted water.(Ion exchange)
9.- Human use water.
10.- Geological trap water, or formation water.
During production, the petroleum extracted is a mixture of hydrocarbons, gases and water. These must be separated at the rig before pumping onshore. The water is a complex saline solution that may contain highly toxic cations and electrolytes. Up to now, this water was discharged directly into the sea.
Se details in
OSPAR Recommendation 2001/1 for the Management of Produced Water from Offshore Installations

http://www.ospar.org/documents/dbase/decrecs/recommendations...