The water injected into the reservoir, that provides pressure to increase and stimulate oil production, requires filtering, deoxygenation and biociding.
The primary extraction of oil from a producing well is a natural process based on a pressure drop. When the underground pressure becomes insufficient to force oil, the production rate drops. Water injection into the reservoir is able to provide a pressure increase to stimulate oil production, the secondary recovery.
In offshore producing facilities, seawater is the most convenient source of water for injection. Nevertheless, it generally requires filtering, deoxygenation and biociding even when the seawater intake is placed at an appropriate depth.
Cannon Artes is familiar with providing different kind of filters in order to remove any impurities, including shells and algae. The filtration rate strongly depends on reservoir requirements so as not to block the pores of the reservoir.
- Media filters with different beds with various sizes of sand granules are a commonly used filtration technology to remove solid impurities from the water.
- As a very efficient alternative, Ultrafiltration (UF) is now widely employed to achieve the quantitative removal of solids, colloids and bacteria.
- After filtration, water may be treated on Sulphate-Removal-Unit (SRU) based upon Nano Filtration (NF) membranes. Removal of Sulphates prevents scaling and souring caused by Sulphate Reducing Bacteria.
Before injection into the reservoir, water must be de-oxygenated. This is essential to:
- eliminate pipe corrosion
- avoid biofouling
- prevent reservoir souring (which reduces the value of the oil due to undesirable biological byproducts
- improve Chemically Enhanced Oil Recovery (CEOR) affecting the polymer/water interface.