Offshore Water Treatment

Definition: Produced water is water trapped in underground formations and brought to the surface along with the oil or gas being extracted. The amount of water produced increases as oil and gas wells become exhausted.

For many years produced water from offshore operations was disposed of directly into the sea with little or no treatment. This practice has been progressively legislated against and producers now seek the services of specialist companies, such as VWS Oil & Gas, to develop solutions that remove pollutants such as salts, suspended and dissolved solids, volatile compounds, organics, ammonia, hydrogen sulphide and oil, prior to disposal or re-injection into the reservoir.

Oil / Water separation

• STREAMLINER ™ De-oiling hydrocyclones
• De-sanding hydrocyclones
• Cophase ™ Compact flotation units (CFU)
• Sand washing

Specific treatments

• Sulphate Removal Process (SRP) including nanofiltration
• Deaeration
• Insoluble hydrocarbons removal
• BTEX, dissolved and dispersed hydrocarbons removal (<0,1 ppm): MPPE systems

General treatments:

• Multimedia filters (Fe, Mg, TDS removal) / cartridge oil adsorption filters
• Activated carbon filtration
• Softening
• Membranes: ultrafiltration, microfiltration, nanofiltration and reverse osmosis

In situations where crude oil has to be desalted or dehydrated, the processes employed require a reliable supply of high quality water known as wash water. The most practical method of producing this in an offshore environment is via seawater reverse osmosis (SWRO).

VWS Oil & Gas designs, engineers, procures and project manages the complete water treatment system including:

• Feed pumps
• Coarse and fine filtration pre treatment
• Chemical Dosing
• Membrane Package
• CIP System
• After-sales Service

Aquatic organisms transported via the ballast water of ships are considered to pose a major environmental threat to the world's oceans and seas. Sustainable development and forthcoming legislation are key drivers for offshore oil producers to ensure that their ballast waters are treated correctly before being disposed of. Veolia Water Solutions & Technologies specialist subsidiary, RWO, offers various solutions including CleanBallast™ for onboard ballast water treatment and disinfection via Ectosys™.