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Neubrandenburg, Germany

Westphal A.,German Research Center for Geosciences | Lerm S.,German Research Center for Geosciences | Miethling-Graff R.,German Research Center for Geosciences | Seibt A.,BWG Geochemische Beratung GmbH | And 3 more authors.
Applied Microbiology and Biotechnology

The microbial biocenosis in highly saline fluids produced from the cold well of a deep geothermal heat store located in the North German Basin was characterized during regular plant operation and immediately after plant downtime phases. Genetic fingerprinting revealed the dominance of sulfate-reducing bacteria (SRB) and fermentative Halanaerobiaceae during regular plant operation, whereas after shutdown phases, sequences of sulfur-oxidizing bacteria (SOB) were also detected. The detection of SOB indicated oxygen ingress into the well during the downtime phase. High 16S ribosomal RNA (rRNA) and dsrA gene copy numbers at the beginning of the restart process showed an enrichment of bacteria, SRB, and SOB during stagnant conditions consistent with higher concentrations of dissolved organic carbon (DOC), sulfate, and hydrogen sulfide in the produced fluids. The interaction of SRB and SOB during plant downtimes might have enhanced the corrosion processes occurring in the well. It was shown that scale content of fluids was significantly increased after stagnant phases. Moreover, the sulfur isotopic signature of the mineral scales indicated microbial influence on scale formation. © 2015 Springer-Verlag Berlin Heidelberg Source

Luschen E.,Leibniz Institute for Applied Geophysics | Wolfgramm M.,Geothermie Neubrandenburg GmbH GTN | Fritzer T.,Bavarian Environment Agency LFU | Dussel M.,Leibniz Institute for Applied Geophysics | And 2 more authors.

A 3D seismic survey was undertaken as part of a research project to characterize the Upper Jurassic (Malm) hydrothermal reservoir at the geothermal power plant at Unterhaching, Munich, and to simulate its potential for sustainable usage. A suite of promising geothermal targets could be identified on this relatively small survey size of 27km2, where several geothermal projects are expected to potentially influence each other. Among these targets are fault patterns of high complexity with en-echelon elements, circular structures, dolomitized reefs and mounds, reduced seismic velocities which indicate brittle disaggregation, and preferential orientations of joints and fissures. © 2013 Elsevier Ltd. Source

Alawi M.,Helmholtz Center Potsdam | Lerm S.,Helmholtz Center Potsdam | Vetter A.,Helmholtz Center Potsdam | Wolfgramm M.,Geothermie Neubrandenburg GmbH GTN | And 2 more authors.

Enhanced process understanding of engineered geothermal systems is a prerequisite to optimize plant reliability and economy. We investigated microbial, geochemical and mineralogical aspects of a geothermal groundwater system located in the Molasse Basin by fluid analysis. Fluids are characterized by temperatures ranging from 61°C to 103°C, salinities from 600 to 900 mg/l and a dissolved organic carbon content (DOC) between 6.4 to 19.3 mg C/l. The microbial population of fluid samples was analyzed by genetic fingerprinting techniques based on PCR-amplified 16S rRNA- and dissimilatory sulfite reductase genes. Despite of the high temperatures, microbes were detected in all investigated fluids. Fingerprinting and DNA sequencing enabled a correlation to metabolic classes and biogeochemical processes. The analysis revealed a broad diversity of sulfate-reducing bacteria. Overall, the detection of microbes known to be involved in biocorrosion and mineral precipitation indicates that microorganisms could play an important role for the understanding of processes in engineered geothermal systems. © 2011 Springer-Verlag. Source

Zimmermann J.,TU Bergakademie Freiberg | Franz M.,TU Bergakademie Freiberg | Wolfgramm M.,Geothermie Neubrandenburg GmbH GTN
Neues Jahrbuch fur Geologie und Palaontologie - Abhandlungen

The Late Aalenian (earliest Middle Jurassic) Polyplocussandstein Formation in the vicinity of Wolfsburg (SE Lower Saxony, Germany) was deposited on the progradational lower delta plain of a large fluvial-dominated delta system. Detailed lithofacies analyses on several outcrops point to five associations of eight lithofacies types: i) point bar sheets, ii) chute channels, iii) natural levees, iv) crevasse splay sheet sandstones and v) interdistributary bays and, combined with published well data, enable a more detailed palaeogeographic reconstruction than previously available. Palaeohydraulic analysis on lateral shifting point bar sheets of a subsidiary distributary channel enable the reconstruction of an up to 45 m wide and 4 m deep meandering channel of high sinuosity (P 1.8) and mean transport direction towards 298. The meander belt was at maximum 350 m wide (Wm) and characterised by an annual discharge of up to 17 m/s (Qm) and mean flood discharge of up to 210 m/s (Qma). Discharge varied only slightly between stages of bankfull and low depth but resulted locally in crevassing of natural levees and formation of crevasse splays. Crevasse splays were transported towards northwestern and northeastern direction and are characterised by tabular sand sheets of aggradational architecture. Their propagation is indicated by downstream accreting cross-bedded bedforms and their termination by down-current directed thinning and rapid facies transitions to clayey lithologies of interdistributary bays. However, dark clays of interdistributary bays are slightly enriched in organic carbon but redox indices (Ni/Co, U/Th) indicate deposition under oxic conditions.©2014 E. Schweizerbartsche Verlagsbuchhandlung, Stuttgart, Germany. Source

Lerm S.,Helmholtz Center Potsdam | Westphal A.,Helmholtz Center Potsdam | Miethling-Graff R.,Helmholtz Center Potsdam | Alawi M.,Helmholtz Center Potsdam | And 3 more authors.

The microbial diversity of a deep saline aquifer used for geothermal heat storage in the North German Basin was investigated. Genetic fingerprinting analyses revealed distinct microbial communities in fluids produced from the cold and warm side of the aquifer. Direct cell counting and quantification of 16S rRNA genes and dissimilatory sulfite reductase (dsrA) genes by real-time PCR proved different population sizes in fluids, showing higher abundance of bacteria and sulfate reducing bacteria (SRB) in cold fluids compared with warm fluids. The operation-dependent temperature increase at the warm well probably enhanced organic matter availability, favoring the growth of fermentative bacteria and SRB in the topside facility after the reduction of fluid temperature. In the cold well, SRB predominated and probably accounted for corrosion damage to the submersible well pump and iron sulfide precipitates in the near wellbore area and topside facility filters. This corresponded to lower sulfate content in fluids produced from the cold well as well as higher content of hydrogen gas that was probably released from corrosion, and maybe favored growth of hydrogenotrophic SRB. This study reflects the high influence of microbial populations for geothermal plant operation, because microbiologically induced precipitative and corrosive processes adversely affect plant reliability. © 2013 Springer Japan. Source

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