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Microbial redox processes in deep subsurface environments and the potential application of (per)chlorate in oil reservoirs.

Liebensteiner MG, Tsesmetzis N, Stams AJ, Lomans BP - Front Microbiol (2014)

Bottom Line: Microbial reduction of (per)chlorate is a thermodynamically favorable redox process, also at high temperature.However, knowledge about (per)chlorate reduction at elevated temperatures is still scarce and restricted to members of the Firmicutes and the archaeon Archaeoglobus fulgidus.By analyzing the diversity and phylogenetic distribution of functional genes in (meta)genome databases and combining this knowledge with extrapolations to earlier-made physiological observations we speculate on the potential of (per)chlorate reduction in the subsurface and more precisely oil fields.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Microbiology, Wageningen University Wageningen, Netherlands.

ABSTRACT
The ability of microorganisms to thrive under oxygen-free conditions in subsurface environments relies on the enzymatic reduction of oxidized elements, such as sulfate, ferric iron, or CO2, coupled to the oxidation of inorganic or organic compounds. A broad phylogenetic and functional diversity of microorganisms from subsurface environments has been described using isolation-based and advanced molecular ecological techniques. The physiological groups reviewed here comprise iron-, manganese-, and nitrate-reducing microorganisms. In the context of recent findings also the potential of chlorate and perchlorate [jointly termed (per)chlorate] reduction in oil reservoirs will be discussed. Special attention is given to elevated temperatures that are predominant in the deep subsurface. Microbial reduction of (per)chlorate is a thermodynamically favorable redox process, also at high temperature. However, knowledge about (per)chlorate reduction at elevated temperatures is still scarce and restricted to members of the Firmicutes and the archaeon Archaeoglobus fulgidus. By analyzing the diversity and phylogenetic distribution of functional genes in (meta)genome databases and combining this knowledge with extrapolations to earlier-made physiological observations we speculate on the potential of (per)chlorate reduction in the subsurface and more precisely oil fields. In addition, the application of (per)chlorate for bioremediation, souring control, and microbial enhanced oil recovery are addressed.

No MeSH data available.


Related in: MedlinePlus

Schematic representation of water flood with nitrate injection in cold, and hot oil reservoirs with heterogeneous and homogeneous permeability distribution. The difference in the thermal gradient (graph) and the size of the injection/formation water mixing zone (dark blue) determine zones that are dominated by nitrate- (NRP, blue), mesophilic and (hyper)thermophilic SRP (m-SRP, red and t-SRP, yellow, respectively). Hyperthermophilic nitrate-reducing microorganism like e.g., Pyrobaculum aerophilum have not yet been identified in significant numbers in samples derived from oil reservoirs. Nitrate injection does provide protection against souring in the vicinity of the injector well bore in hot reservoirs (right panel), but this protection becomes significantly more challenging in the deeper nitrate-depleted parts of the low-temperature reservoir exposed to sulfate-containing injection or formation water (left panel). Reservoir souring is also strongly dependent on the mixing of nutrients from the formation and injection water and therefore tends to be more extensive in heterogeneous reservoirs (middle panel).
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Figure 3: Schematic representation of water flood with nitrate injection in cold, and hot oil reservoirs with heterogeneous and homogeneous permeability distribution. The difference in the thermal gradient (graph) and the size of the injection/formation water mixing zone (dark blue) determine zones that are dominated by nitrate- (NRP, blue), mesophilic and (hyper)thermophilic SRP (m-SRP, red and t-SRP, yellow, respectively). Hyperthermophilic nitrate-reducing microorganism like e.g., Pyrobaculum aerophilum have not yet been identified in significant numbers in samples derived from oil reservoirs. Nitrate injection does provide protection against souring in the vicinity of the injector well bore in hot reservoirs (right panel), but this protection becomes significantly more challenging in the deeper nitrate-depleted parts of the low-temperature reservoir exposed to sulfate-containing injection or formation water (left panel). Reservoir souring is also strongly dependent on the mixing of nutrients from the formation and injection water and therefore tends to be more extensive in heterogeneous reservoirs (middle panel).

Mentions: Reservoir souring had long been considered to occur only due to abiotic subsurface processes (Herbert, 1987; Eden et al., 1993; Khatib and Salanitro, 1997). When the role of sulfate-reducing bacteria was acknowledged (Ligthelm et al., 1991; Sunde et al., 1993), this resulted in efforts directed to develop strategies to mitigate microbial reservoir souring. So far, this has resulted in a number of proposed strategies: nitrate injection, sulfate removal and biocide injection. Although probably most effective in the majority of cases, sulfate removal is only scarcely applied for souring mitigation purposes. This is due to the high investment and operational cost associated with sulfate removal units. Application of biocide is used by oil and gas companies to achieve microbial control in their surface production and processing facilities, but it is generally debated whether it is effective to control reservoir souring as its effect does not extend sufficiently deep into the reservoir formations. Nitrate injection is the most widely accepted and used strategy to control microbial reservoir souring, especially effective in hot reservoirs with homogeneous permeability distribution (Figure 3; right panel) and to a somewhat lower extend also in ones with a highly heterogeneous permeability distribution (Figure 3; middle panel). Nitrate is considered to be effective in controlling reservoir souring by; (1) the competitive exclusion of sulfate-reducing bacteria by more efficient nitrate-reducing bacteria (competing over the same electron donating compounds; volatile fatty acids, BTEX, other hydrocarbons, etc.), (2) inhibition of the dissimilatory sulfite reductase, a key enzyme in the sulfate reduction pathway, by nitrite (an intermediate in reduction of nitrate; Wolfe et al., 1994), and (3) the oxidation of generated sulfide by nitrate-reducing sulfide-oxidizing bacteria (Hubert and Voordouw, 2007). The effectiveness of nitrate injection to control souring is, however, questionable for low-temperature reservoirs. Nitrate might provide protection against souring in the vicinity of the injector well bore, but not in the deeper nitrate-depleted parts of the low-temperature reservoir exposed to injection water containing 30–60 times more sulfate than nitrate (Callbeck et al., 2011, 2013). This would result in the development of zones that are dominated either by nitrate- and sulfate-reducing communities (Figure 3; left panel; Voordouw et al., 2009). The success of nitrate injection to control souring in low temperature reservoirs is therefore very much linked to how deep nitrate can be delivered into the reservoir.


Microbial redox processes in deep subsurface environments and the potential application of (per)chlorate in oil reservoirs.

Liebensteiner MG, Tsesmetzis N, Stams AJ, Lomans BP - Front Microbiol (2014)

Schematic representation of water flood with nitrate injection in cold, and hot oil reservoirs with heterogeneous and homogeneous permeability distribution. The difference in the thermal gradient (graph) and the size of the injection/formation water mixing zone (dark blue) determine zones that are dominated by nitrate- (NRP, blue), mesophilic and (hyper)thermophilic SRP (m-SRP, red and t-SRP, yellow, respectively). Hyperthermophilic nitrate-reducing microorganism like e.g., Pyrobaculum aerophilum have not yet been identified in significant numbers in samples derived from oil reservoirs. Nitrate injection does provide protection against souring in the vicinity of the injector well bore in hot reservoirs (right panel), but this protection becomes significantly more challenging in the deeper nitrate-depleted parts of the low-temperature reservoir exposed to sulfate-containing injection or formation water (left panel). Reservoir souring is also strongly dependent on the mixing of nutrients from the formation and injection water and therefore tends to be more extensive in heterogeneous reservoirs (middle panel).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4150442&req=5

Figure 3: Schematic representation of water flood with nitrate injection in cold, and hot oil reservoirs with heterogeneous and homogeneous permeability distribution. The difference in the thermal gradient (graph) and the size of the injection/formation water mixing zone (dark blue) determine zones that are dominated by nitrate- (NRP, blue), mesophilic and (hyper)thermophilic SRP (m-SRP, red and t-SRP, yellow, respectively). Hyperthermophilic nitrate-reducing microorganism like e.g., Pyrobaculum aerophilum have not yet been identified in significant numbers in samples derived from oil reservoirs. Nitrate injection does provide protection against souring in the vicinity of the injector well bore in hot reservoirs (right panel), but this protection becomes significantly more challenging in the deeper nitrate-depleted parts of the low-temperature reservoir exposed to sulfate-containing injection or formation water (left panel). Reservoir souring is also strongly dependent on the mixing of nutrients from the formation and injection water and therefore tends to be more extensive in heterogeneous reservoirs (middle panel).
Mentions: Reservoir souring had long been considered to occur only due to abiotic subsurface processes (Herbert, 1987; Eden et al., 1993; Khatib and Salanitro, 1997). When the role of sulfate-reducing bacteria was acknowledged (Ligthelm et al., 1991; Sunde et al., 1993), this resulted in efforts directed to develop strategies to mitigate microbial reservoir souring. So far, this has resulted in a number of proposed strategies: nitrate injection, sulfate removal and biocide injection. Although probably most effective in the majority of cases, sulfate removal is only scarcely applied for souring mitigation purposes. This is due to the high investment and operational cost associated with sulfate removal units. Application of biocide is used by oil and gas companies to achieve microbial control in their surface production and processing facilities, but it is generally debated whether it is effective to control reservoir souring as its effect does not extend sufficiently deep into the reservoir formations. Nitrate injection is the most widely accepted and used strategy to control microbial reservoir souring, especially effective in hot reservoirs with homogeneous permeability distribution (Figure 3; right panel) and to a somewhat lower extend also in ones with a highly heterogeneous permeability distribution (Figure 3; middle panel). Nitrate is considered to be effective in controlling reservoir souring by; (1) the competitive exclusion of sulfate-reducing bacteria by more efficient nitrate-reducing bacteria (competing over the same electron donating compounds; volatile fatty acids, BTEX, other hydrocarbons, etc.), (2) inhibition of the dissimilatory sulfite reductase, a key enzyme in the sulfate reduction pathway, by nitrite (an intermediate in reduction of nitrate; Wolfe et al., 1994), and (3) the oxidation of generated sulfide by nitrate-reducing sulfide-oxidizing bacteria (Hubert and Voordouw, 2007). The effectiveness of nitrate injection to control souring is, however, questionable for low-temperature reservoirs. Nitrate might provide protection against souring in the vicinity of the injector well bore, but not in the deeper nitrate-depleted parts of the low-temperature reservoir exposed to injection water containing 30–60 times more sulfate than nitrate (Callbeck et al., 2011, 2013). This would result in the development of zones that are dominated either by nitrate- and sulfate-reducing communities (Figure 3; left panel; Voordouw et al., 2009). The success of nitrate injection to control souring in low temperature reservoirs is therefore very much linked to how deep nitrate can be delivered into the reservoir.

Bottom Line: Microbial reduction of (per)chlorate is a thermodynamically favorable redox process, also at high temperature.However, knowledge about (per)chlorate reduction at elevated temperatures is still scarce and restricted to members of the Firmicutes and the archaeon Archaeoglobus fulgidus.By analyzing the diversity and phylogenetic distribution of functional genes in (meta)genome databases and combining this knowledge with extrapolations to earlier-made physiological observations we speculate on the potential of (per)chlorate reduction in the subsurface and more precisely oil fields.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Microbiology, Wageningen University Wageningen, Netherlands.

ABSTRACT
The ability of microorganisms to thrive under oxygen-free conditions in subsurface environments relies on the enzymatic reduction of oxidized elements, such as sulfate, ferric iron, or CO2, coupled to the oxidation of inorganic or organic compounds. A broad phylogenetic and functional diversity of microorganisms from subsurface environments has been described using isolation-based and advanced molecular ecological techniques. The physiological groups reviewed here comprise iron-, manganese-, and nitrate-reducing microorganisms. In the context of recent findings also the potential of chlorate and perchlorate [jointly termed (per)chlorate] reduction in oil reservoirs will be discussed. Special attention is given to elevated temperatures that are predominant in the deep subsurface. Microbial reduction of (per)chlorate is a thermodynamically favorable redox process, also at high temperature. However, knowledge about (per)chlorate reduction at elevated temperatures is still scarce and restricted to members of the Firmicutes and the archaeon Archaeoglobus fulgidus. By analyzing the diversity and phylogenetic distribution of functional genes in (meta)genome databases and combining this knowledge with extrapolations to earlier-made physiological observations we speculate on the potential of (per)chlorate reduction in the subsurface and more precisely oil fields. In addition, the application of (per)chlorate for bioremediation, souring control, and microbial enhanced oil recovery are addressed.

No MeSH data available.


Related in: MedlinePlus