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Obtaining accurate porosity information of fluvial sediment deposits is helpful and desirable for many tasks of river engineers. Besides direct measurements of single samples and empirical formulas specialized for specific cases, packing models promise efficient predictions due to their theoretical and extensible foundation. The objective of this work is thus to investigate the usability of three such models in order to obtain a suitable porosity prediction method for the challenging case of fluvial sediment packing. There, the complexity originates from wide continuous size distributions, from silt to gravel, and different grain shapes. We use data obtained from extensive numerical packing simulations to determine the required model parameters and to verify the models' accuracy for moderate size ratios. This study reveals systematic deficits in one of the models, which can be attributed to the absence of a built-in mixture packing model. By combining these findings with data from laboratory measurements and extending the model to include cohesive effects, we exemplify that reasonable porosity predictions can be obtained with the Compressible Packing Model for the Rhine river in Germany. Through an additional comparison with data from French rivers, guidelines for a successful prediction in cases with limited prior knowledge of the model parameters are developed. Future model enhancements of the packing models directly, and by incorporating more effects that are known to influence porosity, are expected to improve the predictive performance. [ABSTRACT FROM AUTHOR]

The effects of the double and the multiple application (2 to 6) of Calosil® (IBZ-Salzchemie GmbH, Halsbruecke, Germany) E25, IP 25 and E50 products were studied on Maastricht limestone, which is characterized by high porosity and large pores. Both destructive and non-destructive laboratory tests we performed in order to assess the consolidating efficiency of the nanolimes—the bending and compressive strengths, ultrasound velocity measurement, porosity determination and SEM examination. Except for the compressive strength, the other characteristics were investigated in the depth profile of stone specimens to find the distribution of the treatment product within the substrate. The performed tests showed good penetration of CaLoSiL nanolime products into the studied limestone. The bending strengths of limestone samples after double treatment using nanolime E 25, IP25 and E 50 were found to be increased by 50%, 44% and 89%, respectively, whereas the compressive strength increased by 50%, 23% and 73%. The porosity of the stone was reduced by the treatment, but only slightly, to an acceptable extent. The higher sum of performed nanolime applications resulted in a higher strengthening effect but at the same time at the uneven distribution of the product in the stone specimen, which was followed by an increase in the strength and decrease of open porosity in the surface part. SEM examination showed a modification of the stone microstructure by the added binder. [ABSTRACT FROM AUTHOR]

Tight carbonate rocks are important hydrocarbon and potential geothermal reservoirs, for example, in CO2-Enhanced Geothermal Systems. We report a study of outcrop samples of tectonically undeformed tight carbonates from the upper Jurassic "Malm ß" formation in Southern Germany near the town of Simmelsdorf (38 km NE of Nuremberg) to understand bulk petrophysical properties in relation to microstructure and to compare models for permeability prediction in these samples. We applied Archimedes isopropanol immersion, Helium pycnometry, mercury injection, gamma density core logging, and gas permeability measurements, combined with microstructural investigations and liquid metal injection (LMI-BIB-SEM). In addition, ultrasonic velocity was measured to allow geomechanical comparison of stratigraphically equivalent rocks in the South German Molasse Basin (SGMB). Results show only small variations, showing that the formation is rather homogeneous with bulk porosities below 5% and argon permeabilities around 1.4E−17 m2. The presence of stylolites in some of the samples has neither a significant effect on porosity nor permeability. Pores are of submicron size with pore throats around 10 nm and connected as shown by Mercury injection and Liquid Metal injection. Samples have high dynamic Young's Modulus of 73 ± 5 GPa as expected for lithified and diagenetically overmature limestones. Moreover, no trends in properties were observable toward the faults at meter scale, suggesting that faulting was post-diagenetic and that the matrix permeabilities were too low for intensive post-diagenetic fluid–rock interaction. Petrophysical properties are very close to those measured in the SGMB, illustrating the widespread homogeneity of these rocks and justifying the quarry as a reasonable reservoir analog. Permeability prediction models, such as the percolation theory-based Katz-Thompson Model, Poiseuille-based models, like the Winland, the Dastidar, the capillary tube, and the Kozeny-Carman Models, as well as several empirical models, namely, the Bohnsack, the Saki, and the GPPT Models, were applied. It is shown that the capillary tube Model and the Saki Model are best suited for permeability predictions from BIB-SEM and mercury injection capillary pressure results, respectively, providing a method to estimate permeability in the subsurface from drill cuttings. Matrix permeability is primarily controlled by the pore (throat) diameters rather than by the effective porosity. [ABSTRACT FROM AUTHOR]

Fractures in subsurface lithologies globally host economically significant energy resources and can be preferential fluid migration pathways. With the naturally fractured Upper Carboniferous sandstones of the Ruhr Basin located within Germany’s most densely populated area, the utilisation for powering one of Europe’s largest district heating infrastructure can be an option. Since the Upper Carboniferous sandstone matrix exhibits poor reservoir quality (average porosity: 8%, permeability: up to 3 mD), fractures are believed to primarily control fluid flow. By combining data from two outcrops (exposing the Namurian C and Westphalian A) with a wellbore data set (penetrating the Westphalian A), this study aims to develop a refined understanding of the fracture network. The present-day stress control on hydraulically conductive fracture orientations is studied by performing critically stressed fracture analysis for three different SHmax orientation scenarios. Kaisberg (Namurian C) and Finefrau (Westphalian A) Sandstone outcrops show three dominant fracture trends: NNW– SSE to N–S, NNE–SSW to NE–SW and WNW–ESE. The characterised fracture networks of both outcrops follow a top-bounded height distribution pattern, with fractures being mostly bed restricted. Therefore, bed thickness is identified as a controlling factor limiting fracture height. Based on 600 m of oriented core material from the Upper Carboniferous strata (Bork 10 wellbore), the analysis of the in-situ fracture network revealed two dominant fracture orientations: N–S and W–E. Fracture intensity indicates a varying degree of fracturing of the drilled sandstone layers for both trends (N–S: 0 to 9.1 m-1, W–E: 0 to 8.8 m-1). Comparison of dipmeter log fracture interpretations with reliable core description data shows a poor match (11%) for depth location (± 6 m) and dip azimuth (± 25°). Slip tendency analysis highlighted near-vertical N–S and NW–SE striking fractures to be generally favourably oriented for reactivation within the active stress field. In total, 10% of the detected fracture population (Bork 10 wellbore) are critically stressed under present-day stress conditions and may contribute to large scale fluid flow in the subsurface. [ABSTRACT FROM AUTHOR]

The Molasse Basin is one of the most promising areas for deep geothermal exploitation in Germany and the target horizon is the aquifer in the Upper Jurassic carbonates. Carbonate deposits can be very heterogeneous even over a small area due to diagenetic processes and varying depositional environments. The preferential targets for geothermal exploitation in carbonate deposits are fault zones, reef facies and karstified areas, since they are expected to act as hydraulically permeable zones due to high porosity and high permeability. Therefore, identifying these structures and characterizing, e.g., their internal porosity distribution are of high importance. This can be accomplished using 3D reflection seismic data. Besides structural information, 3D seismic surveys provide important reservoir properties, such as acoustic impedance, from which a porosity model can be derived. In our study area in Munich we carried out a seismic amplitude inversion to get an acoustic impedance model of the Upper Jurassic carbonate reservoir using a 3D seismic data set, a corresponding structural geological model, and logging data from six wells at the 'Schäftlarnstraße' geothermal site. The impedance model and porosity logs were than used to calculate a porosity model. The model shows a wide porosity range from 0 to 20% for the entire reservoir zone and the lithology along the wells reveals that dolomitic limestone has the highest porosities and calcareous dolomite has the lowest porosities. The study area is cut by a large W–E striking fault, the Munich Fault, and the footwall north of it shows higher porosities and more intense karstification than the hanging wall to the south. Considering the entire study area, an increase in porosity from east to west is observed. Furthermore, we identified a complex porosity distribution in reef buildups and pinnacle reefs. The reef cores have mostly low porosities of, e.g., < 3% and the highest porosities of up to 7 to 14% are observed at the reef caps and on the reef slopes. The reef slopes show a characteristic interfingering of the reef facies with the surrounding bedded facies, which indicates a syn-sedimentary reef development with slightly varying build up growth rates. We also assessed the reservoir quality with regard to porosity distribution and determined areas with moderate to good quality for geothermal exploitation by defining porosity evaluation levels. The porosity evaluation maps show that the carbonate rocks of Berriasian to Malm ζ 1 are preferential targets for exploitation, especially in the footwall of the Munich Fault and to the west of the hanging wall, because these areas are characterized by high porosities due to intense karstification of bedded and massive facies, although the latter is mainly restricted to reef caps and reef slopes. [ABSTRACT FROM AUTHOR]

Porosity changes in the near-surface area of sandstones due to long-term weathering can produce deterioration. Therefore, porosity analyses on weathered sandstones are significant for detecting possible influences on the pore structure. Classical methods for determining the porosity and pore size distribution in sandstones can only investigate the entire sample volume. In contrast, in this publication, the porosity was analysed in 0.2 mm steps over a depth of 5 mm by means of single-sided NMR measurements on water-saturated sandstones under vacuum. Evaluations of Obernkirchener and Schleeriether Sandstones that were weathered outdoors in Germany for over 30 years are presented. The results showed that the water content in Vol.-% strongly correlated with the normalised NMR signal. The unweathered sandstones showed a uniform distribution of micro and capillary pores throughout the stone depth. As a result of 30 years of outdoor weathering, changes in the pore structure occurred at the sandstone surface due to weathering down to depths of about 0.6 mm. The porosity of the Schleeriether Sandstone samples, mainly the microporosity, clearly increased in this region. Due to the dominance of capillary pores in the Obernkirchener Sandstone, the changes were not as pronounced, but a shift towards smaller pores in the surface area was observable. [ABSTRACT FROM AUTHOR]

Radish concretions exhibit a typical columnar to pear‐shaped, stipe downward geometry. In Middle Jurassic mudrock in south‐west Germany, radish concretions started to form around an iron‐sulphide lined tube by pervasive cementation constituting an ellipsoidal parent domain in uncompacted sediment at burial depths of ≤5 to 8 m as recorded by 75 to 80% minus‐cement porosity. Thereafter, the concretions grew vertically in compacting sediment as evidenced by laminae within the concretions being increasingly inclined towards the tips, and concomitantly decreasing minus‐cement porosity. During early diagenesis, prior to septarian crack formation, bicarbonate generating the microbial cement originated within the sulphate reduction zone chiefly from anaerobic oxidation of methane and to a lesser degree of organoclastic material. Later, at 50 to 70 m burial depth, septarian cracks formed as evaluated by sedimentation–compaction analysis based on minus‐cement porosity data and compressibility of similarly composed sediments. The outward‐narrowing septarian cracks indicate that they formed when the concretions were still in a plastic state but already cemented sufficiently to be resistant against compaction. In this stage, up to one‐quarter of the pore volume of the concretions was still open as suggested by shrinkage experiments. This pore volume, and the septarian cracks, were filled with cement termed late diagenetic. In the study area, the decompacted net‐sedimentation rate was low, about 2 to 3 cm kyr−1, for ca 2.5 Myr, allowing the concretions to reside for a long time within the sulphate reduction zone and to grow. Radish concretions formed within the transition zone from thick, rapidly deposited to long‐term, slowly accumulating sediment. [ABSTRACT FROM AUTHOR]

The lateral heterogeneity of reservoir rocks is important to assess storage potential and permeability. This case study focusses on a Lower Triassic (upper Olenekian) outcrop of fluvial sandstones of the Plattensandstein Member (Röt Formation) near Röttbach in the southern part of the Germanic Basin, Central southern Germany. The Buntsandstein Group is considered a suitable reservoir for thermal storage or exploration in Central southern Germany. In the Röttbach Quarry, the >10 m thick lithic arkoses are exposed over 35 m laterally in three adjacent walls and consist of two units separated by an erosive surface. They are covered by several metres of the Lower Röt Claystone Member. Using sedimentological logging, spectral gamma ray-, porosity- and permeability measurements as well as petrographic analyses calculating compaction parameters, lateral reservoir quality differences are studied. Sedimentary structures in the multi-storey channels suggest a point bar deposit. The migration direction of the channels correlates with deteriorating reservoir quality. This reduction in porosity and permeability correlates with an increased detrital mica and authigenic illite content, the occurrence of rip-up clasts and a lateral increase of gamma ray signatures by 19 API (avg. 5.0 vol% K, 2.7 ppm U, 11.9 ppm Th). The occurrence of larger amounts of mica and clay minerals is linked to decreasing flow velocities throughout the evolution of a meandering system. They enhance compaction and reduce available intergranular pore space. Permeability laterally deteriorates by up to three orders of magnitude (48 to 0.02 mD, avg. 9 mD) while measured porosities show minor variability (11 to 19%, avg. 16%). The deterioration of reservoir quality is related to compactional (COPL 11 to 28%, avg. 18%) and cementational porosity loss (CEPL 13 to 29%, avg. 22%) and is mainly controlled by detrital mica and authigenic illite. [ABSTRACT FROM AUTHOR]

In geothermal reservoir systems, changes in pore pressure due to production (depletion), injection or temperature changes result in a displacement of the effective stresses acting on the rock matrix of the aquifer. To compensate for these intrinsic stress changes, the rock matrix is subjected to poroelastic deformation through changes in rock and pore volume. This in turn may induce changes in the effective pore network and thus in the hydraulic properties of the aquifer. Therefore, for the conception of precise reservoir models and for long-term simulations, stress sensitivity of porosity and permeability is required for parametrization. Stress sensitivity was measured in hydrostatic compression tests on 14 samples of rock cores stemming from two boreholes of the Upper Jurassic Malm aquifer of the Bavarian Molasse Basin. To account for the heterogeneity of this carbonate sequence, typical rock and facies types representing the productive zones within the thermal reservoir were used. Prior to hydrostatic investigations, the hydraulic (effective porosity, permeability) and geomechanical (rock strength, dynamic, and static moduli) parameters as well as the microstructure (pore and pore throat size) of each rock sample were studied for thorough sample characterization. Subsequently, the samples were tested in a triaxial test setup with effective stresses of up to 28 MPa (hydrostatic) to simulate in-situ stress conditions for depths up to 2000 m. It was shown that stress sensitivity of the porosity was comparably low, resulting in a relative reduction of 0.7–2.1% at maximum effective stress. In contrast, relative permeability losses were observed in the range of 17.3–56.7% compared to the initial permeability at low effective stresses. Stress sensitivity coefficients for porosity and permeability were derived for characterization of each sample and the different rock types. For the stress sensitivity of porosity, a negative correlation with rock strength and a positive correlation with initial porosity was observed. The stress sensitivity of permeability is probably controlled by more complex processes than that of porosity, where the latter is mainly controlled by the compressibility of the pore space. It may depend more on the compaction of precedented flow paths and the geometry of pores and pore throats controlling the connectivity within the rock matrix. In general, limestone samples showed a higher stress sensitivity than dolomitic limestone or dolostones, because dolomitization of the rock matrix may lead to an increasing stiffness of the rock. Furthermore, the stress sensitivity is related to the history of burial diagenesis, during which changes in the pore network (dissolution, precipitation, and replacement of minerals and cements) as well as compaction and microcrack formation may occur. This study, in addition to improving the quality of input parameters for hydraulic–mechanical modeling, shows that hydraulic properties in flow zones largely characterized by less stiff, porous limestones can deteriorate significantly with increasing effective stress. [ABSTRACT FROM AUTHOR]

• Suevite used to build the church is weaker when wet, thought to be due to its high clay content. • Water-weakening could explain the weathering susceptibility of the original suevite. • Physical properties of replacement sandstone differ from the original suevite building stone. • Physical properties of replacement suevite closely match those of the original suevite building stone. • We recommended that the church be restored using natural suevite. An asteroid impact in southwest Germany ca. 15 Ma left a > 20 km-diameter blanket of poorly sorted clastic rock, called suevite. In the 15th century, the suevite was used to construct a Gothic church (St. George's church, Nördlingen). Visual inspection of the church highlights its strong weathering susceptibility. We investigate whether the suevite used to construct the church and the rocks used in its restoration (suevite and sandstone) are weaker when saturated with water, important for conservation strategies. We additionally assess, by comparing their physical properties, the suitability of the replacement stones. We show that the strength of the suevite used to build the church is reduced by half when water-saturated, considered here a consequence of its high smectite content. This helps explain the prevalent weathering of the stones forming the outer walls of the church. The replacement suevite has a higher wet/dry strength ratio than the original suevite and is therefore more resistant to weathering. Not only does the replacement sandstone have a low ratio of wet/dry strength, but also its physical properties are different from the original suevite, which has almost identical physical properties to those of the replacement suevite. Based on these results, and the appearance of the stones, we recommend that, where possible, natural suevite stones be used to replace the weathered blocks of suevite at St. George's church and at buildings built using suevite within the region. [ABSTRACT FROM AUTHOR]

Mudstones are regarded as potential host rocks for nuclear waste storage in several countries. In Germany, Jurassic and Lower Cretaceous mudstones have been identified as potential targets. These formations experienced vastly different subsidence and uplift as well as temperature and pressure histories, taking influence on petrophysical, geochemical and geomechanical properties. This study investigates burial and erosion history of these mudstones in Northern Germany and the resultant changes of important physical properties: porosity, permeability, thermal conductivity using numerical basin and temperature history modelling. 1D models provide detailed site specific information taking local stratigraphy and lithology into account, while 3D models need some simplification, but provide large scale information and allow investigating lateral fluid migration and thermal effects. The southern and central part of the study area is the Lower Saxony Basin, where Lower Cretaceous and Jurassic mudstones were buried deeply and were later uplifted and - in parts of the area - eroded. Therefore, physical properties are not related to present-day depth. In contrast, further to the north in the area of the Pompeckj Block, physical properties are closely related to present-day depth. Lowest porosities and permeabilities are calculated for Liassic and Doggerian mudstones in the southwest close to the border of the states Lower Saxony and North Rhine-Westphalia, which were affected by strong burial followed by major uplift. More information is needed on thickness and facies variability of mudstones and direct measurements on their porosities and permeabilities at different stages of burial. Obtaining such data is, however, much more difficult than for sandstones or carbonates. In addition, geomechanical properties will strongly depend on maximum burial depth, temperature and pressure history which needs to be investigated in detail. [ABSTRACT FROM AUTHOR]

We present a multi-scale 3D analysis of the pore network in a Rotliegend reservoir sandstone, both at the scale of the sand grains and the scale of the diagenetic clay cements that grow in the intragranular volume (IGV). For this we combine optical microscopy, micro-CT, Broad Ion Beam polishing, Scanning Electron Microscopy, Woods Metal Porosimetry and Focussed Ion Beam–SEM tomography. In cm-scale layers the samples show differences in IGV and sand fabric. In the layers where IGV is higher, there is less diagenetic cement and the IGV forms a connected network; in the layers where the sand fabric is more compacted, larger pores are connected via the pore network in the diagenetic clay cements with pore throat size down to 20 nm in diameter. We show that the pore network in all types of diagenetic clay is connected and conclude that the total gas volume that can be produced from such a reservoir sandstone includes the pore volume in the diagenetic clay cements. We predict a major change in transport properties when the diagenetic clay fill renders the IGV disconnected. [ABSTRACT FROM AUTHOR]

After decades of hydrocarbon exploration and production in the Lower Triassic Buntsandstein from the Central European Basin center, the marginal southern German Buntsandstein has gained interest as a potential lithology for geothermal applications and lithium brine extractions. For this purpose and in order to better understand reservoir quality, porosity and permeability in combination with point-counted petrographic data of sandstones from SW Germany covering the Lower, Middle, and Upper Buntsandstein are studied. Textural, mineralogical, and petrophysical data show that the eolian and fluvial sandstones represent a heterogeneous reservoir system. Permeabilities vary over six orders of magnitude from 0.001 to 515 mD, while porosities are in the range of 7.9–21.5%. Different controls on reservoir quality exist. Large grain sizes ≥0.31 mm together with total quartz contents are the major controls on reservoir quality. Additional controls on reservoir quality are exerted by authigenic phases. Since porosity loss is dominated by compaction, the influence of authigenic clay phases on reservoir quality is minor. However, illite coatings on detrital quartz efficiently inhibited syntaxial quartz overgrowth. Where illite coatings lack, syntaxial quartz overgrowths locally stabilized the granular framework and, thus, preserved primary porosity. These authigenic phases, however, represent a local control, which cannot be applied on a regional scale. Similarly, enhanced secondary porosity due to feldspar dissolution is locally restricted and minor. The comparison with other studies on the Buntsandstein shows that its reservoir system is highly heterogeneous over small and large scales and within the same stratigraphic levels. In this study, quartz-rich and authigenic clay-poor sandstones with relative large grain sizes interpreted as eolian deposits reveal the best reservoir qualities. • Combined measured porosity and permeability, and point-counted petrographic data. • Reservoir quality of one of the main geothermal reservoirs in south Germany. • Besides minor controls, large grain size is the main control on reservoir quality. • Interacting authigenic cements represent local/minor controls on reservoir quality. • Buntsandstein is a heterogeneous reservoir system on spatial & stratigraphic scales. [ABSTRACT FROM AUTHOR]

Underground land use can play a significant role in future concepts of energy and gas storage and requires an improved understanding of the parameters of potential storage formations (saline aquifers), for instance of porosity and permeability, and also of mineralogical and gas compositions. This study aims at providing data examples and calculating vertical spatial variations through variogram analyses of important North German geological reservoirs from Dogger, Rhaetian, Middle Buntsandstein, and Rotliegend (Sub)Groups and Formations, focusing on the western part of the North German Basin. Vertical correlation lengths of porosity and permeability data range between 0 and 30 m, while most results are calculated at approximately 2-4 m and do not show relevant differences among the evaluated formations. In the majority of the regarded formations, the Kozeny-Carman relationship between porosity and permeability is supported as long as low porosity and permeability values are excluded from the evaluation. Mineral percentages varied significantly among the evaluated sediments. Besides quartz, ankerite is the main compound in the Dogger Group, while feldspars and clay minerals were more frequent in the Rhaetian, Middle Buntsandstein, and Rotliegend sediments. Methane was the main gas compound in the reservoirs, followed by nitrogen, ethane, and carbon dioxide. This study serves as preparatory work to allow for the parameterization of geological models and a subsequent simulation of fluid transport to evaluate (long-term) safety and impacts of geothermal and gas storage projects. [ABSTRACT FROM AUTHOR]

Abstract: Exploration of unconventional gas resources from Paleozoic formations in northwestern Germany is just getting started. Large, potential gas reservoirs are presumed to be present north of the Rhenish Massif, where Mississippian and Pennsylvanian marine black shales occur. This paper comprises geochemical and mineralogical data and other important aspects of potentially economic black shale formations of the Carboniferous. Additionally, the burial and thermal history was reconstructed using 1D modeling software (Schlumberger). These 1D models were calibrated with vitrinite reflectance data from outcrops and shallow wells. In general, all Paleozoic black shales are at present highly mature, between about 1.5 and >3% vitrinite reflectance. The shales of the uppermost Mississippian (Upper Alum Shale/Chokier Formation) have high contents of organic carbon, are tens of meters thick and can be regarded as potential gas shale targets. Most other Mississippian and Pennsylvanian black shales are relatively thin. Adjacent carbonates are often stained black and rich in solid bitumen, indicating former oil impregnation of these reservoirs. [Copyright &y& Elsevier]

Abstract: This contribution reports on the study of the pore space morphology in two early mature (VRr =0.59 and 0.61) samples of Posidonia Shale from the Hils Syncline in Germany, using Broad Ion Beam (BIB) polishing and high resolution Scanning Electron Microscopy (SEM). This allows imaging pores with resolution down to 10nm in equivalent diameter (deq), and quantitative estimation of porosity. Using a combination of BSE and SE detectors and semi-automatic segmentation of the gigapixel images, the representative elementary area of the samples, on the scale of a few mm, is inferred to be about 140×140μm2. Pore morphologies and pore sizes are clearly related to the mineral fabric, with large differences: very large (typically several microns) pores with internal faceted crystal morphology in recrystallized calcite clasts, and smaller pores (deq <1024nm) in clay-rich matrix and in cf. Schizosphaerella nanofossils (typically 200nm). Pores are less common in organic material and in pyrite aggregates. Pore characteristics are very similar for both samples, and porosity resolvable by BIB-SEM is 2.75 and 2.74%. Pore size distribution can be described by a power-law, with an exponent about 2.0 and 2.2, respectively, for the pore population excluding the fossils. Pores in the carbonate fossils show dual-power-law distribution with power-law exponents of about 1 and 3. By extrapolating the power-law distribution for each sample, total porosity is estimated to be 4.8% (−0.9, +1.7%), and 6.5% (−2.7, +7.2%), respectively. This estimate can be compared with 3.4–3.7 and 3.3–3.6% as measured by mercury injection porosimetry. We interpret this difference to reflect the unconnected (for mercury) part of the porosity. Comparison of imaged pores and mercury injection porosimetry suggest a very high pore body to pore throat ratio. This results in a pore model where large pores, represented mainly by pores in fossils and calcite grains, are connected via a low-porous (and low-permeable) clay-rich matrix with pore throats below 10nm in both samples. [Copyright &y& Elsevier]

In the framework of the German R&D joint project CLEAN (CO large-scale enhanced gas recovery in the Altmark natural gas field), Rotliegend reservoir sandstones of the Altensalzwedel block in the Altmark area (Saxony-Anhalt, central Germany) have been studied to characterise litho- and diagenetic facies, mineral content, geochemical composition, and petrophysical properties. These sands have been deposited in a playa environment dominated by aeolian dunes, dry to wet sand flats and fluvial channel fills. The sediments exhibit distinct mineralogical, geochemical, and petrophysical features related to litho- and diagenetic facies types. In sandstones of the damp to wet sandflats, their pristine red colours are preserved and porosity and permeability are only low. Rocks of the aeolian environment and most of the channel fill deposits are preferentially bleached and exhibit moderate to high porosity and permeability. Although geochemical element whole rock content in these rocks is very similar, element correlations are different. Variations in porosity and permeability are mainly due to calcite and anhydrite dissolution and differences in clay coatings with Fe-bearing illitic-chloritic composition exposed to the pore space. Moreover, mineral dissolution patterns as well as compositions (of clays and carbonate) and morphotypes of authigenic minerals (chlorite, illite) are different in red and bleached rocks. Comparison of the geochemical composition and mineralogical features of diagenetically altered sandstones and samples exposed to CO-bearing fluids in laboratory batch experiments exhibit similar character. Experiments prove an increase in wettability and water binding capacity during CO impact. [ABSTRACT FROM AUTHOR]

Abstract: Vertical Electrical Sounding (VES) data are used to estimate the porosity and the hydraulic conductivity of the Ruhrtal aquifer in western Germany in addition to mapping the aquifer therein. Two theoretical methods based respectively on Kozeny–Archie equations and Ohm''s–Darcy''s laws are used for better confidence level in estimated values from VES data. Estimated hydraulic conductivity values from VES data and those determined from pumping test are strongly correlated. [Copyright &y& Elsevier]

An important component of any CO2 sequestration project is seismic monitoring for tracking changes in subsurface physical properties, such as velocity and density. Different reservoirs have different amplitude variation with offset (AVO) responses, which can define underground conditions. In the present paper we investigate walkaway vertical seismic profile (VSP) AVO response to CO2 injection at the Ketzin site, the first European onshore CO2 sequestration pilot study dealing with research on geological storage of CO2. First, we performed rock physics analysis to evaluate the effect of injected CO2 on seismic velocity using the Biot-Gassmann equation. On the basis of this model, the seismic response for different CO2 injection saturation was studied using ray tracing modeling. We then created synthetic walkaway VSP data, which we then processed. In contrast, synthetic seismic traces were created from borehole data. Finally, we found that the amplitude of CO2 injected sand layer with different gas saturations were increased with the offset when compared with the original brine target layer. This is the typical class III AVO anomaly for gas sand layer. The AVO responses matched the synthetic seismic traces very well. Therefore, walkaway VSP AVO response can monitor CO2 distribution in the Ketzin area. [ABSTRACT FROM AUTHOR]

Using data from 6 full-scale municipal membrane bioreactors (MBR) in Germany the hydraulic capacity utilisation and specific energy consumption were studied and their connexion shown. The average hydraulic capacity utilisation lies between 14% and 45%. These low values are justified by the necessity to deal with intense rain events and cater for future flow increases. However, this low hydraulic capacity utilisation leads to high specific energy consumption. The optimisation of MBR operation requires a better utilisation of MBR hydraulic capacity, particularly under consideration of the energy-intensive membrane aeration. A first approach to respond to large influent flow fluctuations consists in adjusting the number of operating modules. This is practised by most MBR operators but so far mostly with variable flux and constant membrane aeration. A second approach is the real-time adjustment of membrane aeration in line with flux variations. This adjustment is not permitted under current manufacturers' warranty conditions. A further opportunity is a discontinuous operation, in which filtration takes place over short periods at high flux and energy for membrane aeration is saved during filtration pauses. The integration of a buffer volume is thereby indispensable. Overall a modular design with small units, which can be activated/ inactivated according to the influent flow and always operate under optimum conditions, enables a better utilisation of MBR hydraulic capacity and forms a solid base to reduce MBR energy demand. [ABSTRACT FROM AUTHOR]

Abstract: CCS is discussed in a broad sense throughout Europe. In this paper a cautious, conservative estimate of CO2 storage capacity for Germany and its neighboring countries where CO2 emissions from Germany could possibly be stored (Netherlands, France, Denmark, Norway, UK and Poland) is presented. Such a lower limit calculation is necessary for orientation purposes for potential investors and political decision-makers. Conservative CO2 sequestration capacity in deep saline aquifers for Germany is derived by the volumetric approach where parameters such as efficiency factor, CO2 density, porosity of the geological formation are of interest. It is assumed that every geological system is closed and thus an efficiency factor of 0.1 per cent (based on maximum pressure increase and total compressibility) for saline aquifers is applied. The capacity of German depleted oil and gas fields is based on cumulative recovery data and a sweep efficiency of 75 percent. The storage capacity in the other considered countries, adjacent to Germany, are based on a critical review and adjustment of the results of the European reports JOULE II, GESTCO and GeoCapacity. The conservative capacities for all countries together amount to 49 Gt CO2, from which Norway and the UK provide 36 Gt, all offshore in the North Sea. Compared to the emissions from large point sources in these countries during 40 years (47.6 Gt of CO2), a virtual balance is achieved. This can only be reached, if a large scale CO2 pipeline system is installed to connect these countries, especially Germany, to the large sinks in the North Sea. If additional restrictions like source-sink matching, acceptance issues and injection rates constraints are taken into account, the available storage space gets increasingly scarce. [Copyright &y& Elsevier]

Abstract: Ketzin, in the Northeast German Basin (NEGB), is the site for pilot injection of CO2 (CO2SINK project) into a saline aquifer (the Upper Triassic Stuttgart Formation) situated at a depth of about 630–700m. This paper reports the baseline characterization of the reservoir formation based on new core material and well-logs obtained from one injection well and two observations wells, drilled at a distance from 50m to 100m from each other. The reservoir is lithologically heterogeneous and made up by fluvial sandstones and siltstones interbedded with mudstones showing remarkable differences in porosity. The thickest sandstone units are associated with channel sandstone, whose thickness varies over short lateral distances. In-depth petrographic, mineralogical, mineral-chemical, and whole-rock geochemical analysis were performed focusing on the sandstone intervals, which display the best reservoir properties for CO2 injection. The dominantly fine-grained and well to moderately-well sorted, immature sandstones classify as feldspathic litharenites and lithic arkoses. Quartz (22–43wt.%), plagioclase (19–32wt.%), and K-feldspar (5–13wt.%) predominate mineralogically. Muscovite plus illite and mixed-layer minerals are omnipresent (4–13wt.%). Quartz, feldspar, as well as meta-sedimentary and volcanic rock fragments comprise the most abundant detrital components, which often are rimmed by thin, early diagenetic coatings of ferric oxides, and locally of clay minerals. Feldspar grains may be unaltered and optically clear, partially to completely dissolved, partially altered to sheet silicates (mainly illite), or albitized. Analcime and anhydrite constitute the most widespread, often spatially associated pore-filling cement minerals. Authigenic dolomite, barite, and coelestine is minor. The percentage of cements ranges in total from about 5vol.% to 32vol.%. Except of samples intensely cemented by anhydrite and analcime, total porosities of the sandstones range from 13% to 26%. The fraction of intergranular porosity varies between 12% and 21%. About 1–5% porosity has been generated by dissolution of detrital plagioclase, K-feldspar, and volcanic rock fragments. The comparatively large modal abundance of feldspars, micas, chlorite, clay minerals, Fe–Ti-oxides, and analcime account for the richness in Ti, Al, Fe, Mg, Na, and K, and the paucity in Si, of the Stuttgart sandstones relative to mature sandstones. Altogether, these sandstones are comparatively rich in minerals that may potentially react with the injected CO2. [Copyright &y& Elsevier]

Abstract: To test the injection behaviour of CO2 into brine-saturated rock and to evaluate the dependence of geophysical properties on CO2 injection, flow and exposure experiments with brine and CO2 were performed on sandstone samples of the Stuttgart Formation representing potential reservoir rocks for CO2 storage. The sandstone samples studied are generally fine-grained with porosities between 17 and 32% and permeabilities between 1 and 100mD. Additional batch experiments were performed to predict the long-term behaviour of geological CO2 storage. Reservoir rock samples were exposed over a period of several months to CO2-saturated reservoir fluid in high-pressure vessels under in situ temperature and pressure conditions. Petrophysical parameters, porosity and the pore radius distribution were investigated before and after the experiments by NMR (Nuclear Magnetic Resonance) relaxation and mercury injection. Most of the NMR measurements of the tested samples showed a slight increase of porosity and a higher proportion of large pores. [ABSTRACT FROM AUTHOR]

Abstract: This study reports laboratory-measured thermal-conductivity values of Mesozoic sandstones from eight wells (predominantly geothermal boreholes) of the Northeast German Basin (NEGB). The measurements were made on drill core using the optical scanning method. Bulk thermal conductivities of sandstones corrected for in situ thermal conditions range between 2.1 and 3.9W/m/K. In general, the Mesozoic sandstones show a large effective porosity typically ranging between 16% and 30%. Matrix thermal conductivity ranges from 3.4 to 7.4W/m/K. The higher values reflect the large quartz content in sandstone. Based on the in situ thermal conductivity and corresponding interval temperature gradient, obtained from high-precision temperature logs measured under thermal borehole equilibrium, interval heat-flow values were computed in the Middle Buntsandstein section (between 1400 and 1500m) of two boreholes located in the Stralsund area. The heat flow averages to 74mW/m² (Gt Ss 1/85 borehole) and 78mW/m² (Gt Ss 2/85 borehole) and, by adding a heat-flow component of 1.8mW/m² for the heat production in the overburden, are in good correspondence with previously reported surface heat flow of 77mW/m². Based on these values and the temperature log information, thermal conductivity was indirectly calculated for the entire borehole profiles. The discrepancy between laboratory-measured and computed thermal conductivities in the two boreholes is in the order of 0.24 and 0.56W/m/K. Formation in situ thermal conductivity of the Mesozoic section ranges between 1.5 and 3.1W/m/K. [ABSTRACT FROM AUTHOR]

Abstract: In Germany, the construction of extensive greenroofs has been a tradition for over 100 years. This study picked up older Berlin research conducted in 1960, 1982, 1986, 1987, 1990, 1995 and compared it with current findings (). The older research was made either on the old “Tar-Paper-Greenroofs” (TPG-roofs), established between 1880 and 1930, or on the first systematically vegetated Modern Extensive Greenroofs (MEG-roofs), established in the 1980s. This survey compares both roof types and supplements the chronology of analysis. The research showed that MEG and especially TPG are resilient roof types and can last up to 100 years. About 70 vascular plant species were found on the surveyed roofs ( resp. consistency). Regarding the growing media, we could show that total porosity rises over a period of 10 years from 50 to 60%. In the meantime C/N-ratio falls from initially 25 down to 13. While the pH of the slightly acidic TPG-media rose to neutral, the slightly alkaline MEG-media sank down to neutral. With the help of a specially developed vegetation quality index, which incorporates both relative plant coverage and species quantity, we could show that media depth and the grade of sunlight exposition influence floral quality of greenroofs as well as how. According to the specified criteria, the quality of the modern extensive greenroofs is significantly higher than the quality of the 100-year-old ones. Nevertheless, a significant correlation between water holding capacity and vegetation coverage was shown for both roof types. [Copyright &y& Elsevier]

Abstract: Exploration for geothermal resources is often challenging because there are no geophysical techniques that provide direct images of the parameters of interest, such as porosity, permeability and fluid content. Magnetotelluric (MT) and seismic tomography methods yield information about subsurface distribution of resistivity and seismic velocity on similar scales and resolution. The lack of a fundamental law linking the two parameters, however, has limited joint interpretation to a qualitative analysis. By using a statistical approach in which the resistivity and velocity models are investigated in the joint parameter space, we are able to identify regions of high correlation and map these classes (or structures) back onto the spatial domain. This technique, applied to a seismic tomography-MT profile in the area of the Groß Schönebeck geothermal site, allows us to identify a number of classes in accordance with the local geology. In particular, a high-velocity, low-resistivity class is interpreted as related to areas with thinner layers of evaporites; regions where these sedimentary layers are highly fractured may be of higher permeability. [Copyright &y& Elsevier]

Abstract: Small-angle neutron scattering (SANS) analysis and transmission electron microscopy evidence suggest the occurrence of nanoscale porosity in commercial-purity titanium processed by equal-channel angular pressing (ECAP). SANS data were produced at two different facilities (GKSS, Germany; and Los Alamos, USA) and were analysed using three different methods. The results are consistent and yield a conclusive picture of the distribution of the scattering centres, which are believed to be associated with nanoporosity. Back pressure applied during ECAP tends to reduce the average pore size, which also depends on the processing route used. The results of the study strongly suggest that ECAP leaves a footprint in titanium in the form of a population of polydispersed nanovoids, which may play an important role in subsequent processing of the material. [Copyright &y& Elsevier]

Abstract: Physical properties of the deposits in the DYNAS study area, the Mecklenburg Bay, were investigated using sediment echosounders and laboratory analysis were carried out on undisturbed short sediment cores. Wet bulk densities of about 1.2 g/cm3 for mud and up to 1.9 g/cm3 for silty sand were found in surface sediments of the Mecklenburg Bay. Sediment density–depth functions were approximated by logarithmic regression functions at different depth intervals. Sediment consolidation was studied by both (i) consolidation tests of sediment samples and (ii) from the void ratio–overburden pressure relation in natural sediments. Low shear strength values of 9–71 Pa were measured at the mud surface. Downcore, a depth gradient of about 14.5 Pa/cm was calculated. Sediments with high silt and sand contents are characterized by shear strength values of up to 3000 Pa. Published formulas derived from erosion studies were used to calculate the critical shear stress using wet bulk density and shear strength. The obtained results demonstrate clearly, that there is still a wide gap in knowledge about the relationships between erosion parameters and sediment physical properties. [Copyright &y& Elsevier]

Abstract: This work investigates effective CO2 storage capacity of a field case example, the Ketzin reservoir (CO2SINK) in Germany with highly heterogeneous permeability and porosity. The present concept of storage capacity coefficients is briefy explained and then extended to widen the usability in the long term. A basecase incorporating the latest geological model is defined, for which storage capacity coefficients are given in the course of time. The effective storage capacity for a injection of 60000 tons of CO2 is 5.7 per mill in terms of pore volume. A sensitivity study on the Net-to-Gross ratio shows, that the applicability of the final effective storage capacity coefficient is limited here. All realisations show about the same effective storage capacity . However, the location of the CO2 mass and the mobility (mobile/immobile gas) varies with the ratio. For increasing ratio, more mobile CO2 mass stays in the sand channels. [Copyright &y& Elsevier]

[Display omitted] • One-step melt-infiltration method is useful for preparing high-Ni-loaded catalyst. • Alkaline earth metals (Ca, Ba, Sr, and Ba) enhance the catalytic activity of Ni/Al 2 O 3. • Ca-Ni/Al 2 O 3 shows the best activity among the alkaline-metal-promoted samples. • Ca addition improves the reducibility of NiO and CO 2 adsorption ability. As part of carbon energy recycling, the CO 2 methanation process in the power to gas technology, which converts the electricity grid into a gas grid [CO 2 + 4H 2 (produced by surplus electricity) → CH 4 ] using a catalytic process, has been developed in the countries such as Germany and Denmark. To achieve an efficient catalytic process, the design of low-cost and high-efficiency catalysts is required. In this study, highly loaded Ni/Al 2 O 3 catalysts (30 wt%) were prepared using the alkaline-earth metals (Mg, Ca, Sr, and Ba) via one-step melt-infiltration (OSMI) method. The Ni active sites were investigated, and the effectiveness of each alkaline-earth metal (Ca, Mg, Sr, and Ba) was determined. The catalytic activity was investigated in the temperature range of 275–400 °C and weight gas hourly velocity (WHSV) of 160,000 mL·g cat −1·h−1 under atmospheric pressure. Ni and alkaline-earth metals were uniformly dispersed into the pore structure of the alumina support. The average metallic Ni particle size of each catalyst was similar (~11 nm), and no severe Ni sintering was observed even at a Ni loading of 30 wt%. Mg-promoted Ni/Al 2 O 3 catalyst was unsuitable for the OSMI method because the reduction of the Ni active sites was not completely accomplished at 400 °C. Ca-promoted Ni/Al 2 O 3 catalyst afforded the best catalytic activity among other metal-promoted Ni/Al 2 O 3 catalysts. Ca increased the CO 2 adsorption amount and reducibility of the Ni active sites, and the optimum Ca loading was 5 wt%. However, the over-loading of Ca (10 wt%) was harmful to the catalytic activity of the Ni active sites. [ABSTRACT FROM AUTHOR]

Abstract: Limestones and karstified limestones (dolostones) from a Permian aquifer in Central Germany were studied by 1H 2D NMR relaxometry and PFG NMR diffusometry, aiming at a non-destructive characterization of the pore space. Information concerning pore size distribution and water diffusion were in accord for different samples of each type of rock, but differed fundamentally between limestones and dolostones. The results of the 2D relaxometry measurements revealed a ratio of surface relaxation times T s 1/T s 2 of about 2 for the limestones and about 4.5 for the dolostones, mirroring the different content of iron and manganese in the solid pore walls. In consideration of thin section interpretation, the corresponding fraction in the T 1–T 2 relaxation time distributions was attributed to interparticle porosity. Porosity of large vugs is clearly displayed by relaxation times longer than 1 s in the dolostones only. A third fraction of the total water-saturated pore space in the dolostones, which is clearly displayed in the 2D relaxation time distributions at the smallest relaxation times and a T s 1/T s 2 ratio of about 12, is attributed to intrafossil porosity. The porosity classification, basing on non-destructive NMR experiments, is verified by mercury intrusion porosimetry and thin section interpretation. [Copyright &y& Elsevier]

The fluvial-aeolian Rotliegend succession exposed in a quarry near Magdeburg (Flechtinger Höhenzug, Northern Germany) is an analogue for deeply-buried gas-bearing Rotliegend sandstones in the Southern Permian Basin. The spatial configuration of bounding surfaces within this succession was reconstructed with reference to twelve profiles with 926 sample points. Generally sub-horizontal interdune migration surfaces were surveyed, and the areal extent of small-scale superimposition surfaces and the thicknesses of intervening strata were measured. Based on these observations and also on the extent of different lithofacies types and on corresponding porosity and permeability data, a 3D lithofacies model (including bounding surface configurations) incorporating porosity and radial permeability was created using PETRELT™ software. In the quarry, aeolian sandstones approximately 12 m thick (φ∼ 5-11 vol. %, κradial∼ 0.01-10mD) are separated into a number of tabular bed sets by sub-horizontal interdune migration surfaces. The surfaces are often associated with thin pelitic intervals with low permeabilities which originate from deflation and sheet flow events. Aeolian deposits consist mainly of two lithotypes: low-angle cross-bedded, and steeply cross-bedded medium-grained sandstones. Superimposition surfaces occur at the base of the low-angle cross-bedded sandstone bodies. The highest porosities and permeabilities occur within the steeply cross-bedded sandstones, reflecting intense eodiagenetic calcite and quartz cementation with subsequent calcite dissolution. The low-angle cross-bedded sandstones may act as flow baffles. This outcrop-derived, high resolution model may contribute to a better understanding of the subsurface architecture and reservoir properties of aeolian-fluvial successions. Taking into consideration the centimetre- to metre-scaled inhomogeneities observed at outcrop, lithotype modelling with reference to the occurrence of bounding surfaces may help to predict how similar reservoir rocks are partitioned. [ABSTRACT FROM AUTHOR]

The Rotliegend of the North German basin is the target reservoir of an interdisciplinary investigation program to develop a technology for the generation of geothermal electricity from low-enthalpy reservoirs. An in situ downhole laboratory was established in the 4.3 km deep well Groβ Schönebeck with the purpose of developing appropriate stimulation methods to increase permeability of deep aquifers by enhancing or creating secondary porosity and flow paths. The goal is to learn how to enhance the inflow performance of a well from a variety of rock types in low permeable geothermal reservoirs. A change in effective stress due to fluid pressure was observed to be one of the key parameters influencing flow properties both downhole and in laboratory experiments on reservoir rocks. Fluid pressure variation was induced using proppant-gel-frac techniques as well as waterfrac techniques in several different new experiments in the borehole. A pressure step test indicates generation and extension of multiple fractures with closure pressures between 6 and 8.4 MPa above formation pressure. In a 24-hour production test 859 m3 water was produced from depth indicating an increase of productivity in comparison with former tests. Different depth sections and transmissibility values were observed in the borehole depending on fluid pressure. In addition, laboratory experiments were performed on core samples from the sandstone reservoir under uniaxial strain conditions, i.e., no lateral strain, constant axial load. The experiments on the borehole and the laboratory scale were realized on the same rock types under comparable stress conditions with similar pore pressure variations. Nevertheless, stress dependences of permeability are not easy to compare from scale to scale. Laboratory investigations reflect permeability variations due to microstructural heterogeneities and the behavior in the borehole is dominated by the generation of connections to large-scale structural patterns. [ABSTRACT FROM AUTHOR]

In a field study, conducted on 10 conventionally managed field sites in Germany, the effects of high axle loads (15–25 Mg) on soil physical properties were investigated. Soil texture classes ranged from loamy sand to silty clay loam. All sites were annually ploughed, and one site was additionally subsoiled to 40 cm depth. In the context of common field operations wheeling was performed either by a sugar beet harvester (45 Mg total mass, 113 kPa average ground contact pressure) or a slurry spreader (30 Mg total mass, 77 kPa average ground contact pressure). Soil moisture conditions varied from 3.2 to 32 kPa water tension during this pass. Penetration resistance was measured before the pass. Soil cores were collected in a grid scheme at each site before and after the machine passed. Bulk density, aggregate density, air-filled porosity and air permeability at seven distinct soil water tensions ranging from 0.1 to 32 kPa were determined in these cores taken from three layers (topsoil, plough pan and subsoil).At most sites, a pass by the sugar beet harvester or slurry spreader strongly affected topsoil properties. Bulk density and aggregate density increased while air-filled porosity and air permeability decreased. The plough pan was already severely compacted before wheeling: therefore changes were small. The subsoil showed no changes or only minor signs of compaction. Only at one site, which was subsoiled the year before, significant signs of compaction (i.e. changes in bulk density, air-filled porosity and air permeability) were detected in subsoil layers.The results show that using present-day heavy agricultural equipment does not necessarily lead to severe subsoil compaction in soils where a compacted plough pan already exists. However, fields which were subsoiled leading to an unstable soil structure are in serious danger of becoming severely compacted. [Copyright &y& Elsevier]

— A new non-contact and non-destructive optical scanning instrument provided a large number of high-precision measurements of thermal conductivity tensor components in samples of sedimentary and impact rocks, as well as new insights into interrelations between thermal conductivity and other physical properties. More than 800 core samples (dry and fluid-saturated) of sedimentary rocks from different Russian oil-gas deposits and impact rocks from the well “Nördlingen 1973” drilled in the Ries impact structure (Germany) were studied using optical scanning technology. It was established that the thermal conductivity parallel to the stratification is more informative for petrophysical investigations than the thermal conductivity perpendicular to the layering. Different approaches were developed to estimate porosity, permeability, pore space geometry, and matrix thermal conductivity with a combination of thermal conductivity measurements in dry and fluid-saturated samples and mathematical modelling. These approaches allow prediction of the rock porosity and permeability and their spatial distribution along a well using thermal conductivity measurements performed with the optical scanning instrument directly applied to cores. Conditions and constraints for using Lichtenecker-Asaad's theoretical model for the estimation of porosity and thermal conductivity of sedimentary rocks were determined. A correlation between thermal conductivity and acoustic velocity, porosity, density, and electric resistivity of impact rocks was found for different rock types. New relationships between permeability, electrical and thermal conductivity found for sedimentary rocks are described. [ABSTRACT FROM AUTHOR]

Important factors, such as porosity, respirational O2 consumption, O2 release of the roots and iron oxidation on the root surface, which are involved in the flood tolerance of Phragmites australis were investigated in northern Germany. The porosity of the different organs was determined as 58% for rhizomes, 42% for culms and 23-38 % for adventitious roots. Mean respirational O2 consumption of below ground organs was measured at 5, 10, 15 and 20 °C as respectively 0.25, 0.5, 0.8 and 1.75 nmol O2 g-1 dry mass s-1. The saturation concentration was estimated to be less than 0.017 mmol O2 l-1 up to 15 °C and 0.03 mmol O2 l-1 at 20°C. From values of the root O2 gas exchange obtained from entire plants predictions are made concerning the O2 status of the roots under field conditions throughout the year. The O2 release for a reed stand was calculated as 65-129 mg O2 m-2 h-1 in summer conditions. The oxidation power of the roots was further demonstrated by the development of iron hydroxide- plaques on the root surface. [ABSTRACT FROM AUTHOR]

The physical properties and mechanical behaviour of impactites are an important parameter in fluid flow models and slope stability and landscape evolution assessments for heavily impacted planetary bodies. We first present porosity, permeability, Young's modulus, and uniaxial compressive strength measurements for three suevites from the Ries impact crater (Germany). Porosity ranges from 0.18 to 0.43, permeability from 5.8 × 10−16 to 5.1 × 10−14 m2, Young's modulus from 1.4 to 8.1 GPa, and uniaxial compressive strength from 7.3 to 48.6 MPa. To explore their mechanical behaviour, we performed triaxial deformation experiments on these samples at a range of confining pressures. The brittle–ductile transition for the lowest (0.25) and highest (0.38) porosity suevite samples was at a confining pressure of ~30 and ~10 MPa, respectively (corresponding to, for example, depths of ~1 and ~4 km on Mars, respectively). Microstructural observations show that the dominant deformation micromechanism during brittle deformation is microcracking, and during ductile deformation is distributed cataclastic pore collapse. We show that a theoretically grounded permeability model for welded granular media accurately captures the permeability of the studied suevites, and we use micromechanical models to glean insight as to their mechanical behaviour. Finally, we upscale our laboratory measurements to provide physical property values for length scales more relevant for large-scale models, and we compare these data with those for basalt (a lithology representative of the surface of the inner Solar System bodies). These analyses show how macroscopic fractures serve to increase the permeability and decrease the strength and Young's modulus of suevite and basalt. We also find, for example, that basalt can be a factor of 2–5 stronger than suevite in the shallow crust. Our study suggests, therefore, that the rock masses comprising older, bombarded crusts are substantially weaker and more porous and permeable than the younger plains material on these bodies. These findings should be considered in large-scale fluid flow modelling and when providing crustal strength estimates or slope stability assessments for planetary bodies on which protracted records of impact bombardment are preserved. • We provide porosity, permeability, Young's modulus, and strength values for suevite. • Triaxial experiments suggest a shallow brittle–ductile transition for suevite. • A theoretical model for granular materials captures the permeability of suevite. • Petrophysical properties of suevite are upscaled for use in large-scale models. • We outline the implications of these data for impacted planetary bodies. [ABSTRACT FROM AUTHOR]

Introduction: Articular surface replacement (ASR) XL implants exhibit higher-than-expected revision rates, blood ion concentrations and soft tissue lesions, making revisions troublesome and potentially unsatisfying. Appropriate techniques and outcomes in ASR XL revisions are rarely documented. The aims of this study were the assessments of pre-revision data, post-revision clinical and radiographic outcomes and ion levels in isolated acetabular ASR XL revisions performed using highly porous titanium cups and Delta ceramic articulations., Methods: 18 isolated acetabular ASR XL revisions in 16 patients were performed using Ti-Por cups (Adler Ortho, Milan, Italy) and Delta bearings (CeramTec, Plochingen, Germany). Pre-revision demographic, clinical, radiological and implant-related features were assessed. Clinical and radiographic parameters (cup positioning, osseointegration) after revisions were evaluated at a minimum follow-up of 5 years. Ion concentrations in blood and urine were collected in pre-revision setting and 1 year after revision., Results: 4 complications occurred in 3 different revisions (16.7%), 1 dislocation, 2 infections, 1 psoas impingement. No re-revision was performed at 5 years (1 scheduled arthroscopy). Good clinical outcomes were achieved (HHS score: 88.3 ± 9.2). All the cups showed reassuring signs of osseointegration (>3 parameters). Blood ion concentrations significantly decreased: patients with Co blood ion concentration over the threshold (7 μg/l) decreased from 76.5% to 0%. No pre-revision or intraoperative data influenced the revision outcomes., Conclusions: Highly porous titanium cups and Delta ceramic articulations provided reliable mid-term clinical and radiographic outcomes in isolated acetabular ASR XL revisions. Ion concentrations significantly decreased. Multicentre prospective controlled studies are required to confirm these preliminary outcomes.

We present a new statistical variance approach to characterize pore space related property heterogeneities in reservoir rocks. Tomography data has been obtained from either synchrotron or lab-based µ-CT measurements of sandstones using advanced image segmentation techniques. The rock samples have been processed according to the Digital Rock Physics concept using the high performance Navier-Stokes flow solver of GeoDict (Math2Market GmbH, Germany). The impact of structural and flow-field matrix modifications due to mineral dissolution, precipitation and gas instrusion in autoclave experiments on permeability and porosity are evaluated. Furthermore, grain pattern alteration and its effects on the representative elementary volume (REV) characterization has been studied. Variances of digital flow-fields and structures in pore (2µm) and plug-scale (13µm) resolution are compared using an algorithm developed to evaluate anisotropic heterogeneities in 3D volumes. Multiple geostatistical tools have been applied to evaluate changes in fluid-rock interactions during the alteration events. Computational steady state flow calculations and flow simulations were performed on the digitized structures. For the REV variance analysis, correlation coefficients of pore-grain composition patterns were coupled with simulated flow velocities in the pore space. A new approach with the objective to merge spatial structure patterns with computed flow field data has been studied. Probability density functions and variance analyses illustrate a wide variation between flow velocities and pore space geometries in the samples. Precipitation events tend to clog the pore space causing higher local fluid velocities due to decreasing permeability. On the other hand, gas intrusion induces fluid-gas-mineral interactions due to an opening of new pores with decreasing flow-field and pore-grain pattern variances. Furthermore, it becomes apparent that an open porosity is a prerequisite for an accurate evaluation of pore space alteration. Upscaling efforts based on the variance analysis are indicating first reliable results. [ABSTRACT FROM AUTHOR]

Particle Swarm Optimization (PSO) has received considerable attention as a global optimization technique from scientists of different disciplines around the world. In this article, we illustrate how to use PSO for inverse modeling of a coupled flow and transport groundwater model (MODFLOW2005-MT3DMS) in a fractured gneiss aquifer. In particular, the hydroPSO R package is used as optimization engine, because it has been specifically designed to calibrate environmental, hydrological and hydrogeological models. In addition, hydroPSO implements the latest Standard Particle Swarm Optimization algorithm (SPSO-2011), with an adaptive random topology and rotational invariance constituting the main advancements over previous PSO versions. A tracer test conducted in the experimental field at TU Bergakademie Freiberg (Germany) is used as case study. A double-porosity approach is used to simulate the solute transport in the fractured Gneiss aquifer. Tracer concentrations obtained with hydroPSO were in good agreement with its corresponding observations, as measured by a high value of the coefficient of determination and a low sum of squared residuals. Several graphical outputs automatically generated by hydroPSO provided useful insights to assess the quality of the calibration results. It was found that hydroPSO required a small number of model runs to reach the region of the global optimum, and it proved to be both an effective and efficient optimization technique to calibrate the movement of solute transport over time in a fractured aquifer. In addition, the parallel feature of hydroPSO allowed to reduce the total computation time used in the inverse modeling process up to an eighth of the total time required without using that feature. This work provides a first attempt to demonstrate the capability and versatility of hydroPSO to work as an optimizer of a coupled flow and transport model for contaminant migration., (Copyright © 2014 Elsevier B.V. All rights reserved.)

This special issue compiles invited and contributed papers of the 9th International Conference and Workshop "Biological Barriers", 29 February-9 March 2012 at Saarland University, Saarbrücken Germany., (Copyright © 2013. Published by Elsevier B.V.)

This article reports fibre-optic oxygen measurements on a reactive mine waste heap located in the polymetallic sulphide mine district of Freiberg in south-eastern Germany. The heaped material consists of sulphide-bearing tailings from a processing plant of a lead-zinc mine. Mine waste material was deposited in the water phase after separation of mining ores in a flotation process. The tailing impoundment is partly covered with coarse sand and topsoil. Oxygen profiles were monitored during one year at eleven locations showing different physical and mineralogical compositions. At each location a borehole was drilled where the optic sensors were installed at 2-5 different depths. After installation the oxygen profiles were monitored seven times during one year from 2006-2007 and three to five oxygen profiles at each location were obtained. Oxygen measurements were accompanied by physical, chemical and mineralogical data of the tailing material. Additionally, a detailed mineralogical profile was analysed at a location representative for the central part of the heap, where the cemented layers show lateral continuity. Results showed that cemented layers have a significant influence on natural attenuation of the toxic As and Pb species owing to their capacity of water retention. The measured oxygen profiles are controlled by the zone of active pyrite weathering as well as by the higher water content in the cemented layers which reduces gaseous atmospheric oxygen supply. In contrast, gypsum bearing hardpans detected at three other locations have no detectable influence on oxygen profiles. Furthermore, the grain size distribution was proved to have a major effect on oxygen diffusivity due to its control on the water saturation. Temporal changes of the oxygen profiles were only observed at locations with coarse sediment material indicating also an important advective part of gas flux., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Background: The recommended standard for treatment of perigraft seroma (PS) is the graft removal and the reconstruction using an alternative prosthesis. We assumed that a fibrin sealing of the outer surface of expanded polytetrafluoroethylene (ePTFE) grafts would prevent leakage and used this technique in the treatment and prevention of PS., Methods: Over a 10-year period, 24 patients were treated for PS after subcutaneous implantation of ePTFE grafts (14 arterial bypasses and 10 arteriovenous grafts). Affected graft segments were temporarily removed and underwent sequential fibrin sealing technique before reimplantation. In addition, an in vitro experiment was carried out to demonstrate the efficacy of fibrin sealing to prevent leakage through the ePTFE graft wall, after its hydrophobic barrier was destroyed by filling with saline solution under pressure., Results: A cure of PS was observed in 20 patients (84%) at a follow-up period of 37 ± 18 months. A later graft infection was not seen in any patient. The patency rate of reconstructed grafts appears to be unaffected. In the performed experiment we have demonstrated an elimination of leakage through the graft wall by the fibrin sealing technique., Conclusions: Sequential fibrin sealing of the outer surface is an effective way to treat PS in ePTFE grafts. However, failure of this treatment cannot be precluded. Further studies are necessary that may provide further insights into the causes and best treatment of PS and the possibly important role of PS in the aneurysm enlargement after complete endovascular exclusion with ePTFE endografts., (Copyright © 2010 Annals of Vascular Surgery Inc. Published by Elsevier Inc. All rights reserved.)

The sensitivity of DFO (1,8-diazafluoren-9-one), a substance known since 1989, is clearly superior to that of ninhydrin for the visualization of latent fingerprints. Nevertheless DFO has not replaced ninhydrin in Germany up to now. One reason is its unreliability. The DFO working solutions commonly used in Germany tend to become cloudy very fast during application or to form second phases. According to some reports, these DFO solutions often produce unsatisfactory results in the detection of latent fingerprints, and additional prints may become visible after an extra treatment with ninhydrin. This means that these DFO applications are susceptible to failure and do not possess enough robustness. Now a new, more robust application of DFO is presented, which is also better adapted to the requirements of industrial safety. Moreover, the working solution is prepared from a stock solution that has a stability of more than six months, so that the required quantity is always available.

Iron oxide encrustations are formed on black slate surfaces during oxidative weathering of iron sulfide and phosphate bearing, organic matter-rich slates. Synchronously, trace elements are released during ongoing weathering. Laser ablation ICP-MS analyses of a weathered and encrusted slate showed that major portions of the V, Cu, As, Mo, Pb, Th, and U reside in the encrustation.Recently a potential relationship between several micrometer to 500 nm surface topography roughness of such encrustations and its uranium concentration was shown. Based on laser scanning microscopy measurements, the present study shows that this interrelation must be expanded to small submicron-sized half-pores with diameters between 100 nm and 500 nm. We demonstrate that the relationship is not limited to topography variations of a single encrustation in the hand-specimen scale. Surface topography and geochemical analyses of iron oxide encrustations from several locations but from the same geochemical environment and with similar weathering history showed that the concentrations of U, P, Cu, and Zn correlate inversely with the surface roughness parameter F. This parameter represents the total surface area and is - in this case - a proxy for the root-mean square surface roughness Rq.This study substantiates the environmental importance that micrometer- to submicrometer topography variations of fluid-rock interfaces govern the trapping of trace elements.

Nitrate was analysed in pore-waters with high ionic strength. Extremely high concentrations of dissolved ferrous iron interfere common analytical methods. The automatic photometrical procedure based on the cadmium reduction method is often used for analysis of nitrate in water samples (continuous flow analysis CFA). An integrated dialysis usually serves for sample dilution and (or) sample purification (from particles). Iron was precipitated as iron hydroxide due to the imidazole buffer system (pH 7.5). The dialysis membrane is an effective barrier for iron hydroxide particles to prevent interferences within the cadmium column or the flow-cell. However, dialysis membrane is blocked successively after analysis of several iron-rich pore-water samples by agglomeration of precipitated iron. The blocking of nitrate diffusion through the dialysis membrane is tantamount to a decrease of analytical sensitivity to recognise by decreasing photometrical extinction. Minimising the iron deposition within the dialyser solved the problem. A simple modification of the CFA apparatus was found to keep the analytical sensitivity nearly constant: The mixing coil for the imidazole buffer was considerably elongated. Nearly all iron hydroxide was deposited at the glass coil surface installed before the dialyser. At least 50 iron-rich samples could be analysed within one sample queue with a loss of sensitivity <10%. The recovery of nitrate was about 95%, demonstrated by spiking experiments.

In this study the morphology, physical properties, surface chemical characteristics and microstructure of the Vascugraft arterial prosthesis have been investigated. This is a novel microporous polyurethane device, recently developed by the company Braun-Melsungen AG in Germany for use as a small calibre arterial substitute. This comparative study included two other synthetic grafts: the Mitrathane prosthesis, a hydrophilic prototype polyetherurethane urea graft with closed internal pores, and the commercially successful expanded polytetrafluoroethylene reinforced Goretex prosthesis with an open microporous structure. The Vascugraft prosthesis contains a network of fused microfibres of varying thickness and orientation which provide open and communicating pores similar in size to those in the Goretex material. In addition, they extend from one side of the graft wall to the other. As well as having superior longitudinal and radial compliance to the reinforced Goretex device, the Vascugraft prosthesis has more than adequate bursting and suture retention strengths. Through the use of contact angle measurements, electron spectroscopy for chemical analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry and molecular weight analysis by size exclusion chromatography, the surface of the Vascugraft prosthesis has been shown to be uniquely hydrophobic, as well as containing carbonate groups within an aliphatic polyesterurethane polymer. In addition, variations in micro-phase separation structure of hard and soft segment domains between different sizes and batches of product are marginal. Because of the interesting physical and chemical properties, it is recommended that in vitro biocompatibility and biostability studies be undertaken prior to using the prosthesis in animal or clinical trials.