Detection of Microbially Influenced Corrosion in Real World Samples Using Zero-Resistance Ammetry

As natural gas production in the United States continues to increase, the abundance of transmission pipelines will increase similarly to accommodate the productivity. These pipelines are susceptible to internal microbially influenced corrosion (MIC), which is exceedingly difficult to detect. First, MIC is, by nature, a localized process, and localizing damage is nearly impossible with “bulk” pipeline interrogation techniques. Second, highly specialized techniques are required to reliably diagnose MIC. Third, detection of internal MIC requires removal of samples from the pipeline for analysis and therefore, downtime. Fourth, evidence of MIC may not be detectable until the system is “infected” beyond recovery. This poster describes a method for detecting, mitigating and/or locating internal pipeline corrosion, through the development of an innovative electrochemical “signal” based approach to detect and quantify MIC in natural gas and oil transmission pipelines.

This electrochemical approach involves zero-resistance ammetry (ZRA) measurements along a pipeline that can be used to detect MIC. The ZRA approach could be deployed along entire pipelines and would sensitively detect a broad range of in-situ microbiological processes. To test ZRA as an MIC monitoring tool, we carried out split chamber ZRA (SC-ZRA) incubations that entailed deployment of two steel working electrodes (WE1 and WE2) in chambers electrochemically connected by a salt bridge. Subsequently, one chamber is inoculated with the sample while the other is sterilized sample devoid of biological matter, and ZRA and potential measurements were made with evaluations of microbiological activities. Current direction and magnitude can be indicative of the mechanisms and extents of MIC. The SC-ZRA setup mimics the heterogenous biofilm coverage of metal surfaces that leads to MIC, and we propose to use it to establish the electrochemical signatures of MIC. We used real-world oil samples of produced water and separators obtained from Hilcorp, Alaska to inoculate SC-ZRA and incubate them under conditions representative of pipeline fluids. We then specifically evaluated the current magnitude, direction and extent of corrosion and validated the results using weight-loss analysis.