Microbially Influenced Corrosion in Oil Sands Water Handling Facilities

Brackish water drawn from the McMurray and Grand Rapids geological formations is being used increasingly to support the recovery of bitumen from Alberta oil sands by steam-assisted gravity drainage (SAGD); yet, these waters are proving to be surprisingly corrosive. Because continuous availability of water is critical to sustained production, a study was initiated to determine the potential role of MIC in water handling and treatment facilities. Field samples of water and cut-out pipe provided by an operating company were characterized in terms of chemical and microbial activity. Corrosion rates were determined by weight loss and by linear polarization resistance. Microbial community composition was determined by DNA isolation, amplification of 16S genes and pyrosequencing. Results for brackish waters drawn from the McMurray and Grand Rapids formations showed important differences, with the former being generally more corrosive. It appeared that methanogenic archaea contribute to corrosion problems in the upstream piping, whereas sulfate-reducing bacteria contribute downstream from the injection point for a bisulfite oxygen scavenger.