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The composition of mineral, thermal or deep groundwaters is of interest for several geotechnical applications, such as drinking water supply, spas or geothermal energy. A verified and reliable knowledge of temperature, pH, hydrochemical composition and other parameters is crucial to extract fluids with as few technical problems as possible and exploit groundwater reservoirs economically and environmentally sustainable. However, at sites where empirical data are lacking, the correct prediction of fluid properties is often difficult, resulting in considerable economic risks. Here we present the first comprehensive and publicly available database of mineral, thermal and deep groundwaters of Hesse compiled from published and own data. Presently, it contains 1035 datasets from 560 different springs or wells sampled since 1810. A dataset consists of metadata like location, altitude, depth, rock type or stratigraphic unit, information on the water type, references, physical-chemical parameters, concentrations of major, minor and trace elements, content of dissolved and free gases as well as isotope data. The dataset allows the evaluation of time series and distribution of groundwater properties both laterally and vertically. We show a simple statistical evaluation based on the five major hydrogeological regions of Hesse. Our database can be used to re-evaluate genesis and circulation of deep groundwaters, to estimate reservoir temperatures with a solution geothermometer, or to assess groundwater ages by means of isotope data. It can also be useful for a first conception of deep geothermal utilizations. In future, an update and extension of the database is intended.
Rafael Schäffer; Kristian Bär; Sebastian Fischer; Johann-Gerhard Fritsche; Ingo Sass. Mineral, thermal and deep groundwater of Hesse, Germany. 2021, 2021, 1 -25.
AMA StyleRafael Schäffer, Kristian Bär, Sebastian Fischer, Johann-Gerhard Fritsche, Ingo Sass. Mineral, thermal and deep groundwater of Hesse, Germany. . 2021; 2021 ():1-25.
Chicago/Turabian StyleRafael Schäffer; Kristian Bär; Sebastian Fischer; Johann-Gerhard Fritsche; Ingo Sass. 2021. "Mineral, thermal and deep groundwater of Hesse, Germany." 2021, no. : 1-25.
Petrophysical properties are a key element for reservoir characterization but also for interpreting the results of various geophysical exploration methods or geophysical well logs. Furthermore, petrophysical properties are commonly used to populate numerical models and are often critically governing the model results. Despite the common need for detailed petrophysical properties, data are still very scarce and often not available for the area of interest. Furthermore, both the online research for published property measurements or compilations, as well as dedicated measurement campaigns of the selected properties, which require comprehensive laboratory equipment, can be very time-consuming and costly. To date, most published research results are often focused on a limited selection of parameters only, and hence researching various petrophysical properties, needed to account for the thermal–hydraulic–mechanical behaviour of selected rock types or reservoir settings, can be very laborious. Since for deep geothermal energy in central Europe, the majority of the geothermal potential or resource is assigned to the crystalline basement, a comprehensive database of petrophysical properties comprising rock densities, porosity, rock matrix permeability, thermal properties (thermal conductivity and diffusivity, specific heat capacity) as well as rock mechanical properties as compressional and shear wave velocities, unconfined compressive strength, Young's modulus, Poisson's ratio, tensile strength and triaxial shear strength was compiled from measurements conducted at the HydroThermikum lab facilities of the Technical University of Darmstadt. Analysed samples were mostly derived from abandoned or active quarries and natural or artificial outcrops such as road cuts, riverbanks or steep hillslopes. Furthermore, samples of the cored deep wells Worms 3 (samples from 2175–2195 m), Stockstadt 33R (samples from 2245–2267 m), Weiterstadt 1 (samples from 2502–2504 m), Tiefbohrung Groß-Umstadt/Heubach, B/89–B02 and the cored shallow wells (Forschungsbohrung Messel GA 1 and 2) as well as GWM17 Zwingenberg, GWM1A Zwingenberg, Langenthal BK2/05, EWS267/1 Heubach, and archive samples of the Institut für Steinkonservierung e.V. in Mainz originating from a comprehensive large-scale sampling campaign in 2007 were investigated. The database (Weinert et al., 2020b; https://doi.org/10.25534/tudatalib-278) aims to provide easily accessible petrophysical properties of the Mid-German Crystalline Rise, measured on 224 locations in Bavaria, Hessen, Rhineland-Palatinate and Thuringia and comprising 26 951 single data points. Each data point is addressed with the respective metadata such as the sample identifier, sampling location, petrography and, if applicable, stratigraphy and sampling depth (in the case of well samples).
Sebastian Weinert; Kristian Bär; Ingo Sass. Database of petrophysical properties of the Mid-German Crystalline Rise. Earth System Science Data 2021, 13, 1441 -1459.
AMA StyleSebastian Weinert, Kristian Bär, Ingo Sass. Database of petrophysical properties of the Mid-German Crystalline Rise. Earth System Science Data. 2021; 13 (3):1441-1459.
Chicago/Turabian StyleSebastian Weinert; Kristian Bär; Ingo Sass. 2021. "Database of petrophysical properties of the Mid-German Crystalline Rise." Earth System Science Data 13, no. 3: 1441-1459.
Understanding the complex seismic, thermal, hydraulic and mechanical processes active during the hydraulic stimulation or continuous operation of Enhanced Geothermal Systems (EGS) requires an accurate description of the pre-existing fractures and faults. However, the three-dimensional characterization of the fracture network is challenging, as direct observation of the discontinuity network at great depth is limited. Fracture image logs and continuous core, which provide line samples through the fracture network, are most valuable in this regard as they provide the most precise option to place constraints on network attributes in stochastic realizations of the fractured rock mass. Among various geometrical attributes, the spatial clustering of fractures plays a critical role on the rock mass properties.
Here, we analyzed the spatial distribution of fractures derived from image log runs in six deep boreholes in crystalline basement rock. In one well, the fracture distribution from continuous core was also available. The wells were drilled to depths between 2-5 km, and were all located in the same tectonic setting of the Upper Rhine Graben, which is recognized for its high geothermal potential. The normalized correlation integral method was employed to define the scaling relationships of fracture patterns. This methodology is demonstrated to be less affected by the finite size effects, delivering reliable estimates of scaling laws.
Detailed analyses of image log datasets revealed fractal scaling with similar fractal dimensions (between 0.85 and 0.96), prevailed over almost two orders of magnitude of scale. The same was true for the fracture distribution derived from the continuous core, although this distribution was found to be more clustered than that derived from image logs in the same well (i.e. the fractal dimension was lower, which may be due to the partial fracture sampling of image logs which have a coarser resolution than continuous core analyses). Analysis of fractures in sub-sections of the core dataset from progressively increasing depths revealed no systematic depth-dependency for the fractal dimension, although a local variation at a scale of hundreds of meters was identified.
Mohammad Javad Afshari Moein; Keith Evans; Benoît Valley; Kristian Bär; Albert Genter. Depth-dependent Clustering Analysis of Fractures in Crystalline Basement Rocks. 2021, 1 .
AMA StyleMohammad Javad Afshari Moein, Keith Evans, Benoît Valley, Kristian Bär, Albert Genter. Depth-dependent Clustering Analysis of Fractures in Crystalline Basement Rocks. . 2021; ():1.
Chicago/Turabian StyleMohammad Javad Afshari Moein; Keith Evans; Benoît Valley; Kristian Bär; Albert Genter. 2021. "Depth-dependent Clustering Analysis of Fractures in Crystalline Basement Rocks." , no. : 1.
The crystalline basement of the Upper Rhine Graben presents an attractive target for deep geothermal projects due to its favourable temperatures and its high potential as a fractured and faulted reservoir system. It is already exploited at several sites, e.g. Soultz-sous-Forêts or Landau, and further projects are currently planned or under development. The crystalline units are furthermore the main source of radiogenic heat production and thus, together with the shallow Moho depth and convective heat transport along large fault zones, significantly contributing to the crustal temperature field. For these reasons, we developed the most detailed 3D geological model of the basement in the northern Upper Rhine Graben to date within the Interreg NWE DGE-ROLLOUT and Hesse 3D 2.0 projects. Due to the small number of very deep boreholes as well as seismic profiles reaching the basement beneath the locally more than 5 km thick sedimentary cover, we additionally used high-resolution magnetic and gravity datasets. In contrast to common deterministic modelling approaches, we performed a stochastic joint inversion of the geophysical data by applying a Monte Carlo Markov Chain algorithm. This method generates a large set of random but valid models, which enables a statistical evaluation of the results, e.g. concerning the model uncertainties. For a realistic attribution of the model, we used existing petrophysical databases of the region and measured the magnetic susceptibility of more than 430 rock samples. As a result of the inversion, high-resolution voxel models of the density and susceptibility distribution were generated, allowing conclusions about the composition and structure of the crystalline crust, which leads to a reduction of uncertainties and risks associated with deep geothermal drillings in the northern Upper Rhine Graben. Furthermore, our model will serve as a basis for realistic simulations of heat transport processes in the fractured basement and a meaningful assessment of the deep geothermal potential in the future.
Matthis Frey; Sebastian Weinert; Kristian Bär; Jeroen van der Vaart; Chrystel Dezayes; Philippe Calcagno; Ingo Sass. 3D Modelling of the Northern Upper Rhine Graben Crystalline Basement by Joint Inversion of Gravity and Magnetic Data. 2021, 1 .
AMA StyleMatthis Frey, Sebastian Weinert, Kristian Bär, Jeroen van der Vaart, Chrystel Dezayes, Philippe Calcagno, Ingo Sass. 3D Modelling of the Northern Upper Rhine Graben Crystalline Basement by Joint Inversion of Gravity and Magnetic Data. . 2021; ():1.
Chicago/Turabian StyleMatthis Frey; Sebastian Weinert; Kristian Bär; Jeroen van der Vaart; Chrystel Dezayes; Philippe Calcagno; Ingo Sass. 2021. "3D Modelling of the Northern Upper Rhine Graben Crystalline Basement by Joint Inversion of Gravity and Magnetic Data." , no. : 1.
Petrophysical and mechanical rock properties are key parameters for the characterization of the deep subsurface in different disciplines such as geothermal heat extraction, petroleum reservoir engineering or mining. They are commonly used for the interpretation of geophysical data and the parameterization of numerical models and thus are the basis for economic reservoir assessment. However, detailed information regarding petrophysical and mechanical rock properties for each relevant target horizon is often scarce, inconsistent or distributed over multiple publications. Therefore, subsurface models are often populated with generalized or assumed values resulting in high uncertainties. Furthermore, diagenetic, metamorphic and hydrothermal processes significantly affect the physiochemical and mechanical properties often leading to high geological variability. A sound understanding of the controlling factors is needed to identify statistical and causal relationships between the properties as a basis for a profound reservoir assessment and modeling. Within the scope of the GEMex project (EU H2020, grant agreement no. 727550), which aims to develop new transferable exploration and exploitation approaches for enhanced and super-hot unconventional geothermal systems, a new workflow was applied to overcome the gap of knowledge of the reservoir properties. Two caldera complexes located in the northeastern Trans-Mexican Volcanic Belt – the Acoculco and Los Humeros caldera – were selected as demonstration sites. The workflow starts with outcrop analog and reservoir core sample studies in order to define and characterize the properties of all key units from the basement to the cap rock as well as their mineralogy and geochemistry. This allows the identification of geological heterogeneities on different scales (outcrop analysis, representative rock samples, thin sections and chemical analysis) enabling a profound reservoir property prediction. More than 300 rock samples were taken from representative outcrops inside the Los Humeros and Acoculco calderas and the surrounding areas and from exhumed “fossil systems” in Las Minas and Zacatlán. Additionally, 66 core samples from 16 wells of the Los Humeros geothermal field and 8 core samples from well EAC1 of the Acoculco geothermal field were collected. Samples were analyzed for particle and bulk density, porosity, permeability, thermal conductivity, thermal diffusivity, and heat capacity, as well as ultrasonic wave velocities, magnetic susceptibility and electric resistivity. Afterwards, destructive rock mechanical tests (point load tests, uniaxial and triaxial tests) were conducted to determine tensile strength, uniaxial compressive strength, Young's modulus, Poisson's ratio, the bulk modulus, the shear modulus, fracture toughness, cohesion and the friction angle. In addition, X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses were performed on 137 samples to provide information about the mineral assemblage, bulk geochemistry and the intensity of hydrothermal alteration. An extensive rock property database was created (Weydt et al., 2020; https://doi.org/10.25534/tudatalib-201.10), comprising 34 parameters determined on more than 2160 plugs. More than 31 000 data entries were compiled covering volcanic, sedimentary, metamorphic and igneous rocks from different ages (Jurassic to Holocene), thus facilitating a wide field of applications regarding resource assessment, modeling and statistical analyses.
Leandra M. Weydt; Ángel Andrés Ramírez-Guzmán; Antonio Pola; Baptiste Lepillier; Juliane Kummerow; Giuseppe Mandrone; Cesare Comina; Paromita Deb; Gianluca Norini; Eduardo Gonzalez-Partida; Denis-Ramón Avellán; José Luis Macías; Kristian Bär; Ingo Sass. Petrophysical and mechanical rock property database of the Los Humeros and Acoculco geothermal fields (Mexico). Earth System Science Data 2021, 13, 571 -598.
AMA StyleLeandra M. Weydt, Ángel Andrés Ramírez-Guzmán, Antonio Pola, Baptiste Lepillier, Juliane Kummerow, Giuseppe Mandrone, Cesare Comina, Paromita Deb, Gianluca Norini, Eduardo Gonzalez-Partida, Denis-Ramón Avellán, José Luis Macías, Kristian Bär, Ingo Sass. Petrophysical and mechanical rock property database of the Los Humeros and Acoculco geothermal fields (Mexico). Earth System Science Data. 2021; 13 (2):571-598.
Chicago/Turabian StyleLeandra M. Weydt; Ángel Andrés Ramírez-Guzmán; Antonio Pola; Baptiste Lepillier; Juliane Kummerow; Giuseppe Mandrone; Cesare Comina; Paromita Deb; Gianluca Norini; Eduardo Gonzalez-Partida; Denis-Ramón Avellán; José Luis Macías; Kristian Bär; Ingo Sass. 2021. "Petrophysical and mechanical rock property database of the Los Humeros and Acoculco geothermal fields (Mexico)." Earth System Science Data 13, no. 2: 571-598.
Petrophysical properties are key to populating local and/or regional numerical models and to interpreting results from geophysical investigation methods. Searching for rock property values measured on samples from a specific rock unit at a specific location might become a very time-consuming challenge given that such data are spread across diverse compilations and that the number of publications on new measurements is continuously growing and data are of heterogeneous quality. Profiting from existing laboratory data to populate numerical models or interpret geophysical surveys at specific locations or for individual reservoir units is often hampered if information on the sample location, petrography, stratigraphy, measuring method and conditions is sparse or not documented. Within the framework of the EC-funded project IMAGE (Integrated Methods for Advanced Geothermal Exploration, EU grant agreement no. 608553), an open-access database of lab-measured petrophysical properties has been developed (Bär et al., 2017, 2019b: P3 – database, https://doi.org/10.5880/GFZ.4.8.2019.P3. The goal of this hierarchical database is to provide easily accessible information on physical rock properties relevant for geothermal exploration and reservoir characterisation in a single compilation. Collected data include classical petrophysical, thermophysical, and mechanical properties as well as electrical conductivity and magnetic susceptibility. Each measured value is complemented by relevant meta-information such as the corresponding sample location, petrographic description, chronostratigraphic age, if available, and original citation. The original stratigraphic and petrographic descriptions are transferred to standardised catalogues following a hierarchical structure ensuring inter-comparability for statistical analysis (Bär and Mielke, 2019: P3 – petrography, https://doi.org/10.5880/GFZ.4.8.2019.P3.p; Bär et al., 2018, 2019a: P3 – stratigraphy, https://doi.org/10.5880/GFZ.4.8.2019.P3.s). In addition, information on the experimental setup (methods) and the measurement conditions are listed for quality control. Thus, rock properties can directly be related to in situ conditions to derive specific parameters relevant for simulating subsurface processes or interpreting geophysical data. We describe the structure, content and status quo of the database and discuss its limitations and advantages for the end user.
Kristian Bär; Thomas Reinsch; Judith Bott. The PetroPhysical Property Database (P3) – a global compilation of lab-measured rock properties. Earth System Science Data 2020, 12, 2485 -2515.
AMA StyleKristian Bär, Thomas Reinsch, Judith Bott. The PetroPhysical Property Database (P3) – a global compilation of lab-measured rock properties. Earth System Science Data. 2020; 12 (4):2485-2515.
Chicago/Turabian StyleKristian Bär; Thomas Reinsch; Judith Bott. 2020. "The PetroPhysical Property Database (P3) – a global compilation of lab-measured rock properties." Earth System Science Data 12, no. 4: 2485-2515.
Petrophysical properties are a key element for reservoir characterization but also for interpreting the results of various geophysical exploration methods or geophysical well logs. Furthermore, petrophysical properties are commonly used to populate numerical models and are often critically governing the model results. Despite the common need of detailed petrophysical properties, data is still very scarce and often not available for the area of interest. Furthermore, both the online research for published property measurements or compilations, as well as dedicated measurements campaigns of the selected properties, which requires comprehensive laboratory equipment, can be very time-consuming and costly. To date, most published research results are often focused on a limited selection of parameters only and hence, researching various petrophysical properties, needed to account for the thermal-hydraulic-mechanical behavior of selected rock types or reservoir settings, can be very laborious. Since for deep geothermal energy in central Europe, the majority of the geothermal potential or resource is assigned to the crystalline basement, a comprehensive database of petrophysical properties comprising rock densities, porosity, rock matrix permeability, thermal properties (thermal conductivity and diffusivity, specific heat capacity) as well as rock mechanical properties as compressive and shear wave velocities, unconfined compressive strength, Young’s modulus, Poisson’s ratio, tensile strength and triaxial shear strength was compiled by measurements conducted at the HydroThermikum lab facilities of the Technical University of Darmstadt. Analyzed samples were mostly derived from abandoned or active quarries and natural or artificial outcrops such as road cuts, river banks or steep hill slopes. Furthermore, samples of the cored deep wells Worms 3 (samples from 2175–2195 m), Stockstadt 33R (samples from 2245–2267 m), Weiterstadt 1 (samples from 2502–2504 m), Tiefbohrung Groß-Umstadt/Heubach, B/89–B02 and the cored shallow wells Forschungsbohrung Messel GA 1 and 2 as well as GWM17 Zwingenberg, GWM1A Zwingenberg, Langenthal BK2/05, EWS267/1 Heubach, and archive samples of the Institut für Steinkonservierung e.V. in Mainz originating from a comprehensive large scale sampling campaign in 2007 were investigated. The database (Weinert et al. 2020b, https://doi.org/10.25534/tudatalib-278) aims to provide easily accessible petrophysical properties of the Mid-German Crystalline High, measured on 224 locations in Bavaria, Hesse, Rhineland-Palatinate and Thuringia and comprising 26,951 single data points. Each data point is addressed with the respective metadata such as sample identifier, sampling location, petrography and if applicable stratigraphy and sampling depth (in case of well samples).
Sebastian Weinert; Kristian Bär; Ingo Sass. Database of Petrophysical Properties of the Mid-German Crystalline High. 2020, 2020, 1 -34.
AMA StyleSebastian Weinert, Kristian Bär, Ingo Sass. Database of Petrophysical Properties of the Mid-German Crystalline High. . 2020; 2020 ():1-34.
Chicago/Turabian StyleSebastian Weinert; Kristian Bär; Ingo Sass. 2020. "Database of Petrophysical Properties of the Mid-German Crystalline High." 2020, no. : 1-34.
Petrophysical and mechanical rock properties are key parameters for the characterization of the deep subsurface in different disciplines such as geothermal heat extraction, petroleum reservoir engineering or mining. They are commonly used for the interpretation of geophysical data and the parameterization of numerical models and thus are the basis for economic reservoir assessment. However, detailed information regarding petrophysical and mechanical rock properties for each relevant target horizon are often scarce, inconsistent or distributed over multiple publications. Therefore, subsurface models are often populated with generalized or assumed values resulting in high uncertainties. Furthermore, diagenetic, metamorphic and hydrothermal processes significantly affect the physiochemical and mechanical properties often leading to a high geological variability. A sound understanding of the controlling factors is needed to identify statistical and causal relationships between the properties as a basis for a profound reservoir assessment and modeling. Within the scope of the GEMex project (EU-H2020, GA Nr. 727550), which aims to develop new transferable exploration and exploitation approaches for enhanced and super-hot unconventional geothermal systems, a new workflow was applied to overcome the gap of knowledge of the reservoir properties. Two caldera complexes located in the northeastern Trans-Mexican Volcanic Belt – the Acoculco and Los Humeros caldera – were selected as demonstration sites. The workflow starts with outcrop analogue and reservoir core sample studies in order to define and characterize the properties of all key units from the basement to the cap rock as well as their mineralogy and geochemistry. This allows the identification of geological heterogeneities on different scales (outcrop analysis, representative rock samples, thin sections and chemical analysis) enabling a profound reservoir property prediction. More than 300 rock samples were taken from representative outcrops inside of the Los Humeros and Acoculco calderas, the surrounding areas and from exhumed fossil systems in Las Minas and Zacatlán. Additionally, 66 core samples from 16 wells of the Los Humeros geothermal field and 8 core samples from well EAC1 of the Acoculco geothermal field were collected. Samples were analyzed for particle and bulk density, porosity, permeability, thermal conductivity, thermal diffusivity, heat capacity, as well as ultra-sonic wave velocities, magnetic susceptibility and electric resistivity. Afterwards, destructive rock mechanical tests (point load tests, uniaxial and triaxial tests) were conducted to determine tensile strength, uniaxial compressive strength, Young’s modulus, Poisson’s ratio, bulk modulus, shear modulus, fracture toughness, cohesion and friction angle. In addition, XRD and XRF analyses were performed on 137 samples to provide information about the mineral assemblage, bulk geochemistry and the intensity of hydrothermal alteration. An extensive rock property database was created (Weydt et al. 2020, http://dx.doi.org/10.25534/tudatalib-201.2), comprising 34 parameters determined on more than 2,160 plugs. More than 31,000 data entries were compiled covering volcanic, sedimentary, metamorphic and igneous rocks from different ages (Jurassic to Holocene), thus facilitating a wide field of applications regarding resource assessment, modeling and statistical analyses.
Leandra M. Weydt; Ángel Andrés Ramírez-Guzmán; Antonio Pola; Baptiste Lepillier; Juliane Kummerow; Guiseppe Mandrone; Cesare Comina; Paromita Deb; Gianluca Norini; Eduardo Gonzalez-Partida; Denis Ramón Avellán; José Luis Macías; Kristian Bär; Ingo Sass. Petrophysical and mechanical rock property database of the Los Humeros and Acoculco geothermal fields (Mexico). 2020, 2020, 1 -39.
AMA StyleLeandra M. Weydt, Ángel Andrés Ramírez-Guzmán, Antonio Pola, Baptiste Lepillier, Juliane Kummerow, Guiseppe Mandrone, Cesare Comina, Paromita Deb, Gianluca Norini, Eduardo Gonzalez-Partida, Denis Ramón Avellán, José Luis Macías, Kristian Bär, Ingo Sass. Petrophysical and mechanical rock property database of the Los Humeros and Acoculco geothermal fields (Mexico). . 2020; 2020 ():1-39.
Chicago/Turabian StyleLeandra M. Weydt; Ángel Andrés Ramírez-Guzmán; Antonio Pola; Baptiste Lepillier; Juliane Kummerow; Guiseppe Mandrone; Cesare Comina; Paromita Deb; Gianluca Norini; Eduardo Gonzalez-Partida; Denis Ramón Avellán; José Luis Macías; Kristian Bär; Ingo Sass. 2020. "Petrophysical and mechanical rock property database of the Los Humeros and Acoculco geothermal fields (Mexico)." 2020, no. : 1-39.
Heterogeneity-preserving property models of subsurface regions are commonly constructed by means of sequential simulations. Sequential Gaussian simulation (SGS) and direct sequential simulation (DSS) draw values from a local probability density function that is described by the simple kriging estimate and the local simple kriging variance at unsampled locations. The local simple kriging variance, however, does not necessarily reflect the geological variability being present at subsets of the target domain. In order to address that issue, we propose a new workflow that implements two modified versions of the popular SGS and DSS algorithms. Both modifications, namely, LVM-DSS and LVM-SGS, aim at simulating values by means of introducing a local variance model (LVM). The LVM is a measurement-constrained and geology-driven global representation of the locally observable variance of a property. The proposed modified algorithms construct the local probability density function with the LVM instead of using the simple kriging variance, while still using the simple kriging estimate as the best linear unbiased estimator. In an outcrop analog study, we can demonstrate that the local simple kriging variance in sequential simulations tends to underestimate the locally observed geological variability in the target domain and certainly does not account for the spatial distribution of the geological heterogeneity. The proposed simulation algorithms reproduce the global histogram, the global heterogeneity, and the considered variogram model in the range of ergodic fluctuations. LVM-SGS outperforms the other algorithms regarding the reproduction of the variogram model. While DSS and SGS generate a randomly distributed heterogeneity, the modified algorithms reproduce a geologically reasonable spatial distribution of heterogeneity instead. The new workflow allows for the integration of continuous geological trends into sequential simulations rather than using class-based approaches such as the indicator simulation technique.
Adrian Linsel; Sebastian Wiesler; Joshua Haas; Kristian Bär; Matthias Hinderer. Accounting for Local Geological Variability in Sequential Simulations—Concept and Application. ISPRS International Journal of Geo-Information 2020, 9, 409 .
AMA StyleAdrian Linsel, Sebastian Wiesler, Joshua Haas, Kristian Bär, Matthias Hinderer. Accounting for Local Geological Variability in Sequential Simulations—Concept and Application. ISPRS International Journal of Geo-Information. 2020; 9 (6):409.
Chicago/Turabian StyleAdrian Linsel; Sebastian Wiesler; Joshua Haas; Kristian Bär; Matthias Hinderer. 2020. "Accounting for Local Geological Variability in Sequential Simulations—Concept and Application." ISPRS International Journal of Geo-Information 9, no. 6: 409.
Kristian Bär. Reply to the Review of the Anonymous Referee #2. 2020, 1 .
AMA StyleKristian Bär. Reply to the Review of the Anonymous Referee #2. . 2020; ():1.
Chicago/Turabian StyleKristian Bär. 2020. "Reply to the Review of the Anonymous Referee #2." , no. : 1.
Kristian Bär. Reply to the Interactive Comment of the Anonymous Referee #1. 2020, 1 .
AMA StyleKristian Bär. Reply to the Interactive Comment of the Anonymous Referee #1. . 2020; ():1.
Chicago/Turabian StyleKristian Bär. 2020. "Reply to the Interactive Comment of the Anonymous Referee #1." , no. : 1.
Key requirement for geothermal power production are temperatures of at least 100°C, while the obtainable flow-rate mainly controls the economic viability. Many geotectonic settings only provide such reservoir temperatures in depths of 3 km or more. Hydrothermal systems reach such temperatures only in specific geotectonically active settings, e.g. the Upper Rhine Graben or the Molasse basin in Germany, and usually are already under exploration and exploitation. Besides these easily accessible hydrothermal systems, which only make up a small share of the overall geothermal potential, petrothermal systems in crystalline or metamorphic basement rocks provide a much larger and ubiquitous resource. Locating and quantifying these petrothermal potentials is still a challenging task.
A newly developed exploration scheme for petrothermal potentials is proposed and applied to the crystalline basement of the Mid-German Crystalline High in the federal state of Hesse, Germany. The exploration is composed by three tiers and subdivided in an outcrop analogue study, a conceptual geological 3D-structural model and the estimation of petrothermal potentials based on the comprehensive geothermal 3D-model composed as result of the first two tiers.
On the example of the Mid-German Crystalline High basement rocks, the assessment scheme is demonstrated. Therefore, the geological 3D-structural model which is based on geophysical, structural geological and well data is presented. Petrophysical rock properties such as porosity, grain and bulk density, compressional wave velocity but also thermal conductivity and thermal diffusivity are measured on outcrop analogue samples and fed into a custom-made weighting matrix as basis for a multi-criteria decision making system. Together with additional criteria such as reservoir geometry, rock mechanical and structural geological features, qualitative potential assessment is performed. Quantification of the petrothermal potentials will be applied by the volumetric method and assumption of recovery factors for petrothermal systems based on operating systems worldwide.
Petrothermal potentials are displayed in the geological model.
Sebastian Weinert; Kristian Bär; Günter Zimmermann; Ingo Sass. Assessment of Petrothermal Potentials: An Exploration Scheme for Mid-German Crystalline High Basement Rocks. 2020, 1 .
AMA StyleSebastian Weinert, Kristian Bär, Günter Zimmermann, Ingo Sass. Assessment of Petrothermal Potentials: An Exploration Scheme for Mid-German Crystalline High Basement Rocks. . 2020; ():1.
Chicago/Turabian StyleSebastian Weinert; Kristian Bär; Günter Zimmermann; Ingo Sass. 2020. "Assessment of Petrothermal Potentials: An Exploration Scheme for Mid-German Crystalline High Basement Rocks." , no. : 1.
The outcrop areas of metamorphic rocks in continental setting cover significant regions and their extension zones are even more significant if we also consider the shallow and medium subsurface areas under the sedimentary cover. However, the metamorphic rocks are usually disregarded as potential geothermal reservoirs since they are considered as tight rocks with no or very limited porosity and permeability. Even if this statement is correct, the metamorphic units are frequently associated with a long and complex tectonic evolution and in particular with pre-, syn- and post-metamorphism fractures, which represent potential target zones for the development of geothermal reservoirs. Another limitation to assess the geothermal potentiality of the metamorphic units is the very limited number of deep exploration wells, especially in comparison to other well-investigated reservoirs, such as those located in sedimentary formations.
The anchizone and epizone metasedimentary rocks in Southern Belgium (Wallonia) cover more than 30% of the territory and probably more than 40% if we also consider the metamorphic rocks under the non-metamorphic formations. These statistics are based on the depth interval between 0 km (outcrop) and 6 km, which are reasonable depths for the development of geothermal projects. The encountered lithologies consist of a few km-thick quartzite and slate formations of Lower Palaeozoic and Lower Devonian ages. These formations are associated with different events with the most significant ones regarding this study being the fracturing events related to the formation of the Rhenohercynian basin during the Devonian and the Dinantian times followed by the Variscan orogeny during Upper Carboniferous.
The Havelange borehole was drilled by the Geological Survey of Belgium between 1980-1985 as a gas exploration reaching a maximum depth of 5648 m (MD). The aim of this borehole was to investigate the presence/absence of a Carboniferous gas reservoir located under the main décollement level of the Ardenne Allochthon. Even if the borehole never reached any Carboniferous rocks, it allowed a better characterization of the transition between shallow Lower Famennian shale units and Lower Devonian meta-sedimentary formations, along with Middle Devonian rocks at intermediate depth. The study conducted in the framework of the H2020 MEET project (www.meet-h2020.com) for the Havelange study-site includes the re-investigation of cores, cuttings and log data acquired during the drilling. The laboratory study entails the mineralogical characterisation of the host rocks and fracture zones as well as the petrophysical and rock mechanical characterisation and this borehole material is completed with outcrop analyses and comparable measurements in analogue zones. The lab and field results are cross-matched with the drilling archives and in particular the drilling report indicating the depths of mud losses, representing intervals of great interest for the potential reconversion of this borehole into a geothermal well.
Yves Vanbrabant; Vinciane Stenmans; Christian Burlet; Estelle Petitclerc; Bruno Meyvis; Giorgia Stasi; Rhadityo Arbarim; Kristian Bär; Thomas Goovaerts. Havelange deep borehole (Belgium): a study case for the evaluation of metasedimentary formations as potential geothermal reservoir – H2020 MEET project. 2020, 1 .
AMA StyleYves Vanbrabant, Vinciane Stenmans, Christian Burlet, Estelle Petitclerc, Bruno Meyvis, Giorgia Stasi, Rhadityo Arbarim, Kristian Bär, Thomas Goovaerts. Havelange deep borehole (Belgium): a study case for the evaluation of metasedimentary formations as potential geothermal reservoir – H2020 MEET project. . 2020; ():1.
Chicago/Turabian StyleYves Vanbrabant; Vinciane Stenmans; Christian Burlet; Estelle Petitclerc; Bruno Meyvis; Giorgia Stasi; Rhadityo Arbarim; Kristian Bär; Thomas Goovaerts. 2020. "Havelange deep borehole (Belgium): a study case for the evaluation of metasedimentary formations as potential geothermal reservoir – H2020 MEET project." , no. : 1.
Petrophysical properties are key to populate local and/or regional numerical models and to interpret results from geophysical investigation methods. Searching for rock property values measured on samples from a specific rock unit at a specific location might become a very time-consuming challenge given that such data are spread across diverse compilations and that the number of publications on new measurements is continuously growing and data are of heterogeneous quality. Profiting from existing laboratory data to populate numerical models or interpret geophysical surveys at specific locations or for individual reservoir units is often hampered if information on the sample location, petrography, stratigraphy, measuring method and conditions are sparse or not documented. Within the framework of the EC funded project IMAGE (Integrated Methods for Advanced Geothermal Exploration, EU grant agreement No. 608553), an open-access database of lab measured petrophysical properties has been developed (Bär et al., 20182019: P3 – Database, https://doi.org/10.5880/GFZ.4.8.2019.P3). The goal of this hierarchical database is to provide easily accessible information on physical rock properties relevant for geothermal exploration and reservoir characterization in a single compilation. Collected data include classical petrophysical, thermophysical and mechanical properties and, in addition, electrical conductivity and magnetic susceptibility. Each measured value is complemented by relevant meta-information such as the corresponding sample location, petrographic description, chronostratigraphic age, if available, and original citation. The original stratigraphic and petrographic descriptions are transferred to standardized catalogues following a hierarchical structure ensuring inter-comparability for statistical analysis (Bär et al., 2019: P3 – Petrography, https://doi.org/10.5880/GFZ.4.8.2019.P3.p, Bär et al., 20182019: 3 – Stratigraphy, https://doi.org/10.5880/GFZ.4.8.2019.P3.s. In addition, information on the experimental setup (methods) and the measurement conditions are listed for quality control. Thus, rock properties can directly be related to in-situ conditions to derive specific parameters relevant for simulating subsurface processes or interpreting geophysical data. We describe the structure, content and status quo of the database and discuss its limitations and advantages for the end-user.
Kristian Bär; Thomas Reinsch; Judith Bott. P3 – PetroPhysical Property Database – a global compilation of lab measured rock properties. 2020, 2020, 1 -50.
AMA StyleKristian Bär, Thomas Reinsch, Judith Bott. P3 – PetroPhysical Property Database – a global compilation of lab measured rock properties. . 2020; 2020 ():1-50.
Chicago/Turabian StyleKristian Bär; Thomas Reinsch; Judith Bott. 2020. "P3 – PetroPhysical Property Database – a global compilation of lab measured rock properties." 2020, no. : 1-50.
A successful utilization of deep geothermal resources requires accurate predictions about the distribution of reservoir temperature as well as of the hydraulic processes exerting a direct influence on the productivity of geothermal reservoirs. The aim of this study was to investigate and quantify the influence that regional thermo-hydraulic processes have on the geothermal configuration of potential reservoirs in the German Federal State of Hesse. Specifically, we have addressed the question of how the regional thermal and hydraulic configuration influence the local hydro-thermal reservoir conditions. Therefore, a 3D structural model of Hesse was used as a basis for purely hydraulic, purely thermal and coupled 3D thermo-hydraulic simulations of the deep fluid flow and heat transport. As a result of our numerical simulations, Hesse can be differentiated into sub-areas differing in terms of the dominating heat transport process. In a final attempt to quantify the robustness and reliability of the modelling results, the modelling outcomes were analyzed by comparing them to available subsurface temperature, hydraulic and hydrochemical data.
Nora Koltzer; Magdalena Scheck-Wenderoth; Judith Bott; Mauro Cacace; Maximilian Frick; Ingo Sass; Johann-Gerhard Fritsche; Kristian Bär. The Effects of Regional Fluid Flow on Deep Temperatures (Hesse, Germany). Energies 2019, 12, 2081 .
AMA StyleNora Koltzer, Magdalena Scheck-Wenderoth, Judith Bott, Mauro Cacace, Maximilian Frick, Ingo Sass, Johann-Gerhard Fritsche, Kristian Bär. The Effects of Regional Fluid Flow on Deep Temperatures (Hesse, Germany). Energies. 2019; 12 (11):2081.
Chicago/Turabian StyleNora Koltzer; Magdalena Scheck-Wenderoth; Judith Bott; Mauro Cacace; Maximilian Frick; Ingo Sass; Johann-Gerhard Fritsche; Kristian Bär. 2019. "The Effects of Regional Fluid Flow on Deep Temperatures (Hesse, Germany)." Energies 12, no. 11: 2081.
The Spessart Spa at Bad Soden-Salmünster extracts carbon dioxide bearing thermal brine from three wells. To utilise the thermal brine for balneology in the spa it is necessary to heat the brine, given that the maximum temperature is “only” 23.7 °C. The management of the spa intends to lower financial expenses by increasing the utilisation of renewable energies. This has led to the investigations presented here, focussing on whether hotter brine could be produced by deepening existing wells or drilling new deeper wells. Additionally, optional heat supply from shallow geothermal systems is examined.The wells of Bad Soden-Salmünster are the deepest drill holes in the region reaching a depth of 539 m. Since there are neither deeper wells nor available geophysical exploration data, predicting the geological structure of the deeper underground is a challenging aspect of this exploration. Therefore, a multimethod approach has been chosen here. Firstly, a combination of historical data and new measurements is used to discuss origin and genesis of the thermal brine. Secondly, using literature data and an outcrop analogue study, the geological units beneath Bad Soden-Salmünster are predicted and assigned petrophysical properties. Thirdly, the open-flow potential of the used wells and data from pumping tests are evaluated. Finally, the geothermal potential of the reservoir at Bad Soden-Salmünster is estimated. The chosen multimethod approach is shown to provide a comparatively quick and cost efficient option for establishing a reliable database that enables geothermal exploration decisions as well as future simulations of different geothermal utilisation scenarios.
Rafael Schäffer; Kristian Bär; Ingo Sass. Multimethod exploration of the hydrothermal reservoir in Bad Soden-Salmünster, Germany. Zeitschrift der Deutschen Gesellschaft für Geowissenschaften 2018, 169, 311 -333.
AMA StyleRafael Schäffer, Kristian Bär, Ingo Sass. Multimethod exploration of the hydrothermal reservoir in Bad Soden-Salmünster, Germany. Zeitschrift der Deutschen Gesellschaft für Geowissenschaften. 2018; 169 (3):311-333.
Chicago/Turabian StyleRafael Schäffer; Kristian Bär; Ingo Sass. 2018. "Multimethod exploration of the hydrothermal reservoir in Bad Soden-Salmünster, Germany." Zeitschrift der Deutschen Gesellschaft für Geowissenschaften 169, no. 3: 311-333.
Subsurface temperature is the key parameter in geothermal exploration. An accurate estimation of the reservoir temperature is of high importance and usually done either by interpolation of borehole temperature measurement data or numerical modeling. However, temperature measurements at depths which are of interest for deep geothermal applications (usually deeper than 2 km) are generally sparse. A pure interpolation of such sparse data always involves large uncertainties and usually neglects knowledge of the 3D reservoir geometry or the rock and reservoir properties governing the heat transport. Classical numerical modeling approaches at regional scale usually only include conductive heat transport and do not reflect thermal anomalies along faults created by convective transport. These thermal anomalies however are usually the target of geothermal exploitation. Kriging with trend does allow including secondary data to improve the interpolation of the primary one. Using this approach temperature measurements of depths larger than 1,000 m of the federal state of Hessen/Germany have been interpolated in 3D. A 3D numerical conductive temperature model was used as secondary information. This way the interpolation result reflects thermal anomalies detected by direct temperature measurements as well as the geological structure. This results in a considerable quality increase of the subsurface temperature estimation.
Wolfram Rühaak; Kristian Bär; Ingo Sass. Geostatistical Interpolation of Subsurface Properties by Combining Measurements and Models. 2018, 1 .
AMA StyleWolfram Rühaak, Kristian Bär, Ingo Sass. Geostatistical Interpolation of Subsurface Properties by Combining Measurements and Models. . 2018; ():1.
Chicago/Turabian StyleWolfram Rühaak; Kristian Bär; Ingo Sass. 2018. "Geostatistical Interpolation of Subsurface Properties by Combining Measurements and Models." , no. : 1.
The Los Humeros geothermal system is steam dominated and currently under exploration with 65 wells (23 producing). Having temperatures above 380 ∘C, the system is characterized as a super hot geothermal system (SHGS). The development of such systems is still challenging due to the high temperatures and aggressive reservoir fluids which lead to corrosion and scaling problems. The geothermal system in Acoculco (Puebla, Mexico; so far only explored via two exploration wells) is characterized by temperatures of approximately 300 ∘C at a depth of about 2 km. In both wells no geothermal fluids were found, even though a well-developed fracture network exists. Therefore, it is planned to develop an enhanced geothermal system (EGS). For better reservoir understanding and prospective modeling, extensive geological, geochemical, geophysical and technical investigations are performed within the scope of the GEMex project. Outcrop analogue studies have been carried out in order to identify the main fracture pattern, geometry and distribution of geological units in the area and to characterize all key units from the basement to the cap rock regarding petro- and thermo-physical rock properties and mineralogy. Ongoing investigations aim to identify geological and structural heterogeneities on different scales to enable a more reliable prediction of reservoir properties. Beside geological investigations, physical properties of the reservoir fluids are determined to improve the understanding of the hydrochemical processes in the reservoir and the fluid-rock interactions, which affect the reservoir rock properties.
Leandra M. Weydt; Kristian Bär; Chiara Colombero; Cesare Comina; Paromita Deb; Baptiste Lepillier; Giuseppe Mandrone; Harald Milsch; Christopher A. Rochelle; Federico Vagnon; Ingo Sass. Outcrop analogue study to determine reservoir properties of the Los Humeros and Acoculco geothermal fields, Mexico. Advances in Geosciences 2018, 45, 281 -287.
AMA StyleLeandra M. Weydt, Kristian Bär, Chiara Colombero, Cesare Comina, Paromita Deb, Baptiste Lepillier, Giuseppe Mandrone, Harald Milsch, Christopher A. Rochelle, Federico Vagnon, Ingo Sass. Outcrop analogue study to determine reservoir properties of the Los Humeros and Acoculco geothermal fields, Mexico. Advances in Geosciences. 2018; 45 ():281-287.
Chicago/Turabian StyleLeandra M. Weydt; Kristian Bär; Chiara Colombero; Cesare Comina; Paromita Deb; Baptiste Lepillier; Giuseppe Mandrone; Harald Milsch; Christopher A. Rochelle; Federico Vagnon; Ingo Sass. 2018. "Outcrop analogue study to determine reservoir properties of the Los Humeros and Acoculco geothermal fields, Mexico." Advances in Geosciences 45, no. : 281-287.
The northern Upper Rhine Graben is due to its tectonic setting and the positive geothermal anomaly a key region for geothermal heat and power production in Europe. In this area the Upper Eocene to Lower Oligocene Pechelbronn Group reaches depths of up to 2800 m with temperatures of locally more than 130 ∘C. In order to assess the hydrothermal potential of the Pechelbronn Group a large dataset is compiled and evaluated. Petrophysical parameters are measured on core samples of eight boreholes (courtesy of Exxon Mobil). Additionally, 15 gamma-ray logs, 99 lithology logs as well as more than 2500 porosity and permeability measurements on cores of some of these boreholes are available. The Lower Pechelbronn Beds are composed of fluvial to lacustrine sediments, the Middle Pechelbronn Beds were deposited in a brackish to marine environment and the Upper Pechelbronn Beds consist of fluvial/alluvial to marine deposits. In between the western and eastern masterfaults of the Upper Rhine Graben several fault blocks exist, with fault orientation being sub-parallel to the graben shoulders. During the syntectonic deposition of the Pechelbronn Group these fault blocks acted as isolated depocenters, resulting in considerable thickness and depositional facies variations on the regional and local scale (few tens to several hundreds of meters). Laboratory measurements of sonic wave velocity, density, porosity, permeability, thermal conductivity and diffusivity are conducted on the core samples that are classified into lithofacies groups. Statistically evaluated petrophysical parameters are assigned to each group. The gamma-ray logs serve to verify the lithological classification and can further be used for correlation analysis or joint inversion with the petrophysical data. Well data, seismic sections, isolines and geological profiles are used to construct a geological 3-D model. It is planned to use the petrophysical, thermal and hydraulic rock properties at a later stage to parametrize the model unit and to determine, together with the temperature and thickness of the model unit, the expected flow rates and reservoir temperatures and thus the hydrothermal potential.
Meike Hintze; Barbara Plasse; Kristian Bär; Ingo Sass. Preliminary studies for an integrated assessment of the hydrothermal potential of the Pechelbronn Group in the northern Upper Rhine Graben. Advances in Geosciences 2018, 45, 251 -258.
AMA StyleMeike Hintze, Barbara Plasse, Kristian Bär, Ingo Sass. Preliminary studies for an integrated assessment of the hydrothermal potential of the Pechelbronn Group in the northern Upper Rhine Graben. Advances in Geosciences. 2018; 45 ():251-258.
Chicago/Turabian StyleMeike Hintze; Barbara Plasse; Kristian Bär; Ingo Sass. 2018. "Preliminary studies for an integrated assessment of the hydrothermal potential of the Pechelbronn Group in the northern Upper Rhine Graben." Advances in Geosciences 45, no. : 251-258.
District heating will play an important role for heat provision in temperate and cold climate zones in the future. However, in the context of decarbonizing the heating sector, conventional heat sources have to be replaced by renewable energies. This replacement correlates to the necessity to integrate the fluctuating energy source of solar radiation and thus requires seasonal thermal energy storage. More recently, borehole thermal energy storage systems have been integrated into such district heating concepts. Yet, the potential greenhouse gas emission reduction and the financial benefits of these innovative district heating concepts have not been assessed with respect to the environmental burden and the associated investment cost of the modernization. This study presents a comprehensive environmental and economic life cycle assessment of a fictional district heating system with varying shares of shallow to medium deep borehole thermal energy storage and alternative heat sources replacing conventional capacity. In an exemplary district heating system covering 25 GW h of annual heat demand, borehole thermal energy storage can decrease the greenhouse gas emissions of combined heat and power plants and solar thermal collectors by over 40%. Boundary conditions assumed for the development of the energy market and the existence of subsidies have a significant impact on the emission savings and the levelized cost of heat. Considering a probable increase of energy costs and a growing share of renewables in the electricity mix, a combination of solar thermal collectors and borehole thermal energy storage with a small heat and power plant is the best solution, which is economical even without subsidies. The results of the study promote the construction of medium deep borehole thermal energy storage systems that can help to increase the share of renewable energy in the heating sector at reasonable cost.
Bastian Welsch; Laura Göllner-Völker; Daniel O. Schulte; Kristian Bär; Ingo Sass; Liselotte Schebek. Environmental and economic assessment of borehole thermal energy storage in district heating systems. Applied Energy 2018, 216, 73 -90.
AMA StyleBastian Welsch, Laura Göllner-Völker, Daniel O. Schulte, Kristian Bär, Ingo Sass, Liselotte Schebek. Environmental and economic assessment of borehole thermal energy storage in district heating systems. Applied Energy. 2018; 216 ():73-90.
Chicago/Turabian StyleBastian Welsch; Laura Göllner-Völker; Daniel O. Schulte; Kristian Bär; Ingo Sass; Liselotte Schebek. 2018. "Environmental and economic assessment of borehole thermal energy storage in district heating systems." Applied Energy 216, no. : 73-90.