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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 oil displacement in a petroleum reservoir. Ideal matrix piston-wise (stable) displacement leaving low residual oil levels (A) with the close-up showing the residual oil (black blobs) attached to sand grain particles (brown), unstable displacement showing fingering of water into the oil phase (B), unstable displacement due to thief zones (C) and unstable displacement through fractures (especially for carbonates; D). Oil phase is indicated in black, water in blue. Small black blobs indicated residual oil after being flooded, small blue blobs indicate connate water before being flooded.
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Figure 4: Schematic representation of oil displacement in a petroleum reservoir. Ideal matrix piston-wise (stable) displacement leaving low residual oil levels (A) with the close-up showing the residual oil (black blobs) attached to sand grain particles (brown), unstable displacement showing fingering of water into the oil phase (B), unstable displacement due to thief zones (C) and unstable displacement through fractures (especially for carbonates; D). Oil phase is indicated in black, water in blue. Small black blobs indicated residual oil after being flooded, small blue blobs indicate connate water before being flooded.

Mentions: The efficiency of oil recovery from oil reservoirs is very often limited due to the geological structure of the oil-bearing formation and the oil characteristics. Although a matrix, piston-wise displacement of the target oil is intended (Figure 4A), the actual displacement is often highly unstable due to fingering of water in oil (because of viscosity differences; Figure 4B) or preferred flow through high permeable zones (Figure 4C) or fractures (Figure 4D). MEOR has already been proposed at the advent of modern oil production (Beckman, 1926). Although several MEOR trials have been reported and hundreds of patents are filed, the process often lacks reproducibility or remains unproven (Brown, 2010; Bachmann et al., 2014). Moreover, most of the MEOR trials are in fact well stimulation rather than “full-field” MEOR treatments. Many driving mechanisms for MEOR were postulated, of which the in situ generation of biosurfactant received lots of attention. Convincing evidence that in situ microbes will be able to generate sufficient amounts of effective surfactant in a full-field setting in order to increase the capillary number sufficiently such that residual oil is indeed mobilized is, however, still lacking. A critical analysis of the proposed mechanistic drivers for MEOR revealed that only the plugging of high-permeability zones (aka conformance control), seemed to be most plausible (Gray et al., 2008). In order to be feasible for a field-wide application, an MEOR process based on conformance control would have to rely on the stimulation of indigenous microbes (avoiding requirement of injecting microbes) utilizing part of the hydrocarbon fraction (or in situ commonly occurring volatile fatty acids) as electron donor. The reduction of (per)chlorate in the subsurface might liberate highly oxidative chlorine intermediates or even oxygen in a de facto anaerobic environment. Reactive chlorine oxyanions (chlorite) and oxygen may either chemically or biologically oxidize (in)organic compounds (e.g., sulfide, ferrous iron, hydrocarbons etc.) in the vicinity of the (per)chlorate reducer. The availability of oxygen is also a crucial pre-requisite for hydrocarbon-utilizing mono- and dioxygenases. These may yield “activated hydrocarbons” that are subsequently more easily degradable by (other) microorganisms. The presence of oxygen would enable facultative prokaryotes to switch from a lower-efficiency anaerobic “lifestyle” to a more efficient microaerophilic metabolism, generating more biomass. We therefore propose that injection of (per)chlorate alone or in combination of nitrate and phosphates (if the latter proves to be limiting), might be able to sufficiently stimulate the indigenous microbial community to achieve conformance control and thereby enhance oil production. Further research is needed to show the effectiveness of (per)chlorate injection for MEOR.


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 oil displacement in a petroleum reservoir. Ideal matrix piston-wise (stable) displacement leaving low residual oil levels (A) with the close-up showing the residual oil (black blobs) attached to sand grain particles (brown), unstable displacement showing fingering of water into the oil phase (B), unstable displacement due to thief zones (C) and unstable displacement through fractures (especially for carbonates; D). Oil phase is indicated in black, water in blue. Small black blobs indicated residual oil after being flooded, small blue blobs indicate connate water before being flooded.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: Schematic representation of oil displacement in a petroleum reservoir. Ideal matrix piston-wise (stable) displacement leaving low residual oil levels (A) with the close-up showing the residual oil (black blobs) attached to sand grain particles (brown), unstable displacement showing fingering of water into the oil phase (B), unstable displacement due to thief zones (C) and unstable displacement through fractures (especially for carbonates; D). Oil phase is indicated in black, water in blue. Small black blobs indicated residual oil after being flooded, small blue blobs indicate connate water before being flooded.
Mentions: The efficiency of oil recovery from oil reservoirs is very often limited due to the geological structure of the oil-bearing formation and the oil characteristics. Although a matrix, piston-wise displacement of the target oil is intended (Figure 4A), the actual displacement is often highly unstable due to fingering of water in oil (because of viscosity differences; Figure 4B) or preferred flow through high permeable zones (Figure 4C) or fractures (Figure 4D). MEOR has already been proposed at the advent of modern oil production (Beckman, 1926). Although several MEOR trials have been reported and hundreds of patents are filed, the process often lacks reproducibility or remains unproven (Brown, 2010; Bachmann et al., 2014). Moreover, most of the MEOR trials are in fact well stimulation rather than “full-field” MEOR treatments. Many driving mechanisms for MEOR were postulated, of which the in situ generation of biosurfactant received lots of attention. Convincing evidence that in situ microbes will be able to generate sufficient amounts of effective surfactant in a full-field setting in order to increase the capillary number sufficiently such that residual oil is indeed mobilized is, however, still lacking. A critical analysis of the proposed mechanistic drivers for MEOR revealed that only the plugging of high-permeability zones (aka conformance control), seemed to be most plausible (Gray et al., 2008). In order to be feasible for a field-wide application, an MEOR process based on conformance control would have to rely on the stimulation of indigenous microbes (avoiding requirement of injecting microbes) utilizing part of the hydrocarbon fraction (or in situ commonly occurring volatile fatty acids) as electron donor. The reduction of (per)chlorate in the subsurface might liberate highly oxidative chlorine intermediates or even oxygen in a de facto anaerobic environment. Reactive chlorine oxyanions (chlorite) and oxygen may either chemically or biologically oxidize (in)organic compounds (e.g., sulfide, ferrous iron, hydrocarbons etc.) in the vicinity of the (per)chlorate reducer. The availability of oxygen is also a crucial pre-requisite for hydrocarbon-utilizing mono- and dioxygenases. These may yield “activated hydrocarbons” that are subsequently more easily degradable by (other) microorganisms. The presence of oxygen would enable facultative prokaryotes to switch from a lower-efficiency anaerobic “lifestyle” to a more efficient microaerophilic metabolism, generating more biomass. We therefore propose that injection of (per)chlorate alone or in combination of nitrate and phosphates (if the latter proves to be limiting), might be able to sufficiently stimulate the indigenous microbial community to achieve conformance control and thereby enhance oil production. Further research is needed to show the effectiveness of (per)chlorate injection for MEOR.

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