Produced water is water produced as a by product along with the oil & gas.
The constituents of produced water are many and varied, with the majority of substances being: Water, hydrocarbons, production chemicals and solids, both suspended and dissolved. These contaminants need to be treated to enable the produced water to be either injected or safely disposed of according to local environmental regulations .
Veolia has developed a range hydrocyclones for the treatment of produced water

Streamliner
STREAMLINER™ de-oiling hydrocyclone is to separate free oil from produced water prior to discharge or injection.

Sandliner
SandLiner desanding hydrocyclone liner to efficiently remove damaging levels of solid particles such as sand, scale and corrosion products present in a produced water stream.