Cleaner anti-corrosion

April 13, 2000, 10:00 CEST

Non-polluting nitrate is being used by Statoil in a pioneering move to inhibit corrosion in water injection tubing on offshore platforms.

This represents the first time an oil company anywhere in the world has adopted this substance in place of biocides, which are toxic to bacteria.

Its introduction follows a long-standing collaboration with the microbiology institute at the University of Bergen to develop better methods for preventing corrosion in injection lines.

The goal has been to find environment-friendly alternatives to the toxic chemicals added to seawater injected into reservoirs for pressure maintenance, explains Tore Thorstenson, who heads Statoil's core team for production chemicals and well chemistry.

Biocides have been used because bacteria play an important role in causing corrosion, but they failed to work as expected. Researchers decided that nitrate solutions are significantly more effective.

Veslefrikk in the North Sea is the first Statoil field to adopt this substance. Mr Thorstenson says that corrosion due to bacterial action has become a declining problems after 15 months of using the new chemical.

Nitrate solutions are also being utilised today on all three of the group's Gullfaks platforms,

"As we gain more experience with the technology, we envisage that it will be possible to replace biocides on most of our installations," says Mr Thorstenson.