Microbial formation and degradation of hydrocarbons - Research in the area of energy resources

Country / Region: supra-regional

Begin of project: January 1, 2004

End of project: December 31, 2020

Status of project: April 28, 2016

• Results 2004 – 2016
• Outlook

The microbial formation and degradation of hydrocarbons are studied with focus on the biotechnological conversion and production of energy resources. The main objectives are the microbial formation of methane in oil and coal reservoirs (Geomicrobiology) and also the oxidation of methane. Another main objective is the investigation of the hydrocarbon degradation potentials of microbial communities in Arctic sediments. Microbial investigations linked to the potential utilization of the geological subsurface (geothermal energy, gas storage) are another topic of our studies.

Sampling of deepsea sediments with a multicorer - Cruise Panorama-2 Barentssea Source: BGR

To a large extent Germany is dependent on the import of energy resources. Consequently, research in this field is of great importance. Nevertheless, even under optimal conditions, today not more than 30-40 % of the total oil in a reservoir are actually recovered. The majority remains in a polyphasic mixture with exploration water in the reservoir. Since almost 20 years it is known from stable isotope studies that large amounts of biogenic methane are formed in oil reservoirs. This microbial degradation of oil to methane is independent from external electron acceptors, and only needs water and small amounts of nutrients and trace elements. Consequently, this methanogenesis is a suitable model to explain oil biodegradation and gas formation in reservoirs, without the availability of oxygen, nitrate or sulfate as oxidants. The investigation of this degradation process and of the underlying biogeochemical controls are of great economical and social importance due to several reasons: (1) The understanding of reservoir biodegradation is of great use for the exploration industry, (2) a biotechnological stimulation of the methane formation in reservoirs could provide new economical perspectives, (3) the use of microorganisms to enhance oil recovery (MEOR) has proven to be successful. The conversion of at least parts of this non-recoverable oil via an appropriate biotechnological treatment into easily recoverable methane would provide an extensive and ecologically sound energy resource.

High pressure reactor for the investigation of microbial hydrocarbon degradation under Arctic deepsea conditions Source: BGR

Results 2004 – 2016

About 7 % of the annual global methane emissions originate from coal mining. The results obtained so far show that microbially produced methane contributes significantly to the controlled and uncontrolled methane emissions in the Ruhr Basin. Dependent on the sites between 38 to 90 % of this methane originates from microbial production (Thielemann et al. 2004). A change in the isotopic composition of the methane at some sites points towards a recent microbial methane formation. Another objective in this context was the determination of the contribution of recently formed microbial methane in gas, oil and coal reservoirs, and the investigation of the involved microorganisms. This should allow reliable predictions concerning a potential economic use of this process.

Similar observation are made worldwide in oil reservoirs. In microbiological research projects currently investigations are carried out to determine the living conditions of the methane producing organisms detected in coal and oil reservoirs, and to quantify gas formation rates. Furthermore, in two DFG-financed projects the microbial processes and microorganisms were studied, to allow a better prediction of the degree of degradation of selected reservoirs to aid exploration industries.

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Outlook

The anaerobic microbial degradation of hydrocarbons to methane in deep oil reservoirs has, besides its scientific, also great economic and social importance, due to the deterioration of the oil quality. Therefore, samples from different geological systems (like oil, gas, shale and gas reservoirs, mud volcanoes, marine sediments) are studied concerning the involved microbial processes and organisms, and for a better characterization of alike reservoirs. Further it will be studied, if and if yes how these or other indigenous microorganisms or their metabolic traits, like acid, gas, surfactant or biofilm formation, could be stimulated in situ in oil reservoirs to increase the recovery of fossil energy resources (MEOR).

Sampling campaign in closed mines in the Ruhr District Source: BGR

A new focus of research in the AB Geomicrobiology lies on the hydrocarbon-related microbiology of northern frontier areas (Project PANORAMA). Currently, uncertainties exist concerning potential environmental consequences in context with ongoing commercial development of the Arctic. Consequently it is necessary to study the hydrocarbon-degrading microbial populations in the different sedimentary ecosystems in the northern frontier areas, their environmental characteristics, as well as potential hydrocarbon degradation rates in the laboratory under close to in situ conditions. This research topic contributes to a better assessment of potential riscs and the development of sustainable measures for exploration.

Literature:

• Gründger F., Jiménez N., Thielemann T., Straaten N., Lüders T., Richnow H.-H., Krüger M. (2015): Microbial methane formation in deep aquifers of a coal-bearing sedimentary basin, Germany. Front. Microbiol.6: 1-14
• Schulz H.-M., Biermann S., van Berk W., Krüger M., Straaten N., Bechtel A., Wirth R., Lüders V., Schovsbo N.H., Crabtree S. (2015): From shale oil to biogenic shale gas: Retracing organic– inorganic interactions in the Alum Shale (Furongian–Lower Ordovician) in southern Sweden. AAPG Bulletin 99: 927-956.
• Krüger M., van Berk W., Arning E.T., Jiménez N., Schovsbo N.H., Straaten N., Schulz H.-M. (2014): The biogenic methane potential of European gas shale analogues: Results from incubation experiments and thermodynamic modeling. International Journal of Coal Geology 136: 59–74.
• Siegert M., Taubert M., von Bergen M., Seifert J., Bastida F., Richnow H.-H., Krüger M. (2013): Nitrate reduction and nitrogen assimilation is linked to sulfate reduction and heterotrophy in anaerobic methanotrophic mats of the Black Sea. FEMS Microbiol. Ecol. 86: 231-245.
• Algora C., Gründger F., Adrian L., Damm V., Richnow H.-H., Krüger M. (2013): Geochemistry and microbiology of Arctic marine sediments from the Northern Baffin Bay. Geomicrobiol. J. 30: 690-705.
• Jimenez N., Morris B.E.M., Gründger F., Cai M., Richnow H.-H., Yao J., Krüger M. (2012): Evidence for in situ methanogenic oil degradation in the Dagang oil field. Org.Geochem. 52: 44-54.
• Siegert M., Krüger M., Teichert B., Schippers A. (2011): Anaerobic oxidation of methane dominates hydrocarbon degradation at a marine methane seep in the Sumatra forearc basin, Indian Ocean. Front. Microbiol. 2: 1-16.
• Beckmann S., Krüger M., Engelen B., Gorbushina A., Cypionka H. (2011): Role of Bacteria, Archaea and Fungi involved in methane release in abandoned coal mines. Geomicrobiol. J. 28: 347-358.
• Siegert, M., Cichoka, D., Feisthauer, S., Richnow, H.-H., Gründger, F., Springael, D., Krüger, M. (2011): Accelerated methanogenesis from aliphatic and aromatic hydrocarbons under iron and sulfate reducing conditions. FEMS Microbiol. Lett. 315: 6-16.
• Feisthauer, S., Siegert, M., Seidel, M., Richnow, H.-H., Zengler, K., Krüger, M. (2010): Isotope fingerprints of methane and CO2 for exploring methane formation from aliphatic and aromatic hydrocarbons. Org. Geochem. 41: 482-490.
• Krüger, M., Beckmann, S., Engelen, B., Thielemann, T., Cramer, B., Schippers, A., Cypionka, H. (2009): Microbial methane formation from hard coal and timber in an abandoned coal mine. Geomicrobiol. J. 25: 315-321.
• Thielemann, Th., B. Cramer, and A. Schippers. (2004): Coalbed methane in the Ruhr basin, Germany: A renewable energy resource? Org. Geochem. 35: 1537-1549.