A laboratory flow loop is used to evaluate the ability of an on-line, electrochemical, biofilm-activity probe to monitor biofilm activity in synthetic oilfield brine and correlate its activity to localized pitting corrosion. In addition, bio-traps containing porous polymer beads for trapping biomass are evaluated as a rapid means to evaluate biofilm community structure using phospholipid fatty acid (PLFA) and DNA analysis. Results suggest that applied current as measured by the electrochemical probe can be used to detect biofilm activity in produced oilfield brine and can be used to evaluate the effectiveness of biocide treatments. However, biofilm activity did not always correlate with pitting corrosion conditions. Biofilms collected by biotraps during periods of pitting and non-corrosive conditions, however, displayed distinctly different microbial communities as determined by PLFA and DNA analysis. Furthermore, the biofilm microbial communities in bio-traps and on metal coupons were similar, except during biocide application, suggesting that bio-traps could be used as a rapid means to evaluate biofilm community structure on metal surfaces.
Keywords: Monitoring, electrochemical, on-line, bio-traps, MIC, oilfield brine