Abstract
Microbicide and nitrate are applied, either alone or in combination, in many seawater injection systems as controls to mitigate microbiologically influenced corrosion (MIC) or reservoir souring or both. Dosing strategies vary widely from field to field. In some fields this may be due to physicochemical conditions within the injection facilities and reservoir that dictate which chemical formulations can be applied. In others, the strategy might be selected and optimised based on which of the problems, MIC or souring, is assessed as the most important in terms of flow assurance. In a few cases, two strategies – one for MIC and one for souring – are applied simultaneously. Studies were undertaken in laboratory mesocosm systems employing fixed film upflow bioreactors and recirculating biofouling rigs with flow cells to develop biofilms representing the reservoir environment and the internal metal surface of the injection system respectively. As chemical treatments strategies for both MIC and reservoir souring mitigation generally require dosing into the topsides water injection system, the aim of the study was to determine if similar control strategies were applicable to both problems.
