Nitrate treatment is well documented as a mitigation method for reservoir souring, however, field
trials have indicated that increased corrosion could be a possible side effect of nitrate treatment.
This paper describes results from offshore side stream test rigs and laboratory investigation where a
mixture of produced water and aquifer water was treated with nitrate. A corrosion rig was developed
where the different combinations of produced water and Utsira aquifer water were investigated with
respect to corrosion and microbial activity under offshore conditions. Corrosion increased when
nitrate was added in combination with CO2, from 0.01 to > 1 mm year. The microbial community
changed when nitrate was added, and the presence of H2 consuming bacteria indicates that a
cathodic reaction could be a possible corrosion mechanism.