A newly developed biocide test system allows the testing of biocide dosage strategies for their performance against MIC biofilms under pipeline-simulating conditions. The test system was applied to evaluate the performance of various biocide dosage regimes against a biofilm of a methanogenic Archaea similar to abundant MIC-related microorganisms identified in production systems in the North Sea. The efficiency of each biocide treatment was evaluated based on its immediate effect on the biofilm activity and on its lasting performance the days following biocide injection. Results from the new test system were compared with results obtained from a conventional biocide kill test performed on the same test organism. The results showed that dosage regimes, which proved effective in the conventional biocide test, showed no significant effect towards the methanogenic biofilm when evaluated in the new test system. This emphasizes the risk that even well-tested currently applied biocide dosage strategies may not be effective against MIC-causing biofilms growing on pipeline surfaces. Implementation of the new test system as part of a generic MIC risk management is expected to help operators ensure a good performance and cost-efficiency of biociding strategies prior to implementation in full-scale systems. This work is the conclusion of a three-step program intending to improve identification of organisms in the system, monitoring of the transportation system for bioactivity and MIC and finally improved testing of biocides under controlled conditions.

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