Surface water contains biological constituents (primarily bacteria) that can contaminate the waterinjection system. Because bacteria have the ability to multiply rapidly into colonies, they can:
- cause plugging of surface and downhole equipment and injection-well formations
- Promote corrosion of surface piping and downhole tubulars.
- generate H2S that can cause pitting corrosion
Therefore, it is essential to develop a means to control the growth of bacteria in surface-water-injection systems. Bacterial growth is controlled mainly by chemical biocides, which may be added directly or produced in-situ from seawater. Direct-added chemicals are covered in Water treating chemicals.