The STIMTEC experiment at the Reiche Zeche ULab

To better understand constraints on bacteria at extremely low temperatures in ice, we describe here the adaptation of methods previously developed for sea ice to high magnification imaging of bacteria within fluid inclusions of Arctic lake ice under insitu conditions. Bacterial staining procedures, using the DNA-specific fluorescent stain DAPI, epifluorescence microscopy and image analysis were applied to lake-ice sections at in situ temperature (-5°C). Abundances of total, attached, free-living and metabolically active lake-ice bacteria were also determined from samples melted at 0°C using the fluorescent stains DAPI and CTC. Initial results indicate that, compared to sea ice at the same in situ temperature, lake ice contains fewer and more isolated liquid inclusions, limiting transport of fluids and motion of bacteria. Metabolically active cells were found in all ice samples (0.1 to 2.0% of the total counts), but on average less than in sea ice. Up to 50% of the total bacterial community were found to be associated with particles > 3 μm in size; of the metabolically active cells, a smaller fraction may be attached than in sea ice. Our results expand the spectrum of information available on bacteria in ice on a scale relevant to the organism and provide insight into characteristics of frozen microbial habitats on Earth and perhaps elsewhere in the Universe.

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Site Characterization for Field Radionuclide Migration Studies in Climax Granite

MRS Proceedings ◽

10.1557/proc-6-199 ◽

1981 ◽

Vol 6 ◽

Author(s):

Dana Isherwood ◽

Ellen Raber ◽

Randolph Stone

Keyword(s):

Flow Model ◽

Test Site ◽

Hydraulic Testing ◽

Nevada Test Site ◽

Radionuclide Migration ◽

Critical Question ◽

Initial Field ◽

In Situ Conditions ◽

Fracture Apertures

ABSTRACTRadionuclide migration experiments in fractured granite at the Climax Stock, Nevada Test Site, are needed to compare field and laboratory measured retardation factors to determine whether laboratory studies accurately reflect in situ conditions. Initial field activities have concentrated on hydrological investigations to determine whether the fractures in Climax granite are suitable for migration experiments. A critical question was whether we could isolate a single vertical fracture between two boreholes and establish flow along that fracture from an upper to a lower borehole. Of the ten fractures tested, one fracture would not take water at pressures up to 200 psig for 24 hours. Several fractures were so permeable they accepted water at a rate which exceeded the pumping capacity of the equipment. Other fractures failed to show a connection between the two boreholes. In two fractures, we were able to establish a circulating system with up to 95 percent of the injected water being recovered. Constant pressure injection tests were conducted. Intrinsic permeabilities of 33 and 75 (μm)2 were estimated using a radial nonsteady flow model. These values correspond to effective fracture apertures of 20 and 30 μm respectively. Concurrent with the hydraulic testing activities is a study of the Climax ground-water chemistry. Our analyses show the natural water to be very different in composition from the granite equilibrated water used in laboratory sorption studies. This paper includes the results of the hydrogeological and geochemical investigations, and describes the overall experimental design plans for the radionuclide migration experiments.

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Characterising induced acoustic emission activity observed during a mine-scale hydraulic-fracturing experiment in anisotropic crystalline rock

10.5194/egusphere-egu2020-9681 ◽

2020 ◽

Author(s):

Carolin Boese ◽

Grzegorz Kwiatek ◽

Georg Dresen ◽

Joerg Renner ◽

Thomas Fischer ◽

...

Keyword(s):

Acoustic Emission ◽

Focal Mechanism ◽

Crystalline Rock ◽

P Wave ◽

Principal Stresses ◽

Injection Point ◽

Hydraulic Stimulation ◽

Focal Mechanism Solutions ◽

In Situ Conditions ◽

Vertical Borehole

Between early 2018 and late 2019 the STIMTEC hydraulic stimulation experiment was performed at ca.~130 m below surface at the Reiche Zeche research mine in Freiberg, Saxony/Germany. The project aims at gaining insight into the creation and growth of fractures in anisotropic and heterogeneous crystalline rock units, to develop and optimise hydraulic stimulation techniques for EGS applications and to control the associated induced seismicity under in situ conditions. A series of ten hydro-frac experiments were performed in a 63 m-long, 15&#176;-inclined injection borehole and five mini-fracs for stress measurements in a sub-vertical borehole. These were monitored using a seismic monitoring system of twelve high-sensitivity Acoustic emission (AE) sensors, three accelerometers and one broadband sensor. More than 11,000 high-frequency AE events with source sizes on the cm-to-dm scale accompanied the hydraulic stimulation in five of ten stimulated intervals in the injection borehole. Several hundred AE events were recorded during the mini-fracs in the vertical borehole. We investigate the characteristics of induced AE events by combining information obtained from high-accuracy event locations using a transversely isotropic P-wave velocity model per station with station corrections, relative hypocentre locations, and focal mechanism solutions of selected events. The AE event clouds extend ca. 5 m radially from the injection points and show variying orientations and dips. The ca. 150 focal mechanism solutions obtained using P-wave polarisations display mixed-mode failure with a significant portion of them showing compaction. The orientation of the maximum principal stress inferred from the hydro-fracs in the injection and vertical boreholes has a trend of N348&#176;E and a plunge of 20&#176;, as typical for southeast Germany. However, discrepancies in the magnitudes of the principal stresses were measured between these boreholes ca. 15 m apart, resulting in different faulting regimes. We present stress orientations obtained from inverting focal mechanism solutions to provide additional information for interpreting stress-characterisation measurements.

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Evolution and hybridization in the radiolarian genera Theocorythium and Lamprocyclas

Paleobiology ◽

10.1017/s0094837300007818 ◽

1983 ◽

Vol 9 (4) ◽

pp. 341-354 ◽

Cited By ~ 15

Author(s):

Colin Baker

Keyword(s):

Morphological Change ◽

Genetic Information ◽

Phylogenetic Analyses ◽

Morphological Variability ◽

Single Species ◽

Core Material ◽

Evolutionary Models ◽

Insight Into ◽

Hybridization And Introgression

Changes in morphological variability within fossil populations of planktonic protists provide insight into the processes responsible for morphological change. Evolution in the radiolarian genera Theocorythium and Lamprocyclas is documented biometrically in Pliocene and Pleistocene core material from the equatorial Pacific and Indian Oceans. The patterns of morphological change in Theocorythium within a single Pacific core could be interpreted as indicating the in situ evolution of T. trachelium trachelium from T. vetulum via intermediate forms during the Pleistocene. However, consideration of biogeographic data shows that this is not the case and supports instead two alternate interpretations: (1) immigration coupled with extensive hybridization and introgression, or (2) multiple polymorphs of a single species changing in frequency along a cline. Analyses of evolutionary change in Theocorythium and the closely related genus Lamprocyclas during the Pliocene suggest that hybridization may be a significant factor in the production of new species. Evolutionary models and phylogenetic analyses should consider that barriers to gene flow may vary significantly with time and permit the exchange of genetic information between populations previously reproductively isolated.

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The Radlonuclide Migration Experiment at the Grimsel Rock Laboratory, Switzerland

MRS Proceedings ◽

10.1557/proc-112-179 ◽

1987 ◽

Vol 112 ◽

Author(s):

Ian G. McKinley ◽

W. Russell Alexander ◽

Claudine Bajo ◽

Urs Frick ◽

Jörg Hadermann ◽

...

Keyword(s):

Safety Assessment ◽

Crystalline Rock ◽

Radionuclide Migration ◽

Support Programme ◽

Rock Laboratory ◽

First Results ◽

Migration Experiment ◽

Site Characterisation

AbstractThis paper describes the programme for an in-situ radionuclide migration experiment in fractured crystalline rock and presents the first results of site characterisation work. This study is particularly notable for its extensive hydrologic/geochemical support programme and the use of radiotracers identified as important in safety assessment studies.

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Importance of fracture deformation throughout hydraulic testing under in-situ conditions

Geophysical Journal International ◽

10.1093/gji/ggab354 ◽

2021 ◽

Author(s):

P Schmidt ◽

N Dutler ◽

H Steeb

Keyword(s):

Inverse Analysis ◽

Fractured Reservoirs ◽

Experimental Studies ◽

Measurement Data ◽

Hydraulic Testing ◽

Fractured Reservoir ◽

Fracture Deformation ◽

In Situ Conditions ◽

Flow Processes

Summary In this work, we propose a hydro-mechanical simulation model to study the strong interaction of fluid flow and fracture deformation under in-situ stress conditions. The general model is reduced under physics-based assumptions to provide an efficient numerical approach for inverse analysis of experimental studies and is applied to experimental field data obtained from hydraulic tests conducted at the Grimsel Test Site (GTS), Switzerland. The present set of hydro-mechanical measurement data provides not only valuable information about the transient pressure and flow evolution but also the transient change of fracture deformation. We aim to introduce a strongly-coupled hydro-mechanical model to numerically characterize the fractured reservoir based on experimental data below the limit of hydraulically induced irreversible changes of the reservoir’s properties. Insights into the leading mechanisms of flow processes throughout hydraulic testing under in-situ conditions are then gained by best numerical fits of the measurement data. Based on the experimental and numerical findings, this study emphasizes the importance of a consistent consideration of local and non-local fracture deformation throughout inverse analysis of hydraulic testing data to a) better understand hydro-mechanical flow processes in fractured reservoirs and b), to increase the estimation quality of hydraulic properties of tested fractures.

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Experimental study of shale drillability with different bedding inclinations under varying wellbore pressure conditions

Journal of Petroleum Exploration and Production Technology ◽

10.1007/s13202-021-01140-2 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1751-1759

Author(s):

Shuai Chen ◽

Xiangchao Shi ◽

Heng Bao ◽

Leiyu Gao ◽

Jie Wu

Keyword(s):

Mechanical Properties ◽

Shale Gas ◽

Physical And Mechanical Properties ◽

In Situ Conditions ◽

Wellbore Pressure ◽

Development Engineering ◽

The Impact ◽

The Relationship ◽

Insight Into

AbstractIn the practice of shale gas development engineering, it is important to understand the physical and mechanical properties of shale. The bedding inclinations of shale are known to significantly influence its physical and mechanical properties. This study mainly examined the influence of bedding inclinations on drillability under different wellbore pressures. The bedding inclinations used in this study varied from 0° to 90°, with a gradient of 15°. The wellbore pressure values used varied from 0 to 25 MPa, with a gradient of 5 MPa. The results show that the drillability index of shale increases exponentially with increasing wellbore pressure at different bedding inclinations. The proposed exponential empirical model can describe the relationship between the drillability index and wellbore pressure. When the wellbore pressure is less than 15 MPa, bedding inclinations significantly influence the drillability index, and the drillability index of shale shows a “W”-type variation trend as the bedding inclinations increase in the range of 0° to 90°. The influence of bedding inclinations on drillability decreases gradually with increasing wellbore pressure. When the wellbore pressure increases to 25 MPa, the impact of bedding inclinations on drillability is virtually undetectable. The results of this study can provide reasonably insight into the effect of bedding inclinations on shale deformation under the drill bit, and useful prediction for the drillability index under in situ conditions.

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FIRST RESULTS OF ASEISMIC FAULT SLIP AND LEAKAGE PRECEDING AN EARTHQUAKE INDUCED DURING AN IN SITU FAULT REACTIVATION EXPERIMENT IN SHALES (MONT TERRI FS EXPERIMENT, SWITZERLAND)

10.1130/abs/2016am-284136 ◽

2016 ◽

Author(s):

Yves Guglielmi ◽

◽

Louis de Barros ◽

Christophe Nussbaum ◽

Jens Birkholzer ◽

...

Keyword(s):

Fault Slip ◽

Fault Reactivation ◽

First Results ◽

Mont Terri

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Rock Surface Fungi in Deep Continental Biosphere—Exploration of Microbial Community Formation with Subsurface In Situ Biofilm Trap

Microorganisms ◽

10.3390/microorganisms9010064 ◽

2020 ◽

Vol 9 (1) ◽

pp. 64

Author(s):

Maija Nuppunen-Puputti ◽

Riikka Kietäväinen ◽

Lotta Purkamo ◽

Pauliina Rajala ◽

Merja Itävaara ◽

...

Keyword(s):

Significant Proportion ◽

Debaryomyces Hansenii ◽

Fungal Communities ◽

Fungal Colonization ◽

Rock Surface ◽

Mica Schist ◽

Deep Subsurface ◽

Bacterial Phyla ◽

In Situ Conditions

Fungi have an important role in nutrient cycling in most ecosystems on Earth, yet their ecology and functionality in deep continental subsurface remain unknown. Here, we report the first observations of active fungal colonization of mica schist in the deep continental biosphere and the ability of deep subsurface fungi to attach to rock surfaces under in situ conditions in groundwater at 500 and 967 m depth in Precambrian bedrock. We present an in situ subsurface biofilm trap, designed to reveal sessile microbial communities on rock surface in deep continental groundwater, using Outokumpu Deep Drill Hole, in eastern Finland, as a test site. The observed fungal phyla in Outokumpu subsurface were Basidiomycota, Ascomycota, and Mortierellomycota. In addition, significant proportion of the community represented unclassified Fungi. Sessile fungal communities on mica schist surfaces differed from the planktic fungal communities. The main bacterial phyla were Firmicutes, Proteobacteria, and Actinobacteriota. Biofilm formation on rock surfaces is a slow process and our results indicate that fungal and bacterial communities dominate the early surface attachment process, when pristine mineral surfaces are exposed to deep subsurface ecosystems. Various fungi showed statistically significant cross-kingdom correlation with both thiosulfate and sulfate reducing bacteria, e.g., SRB2 with fungi Debaryomyces hansenii.

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Development of Fragility Curves for Piping and Slope Stability of River Levees

Water ◽

10.3390/w13050738 ◽

2021 ◽

Vol 13 (5) ◽

pp. 738

Author(s):

Nicola Rossi ◽

Mario Bačić ◽

Meho Saša Kovačević ◽

Lovorka Librić

Keyword(s):

Slope Stability ◽

Fragility Curves ◽

Safety Margin ◽

Water Levels ◽

Flood Event ◽

Soil Parameters ◽

Design Code ◽

A Site ◽

Insight Into

The design code Eurocode 7 relies on semi-probabilistic calculation procedures, through utilization of the soil parameters obtained by in situ and laboratory tests, or by the means of transformation models. To reach a prescribed safety margin, the inherent soil parameter variability is accounted for through the application of partial factors to either soil parameters directly or to the resistance. However, considering several sources of geotechnical uncertainty, including the inherent soil variability, measurement error and transformation uncertainty, full probabilistic analyses should be implemented to directly consider the site-specific variability. This paper presents the procedure of developing fragility curves for levee slope stability and piping as failure mechanisms that lead to larger breaches, where a direct influence of the flood event intensity on the probability of failure is calculated. A range of fragility curve sets is presented, considering the variability of levee material properties and varying durations of the flood event, thus providing crucial insight into the vulnerability of the levee exposed to rising water levels. The procedure is applied to the River Drava levee, a site which has shown a continuous trend of increased water levels in recent years.

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