Hydrocarbon reservoirs are comprised of natural rock formations which are permeated with a mixture of hydrocarbons and water. Due to their underground nature and temperature, reservoirs are usually under considerable pressure.

As fluid is extracted from a reservoir, the pressure underground often slowly reduces, having the consequence of reducing the flow to the producing well area. In addition, and specific to each reservoir, the rate at which the fluid migrates to the well may also reduce.

Water injection is the action of injecting water into a reservoir to maintain pressure and encourage hydrocarbons to the producing well.

In many situations, the most convenient fluid for injection is the produced water from the well. Injection is also a convenient method of produced water disposal. In an offshore environment, seawater is often the preferred source of injection water.

The quality of the water for injection, from whatever source, will be required to be of a standard that will not cause problems such as plugging and/or scaling of the injection equipment. This is an important issue, especially offshore, where drilling a new well is extremely expensive.

In addition, because a reservoir is effectively sterile, injecting water containing oxygen and bacteria can cause'souring' of the reservoir. A'sour' reservoir is one where there is the presence of hydrogen sulphide (H₂S) in the hydrocarbons.

Souring reduces the value of the produced hydrocarbons and requires expensive production equipment and materials to cope with the aggressive nature of the produced fluids.

Typical contaminants that need to be removed from injection water are:

• Hydrocarbons
• Solids
• Scaling compounds such as sulphate
• Sulphate reducing bacteria (SRB)

The VWS Westgarth turnkey package

VWS Westgarth engineers, procures and project manages the complete seawater system including:

• Seawater Lift Pumps and Coarse Filtration
• Chlorine generation
• Seawater cooling systems
• Process pumps
• Pre-treatment systems (membrane and traditional media)
• Sulphate Removal Package (FilmTec (TM) brand SR-90 MEMBRANE ELEMENTS)
• Deaeration packages (vacuum, gas strip and nitrogen blanketing)
• Chemical storage, dosing and injection (inc. nitrogen generation and blanketing)
• System Healthcare

VWS WESTGARTH IS THE WORLD LEADER IN SULPHATE REMOVAL SYSTEMS

Downloads in PDF format

• Buzzard (251,700 BPD single lift module SRP complete with membrane filtration pre-treatment system) 
  
• FPSO Capixaba (138,400 BPD multi skid SRP complete with cartridge filtration) 
  
• FPSO Greater Plutonio (415,300 BPD multi module SRP complete with rapid velocity media pre-filtration) 
  
• P51 (283,020 BPD single lift module complete with cartridge filtration)
  
• P52 (301,890 BPD multi module SRP with cartridge filtration)
  
• P53 (245,300 BPD single lift SRP module complete with cartridge filtration) 
  
• FPSO Vitoriá (138,400 BPD single lift SRP module complete with multi media and cartridge filtration)
  
• FPSO Mondo (125,000 BPD multi skid SRP complete with cartridge filtration) 
  
• FPSO Saxi-Batuque (150,000 BPD multi skid SRP complete with cartridge filtration) 
  
• Agip Tiffany (100,000 BPD single module SRP) 
  
• FPSO Brasil (90,000 BPD single lift SRP complete with cartridge filtration) 
  
• Soroosh Nowrooz (21,384 BPD single module SWRO complete with dual media filtration) 
  
• South Arne (135,000 BPD multi skid SRP complete with dual media filtration) 
  
• FPSO Gimboa (60,000 BPD single lift module complete with dual media filtration) 
  
• FPSO Espirito Santo (75,000 BPD multi skid SRP complete with cartridge filtration)