Mechanistic study of microbial control of hydrogen sulfide production in oil reservoirs

• Published in: Biotechnology and bioengineering 2001-09, Vol.74 (5), p.424-434
• Main Authors: Nemati, M., Jenneman, G. E., Voordouw, G.
• Format: Article
• Language: English
• Subjects: Applied sciences; Bacteria - metabolism; Biological and medical sciences; Biotechnology; Crude oil, natural gas and petroleum products; Crude oil, natural gas, oil shales producing equipements and methods; Desulfovibrio; Desulfovibrio - metabolism; Energy; Enhanced oil recovery methods; Exact sciences and technology; Fuel Oils - microbiology; Fuels; Fundamental and applied biological sciences. Psychology; hydrogen sulfide; Hydrogen Sulfide - metabolism; Industrial applications and implications. Economical aspects; nitrate; Nitrates - metabolism; oil reservoir; Oxidation-Reduction; Prospecting and production of crude oil, natural gas, oil shales and tar sands; reverse sample genome probing; Sodium Lactate - metabolism; souring; Sulfates - metabolism; Sulfides - metabolism; Thiobacillus - metabolism; Thiomicrospira; Thiomicrospira sp. strain CVO; Use of microorganisms or biopolymers in fossil fuel recovery; Water - metabolism
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/bit.1133

Microbial control of biogenic production of hydrogen sulfide in oil fields was studied in a model system consisting of pure cultures of the nitrate‐reducing, sulfide‐oxidizing bacterium (NR‐SOB) Thiomicrospira sp. strain CVO and the sulfate‐reducing bacterium (SRB) Desulfovibrio sp. strain Lac6, as well as in microbial cultures enriched from produced water of a Canadian oil reservoir. The presence of nitrate at concentrations up to 20 mM had little effect on the rate of sulfate reduction by a pure culture of Lac6. Addition of CVO imposed a strong inhibition effect on production of sulfide. In the absence of added nitrate SRB we were able to overcome this effect after an extended lag phase. Simultaneous addition of CVO and nitrate stopped the production of H2S immediately. The concentration of sulfide decreased to a negligible level due to nitrate‐dependent sulfide oxidation activity of CVO. This was not prevented by raising the concentration of Na‐lactate, the electron donor for sulfate reduction. Similar results were obtained with enrichment cultures. Enrichments of produced water with sulfide and nitrate were dominated by CVO, whereas enrichments with sulfate and Na‐lactate were dominated by SRB. Addition of an NR‐SOB enrichment to an SRB enrichment inhibited the production of sulfide. Subsequent addition of sufficient nitrate caused the sulfide concentration to drop to zero. A similar response was seen in the presence of nitrate alone, although after a pronounced lag time, it was needed for emergence of a sizable CVO population. The results of the present study show that two mechanisms are involved in microbial control of biogenic sulfide production. First, addition of NR‐SOB imposes an inhibition effect, possibly by increasing the environmental redox potential to levels which are inhibitory for SRB. Second, in the presence of sufficient nitrate, NR‐SOB oxidize sulfide, leading to its complete removal from the environment. Successful microbial control of H2S in an oil reservoir is crucially dependent on the simultaneous presence of NR‐SOB (either indigenous population or injected) and nitrate in the environment. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 74: 424–434, 2001.