title: Microbially Enhanced Oil Recovery by Sequential Injection of Light Hydrocarbon and Nitrate in Low- And High-Pressure Bioreactors.
abstract: Microbially enhanced oil recovery (MEOR) often involves injection of aqueous molasses and nitrate to stimulate resident or introduced bacteria. Use of light oil components like toluene, as electron donor for nitrate-reducing bacteria (NRB), offers advantages but at 1-2 mM toluene is limiting in many heavy oils. Because addition of toluene to the oil increased reduction of nitrate by NRB, we propose an MEOR technology, in which water amended with light hydrocarbon below the solubility limit (5.6 mM for toluene) is injected to improve the nitrate reduction capacity of the oil along the water flow path, followed by injection of nitrate, other nutrients (e.g., phosphate) and a consortium of NRB, if necessary. Hydrocarbon- and nitrate-mediated MEOR was tested in low- and high-pressure, water-wet sandpack bioreactors with 0.5 pore volumes of residual oil in place (ROIP). Compared to control bioreactors, those with 11-12 mM of toluene in the oil (gained by direct addition or by aqueous injection) and 80 mM of nitrate in the aqueous phase produced 16.5 ± 4.4% of additional ROIP (N = 10). Because toluene is a cheap commodity chemical, HN-MEOR has the potential to be a cost-effective method for additional oil production even in the current low oil price environment.
authors.affiliation: Petroleum Microbiology Research Group, Department of Biological Sciences, University of Calgary , 2500 University Dr. NW, Calgary, Alberta T2N 1N4, Canada.
authors.forename: Fatma
authors.initials: F
authors.lastname: Gassara
authors.affiliation: Petroleum Microbiology Research Group, Department of Biological Sciences, University of Calgary , 2500 University Dr. NW, Calgary, Alberta T2N 1N4, Canada.
authors.forename: Navreet
authors.initials: N
authors.lastname: Suri
authors.affiliation: Petroleum Microbiology Research Group, Department of Biological Sciences, University of Calgary , 2500 University Dr. NW, Calgary, Alberta T2N 1N4, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Stanislav
authors.affiliation: Petroleum Microbiology Research Group, Department of Biological Sciences, University of Calgary , 2500 University Dr. NW, Calgary, Alberta T2N 1N4, Canada.
authors.forename: Gerrit
authors.initials: G
authors.lastname: Voordouw
mesh_terms: D001419:Bacteria; D019149:Bioreactors / Q000382:microbiology; D000067071:Hydraulic Fracking / Q000379:methods*; D006838:Hydrocarbons; D009566:Nitrates; D010578:Petroleum / Q000382:microbiology; D014050:Toluene; D014867:Water
chemical_list: D006838:Hydrocarbons; D009566:Nitrates; D010578:Petroleum; D014867:Water; D014050:Toluene