589 Works

Geophysical borehole logging - using existing data for petrophysical and regional characterisation of claystone formations

Gesa Kuhlmann & Klaus Reinhold
BGR-Dienstbereich Berlin, Germany(1);Claystones in the deep subsurface have various barrier-effective properties for solute transport. Changes in the mineralogical composition (incl. fluids), the structure of claystones in the strict sense, as well for claystone formations in a broader sense, and their regionally different geological development cause a great variety of petrophysical, mineralogical and geochemical properties of claystone sequences. Therefore, sound knowledge of the characteristics of claystone formations is required for the different usage options of the...

Forward stratigraphic modelling of marine petroleum source rocks: the case of the Carson Basin

Samer Bou Daher , Erwan Le Guerroué , Paul Jermannaud & Alcide Thebault
Organic matter rich rocks are the main component of any petroleum system. Marine organic matter deposits form a major part of these rocks and are the source of most oil. Vertical and lateral heterogeneities in marine petroleum source rocks are widely observed and owed to the dynamics of deposition and preservation of marine organic matter. Such source rock heterogeneities add major challenges to hydrocarbon exploration and estimation of resources, therefore, quantification of source rock potential...

Reconstruct the evolution of Milankovtich cycle in Paleozoic and Proterozoic and Earth-Moon separation history

Maoyang Zhou , Huaichun Wu & Qiang Fang
At present, it is difficult to obtain numerical astronomy solutions prior to 50 Ma , which should be two reasons for this. First, the solar system's chaotic behavior, namely, small initial disturbances will greatly affect the results of the numerical model of the earth orbit. Second, we do not fully understand the evolution history of the Earth-Moon separation, that is the distance versus time series. Recently, a new method called "TimeOptMCMC" has been successfully applied...

Nachbergbau: Chancen und Herausforderungen

Dennis Quandt , Tobias Rudolph & Christoph Hilgers
Bergbau im 21. Jahrhundert bedeutet auch Alt- und Nachbergbau, immer geknüpft an die Bewältigung post-montaner Herausforderungen und die Langzeit- und Zukunftsaufgaben. Hiermit einhergehend sind Fragestellungen zu den damit verbundenen Kosten und der Möglichkeit der Weiterentwicklung im Bereich der Standortintegrität und -überwachung. Zusätzlich ist die gesellschaftliche Akzeptanz (engl. „social license to operate“) von Bergbauprojekten immer ein Thema. Die Forderung der Öffentlichkeit nach mehr Informationen bei der Erkundung, der Erschließung, der Produktion und der Stilllegung eines Bergbaustandortes...

Hydro-Mechanical Simulation in Geothermal Reservoirs: Physics and Surrogate Modeling

Ryan Santoso , Denise Degen , Mauro Cacace & Florian Wellmann
Hydro-mechanical (HM) simulations are essential aspects of geothermal reservoir studies to assess the heat production and the associated-environmental impacts, such as seismicity. HM simulations are numerically expensive (especially for large-scale simulations) since they require a relatively fine mesh to capture the complex interplay between the fluid-flow and geomechanical processes. This aspect makes it difficult to perform detailed studies on uncertainties in HM simulations. In this work, we present a comprehensive review and numerical demonstrations about...

The family of battery metals found in European seabed mineral deposits: The MINDeSEA perspective

Javier Gonzalez , Teresa Medialdea , Henrik Schiellerup , Irene Zananiri , Pedro Ferreira , Luis Somoza , Xavier Monteys , Trevor Alcorn , Egidio Marino , Ana Lobato , Thomas Kuhn , Johan Nyberg , Vitor Magalhaes , Rosario Lunar , Boris Malyuk , James Hein & Georgy Cherkashov
Covering 15,000,000 km2, the pan-European seas represent a promising new frontier for the exploration of mineral resources. The GeoERA-MINDeSEA consortium, a cooperative network of 12 Geological Surveys and Marine Institutes, is facing this exploration challenge. 688 seabed mineral occurrences are described in the MINDeSEA database, GIS cartographies and reports, containing valuable information on geology, metallogeny, critical raw materials prospectivity and mineral potential. Five types of mineral deposits are investigated, including seafloor massive sulphides, ferromanganese crusts,...

Rock-hosted life through time - Integrating biosignatures of ancient and modern hydrothermal systems

Florence Schubotz
Recent advances in analytical tools including more sensitive detection techniques have led to the discovery of microbial biosignatures in ultra-low biomass samples such as the oceanic lithosphere. Here, energy fluxes are low and microbial life has adapted to the slow cycling of sparsely available food and nutrient sources along cracks and fissures and the access to Earths chemical energy through water-rock interactions. Nevertheless, our understanding of the habitability of Earths lithosphere and potential connections to...

Ternary porosity systems: New perspectives for Buntsandstein geothermal reservoirs in the Upper Rhine Graben, SW Germany.

Ernst Kiefer , Birgit Müller & Frank Schilling
The clastic Lower Triassic Buntsandstein Formation in the Upper Rhine Graben of SW Germany and NE France has been identified as an attractive geothermal reservoir due to its fracture density and exceptionally high matrix porosity at depth levels of economic geothermal energy extraction. New petrophysical data from deep exploration wells reveal the existence of ternary porosity systems evolved during a multi-phase subsidence history and diagenesis especially at intra-graben structural highs. Primary elements of these porosity...

Hydro-thermal modeling of geothermal energy extraction from Soultz-sous-Forêts, France using supercritical CO2

Mrityunjay Singh , Saeed Mahmoodpour , Kristian Bär & Claire Bossennec
Climate change requires immediate action, and for sustainable development, and uninterrupted energy supply is necessary. Since anthropogenic emission of CO2 in the atmosphere has a major role in climate change, carbon negative energy solutions are the necessity of the time. Geothermal energy is one such renewable source that can assist in achieving an economic solution to low carbon energy. Engineered geothermal systems or enhanced geothermal systems (EGS) are more suitable from an industrial perspective and...

Induced micro-seismicity monitoring in urban context using seismic arrays

Rémi Fiori , Jérôme Vergne , Jean Schmittbuhl , Dimitri Zigone & Sophie Lambotte
The modification of the stress field induced by fluid injection into the ground can generate seismic motions. Their monitoring is a key point to limit the occurrence of impacting events. Generally, this is performed using seismic surface networks, which can be limited by a significant ambient noise level especially in urban contexts. An alternative consists in the installation of stations in the depth of wells to increase the distance with surface ambient noise sources. However,...

A Gaussian process regression model to determine solubility of calcium sulfate in aqueous fluids

Ali Sadighi , Reza Taherdangkooi & Christoph Butscher
The swelling of clay-sulfate rocks is a well-known phenomenon often causing threats to the success of different projects, for instance, geothermal drillings triggered swelling and ground heave with dramatic damages in Staufen, Germany. The origin of clay-sulfate swelling is usually explained by physical swelling due to clay expansion combined with chemical swelling associated with the transformation of anhydrite (CaSO4) into gypsum (CaSO4.2H2O). The swelling leads to about 60% of the volume increase of the rock...

GeoLaB - Geothermal Laboratory in the Crystalline Basement

Thomas Kohl , Eva Schill , Judith Bremer , Günter Zimmermann , Olaf Kolditz & Ingo Sass
In Central Europe, the largest geothermal potential resides in the crystalline basement rock with important hotspots in tectonically stressed areas. To better harvest this energy form under sustainable, predictable and efficient conditions, new focused, scientific driven strategies are needed. Similar to other geo-technologies, the complex processes in the subsurface need to be investigated in large-scale facilities to ensure environmental sustainability. The proposed new underground research laboratory GeoLaB (Geothermal Laboratory in the Crystalline Basement) will address...

Recent case studies and advances of the magnetotelluric method in geothermal exploration

Friedemann Samrock
The magnetotelluric (MT) method is a well-established tool in geothermal exploration. Case studies from all over the world and from different geothermal settings have proven its effectiveness, when it comes to subsurface reservoir characterization and the successful siting of geothermal wells. A reason for MT being a popular tool in geothermal exploration is that the bulk electrical conductivity of the subsurface, as recovered by MT, can be used as a proxy for key geothermal parameters....

Transport mechanisms of hydrothermal convection in faulted sandstone reservoir ----- Implications for kilometer-scale thermal anomalies in Piesberg quarry

Guoqiang Yan , Robert Egert , Maziar Gholami Korzani & Thomas Kohl
A transient 3D model obtained from the Piesberg quarry as an illustrative example is based on idealized structural models that characterize all geological features during Late Jurassic rifting (162 Ma) to infer possible transport mechanisms of fluids leading to the formation of kilometer-scale thermal anomaly. Three-dimensional numerical simulations on hydrothermal convection systems in the faulted sedimentary basins are investigated with the aim to assess the lateral heating capacity of hydrothermal convection systems in faults, using...

Enhancing the contribution of closed systems to geothermal energy generation by increasing the ratio of generated power to the total length of wellbores

Morteza Esmaeilpour , Maziar Gholami Korzani & Thomas Kohl
Geothermal energy extraction through closed systems is a secure approach responding to the global heating demand without contaminating subsurface water and causing seismic events. However, the generated power of conventional closed systems is much lower than those of open systems. Therefore, this study is dedicated to planning a novel closed system, which can produce a significant amount of thermal power. For this purpose, the performance of a single closed-loop deep system with a lengthy horizontal...

The Kieshöhe carbonatites in SW-Namibia – the role of silicatic xenoliths for REE exploration

Benjamin Florian Walter , R. Johannes Giebel , Alan Marlow , Michael Marks , Gregor Markl & Jochen Kolb
Exploration of carbonatite-associated REE-deposits is challenging due to heterogeneous ore distribution and variable and often complex ore mineralogy. The Kieshöhe carbonatite in SW Namibia represents a subvolcanic occurrence hosting dolomite, calcite and ankerite carbonatite dykes, ring dykes and diatremes. Petrography, whole rock geochemistry and microXRF imaging provide insights into the role of silicate xenoliths for the REE mineralization in a subvolcanic environment. Xenolith-rich carbonatites are relatively REE-poor with only minor monazite mineralization, whereas xenolith-free carbonatites...

Simulations with numerical model PCSiWaPro® for the infiltration system of treated wastewater on Sardin village, Syria

Abdulnaser Aldarir , Peter-Wolfgang Graeber , Ian Desmond Gwiadowski & Rene Blankenburg
The improvement of groundwater availability in arid areas by infiltration of treated wastewater will play an important role in the next few years. Small wastewater plant is a good alternative in places where central wastewater treatment is not available. Numerical models can be applied to examine the processes more closely and to examine a large number of scenarios analysing. The study described deals with the numerical modeling of a hypothetical infiltration system at Sarden (Syria)...

OneGeochemistry: Enabling a coordinated online global network of multiple distributed geochemical repositories and databases

Kerstin Annette Lehnert , Lesley Wyborn , Dominik Hezel , Alexander Prent , Kirsten Elger , Geertje ter Maat , Marthe Klöcking & Jens Klump
Since the discipline of ‘geochemistry’ was first defined in 1838, geochemical data has been pervasively acquired and used in the Earth, environmental and planetary sciences and become fundamental for understanding past, present, and future processes in natural systems. Initially, geochemical data was published in hard-copy literature, but as analytical systems became computerised, major digital databases emerged (EarthChem, PetDB, OZCHEM and GEOROC) which revolutionised data access. They have proven the power of re-use of geochemical data...

Closely-spaced carbonate replacement veins: the influence of external stress on focused fluid flow during carbonation of peridotite

Manuel D. Menzel , Janos L. Urai & Estibalitz Ukar
The reaction of serpentinized peridotites with CO2-bearing fluids to listvenite (quartz-carbonate rocks) requires massive fluid flux and maintained permeability despite volume increase. Here we investigate listvenites and serpentinites samples from Hole BT1B of the Oman Drilling Project to improve our understanding of the mechanisms and feedbacks of fracturing and vein formation during peridotite carbonation. The samples are characterized by a high abundance of magnesite veins which are often bundled into closely-spaced, parallel sets. Relative cross-cutting...

Critical metals in the environment

Jörg Schäfer
The overall amount of metals and their variety used for technical applications has been subject to a steep increase during the past decades and is forecast to further develop. Growing metal demand for a wide range of high technology applications, including so-called ‘green’ technologies (e.g. PGM, REEs, Te) drives the economic value of these metals and the related mining efforts. For some of these metals, anthropogenic metal fluxes have outcompeted natural biogeochemical cycles, including plate...

Implementation of the Geological Data Act (Geologiedatengesetz): A digital approach of the Geological Survey of Lower Saxony

Robert Schöner, Jan Sbresny , Jörg Elbracht , Nicole Engel & Hans-Jürgen Brauner
State Authority for Mining, Energy and Geology (LBEG), Hannover, Germany(1);Public access to geological data, especially to data from commercial subsurface geological investigations, was claimed for a long time in the German geoscience community. Since June 30th 2020, the Geological Data Act (Geologiedatengesetz, GeolDG) regulates the public availability of this data and replaces the Mineral Act (Lagerstättengesetz) from 1934. The GeolDG implicates both duties for persons who carry out or commission geological investigations and for the...

Petrology and Geochronology of foidites and melilitites in SW Germany and E France

Thomas Binder , Benjamin F. Walter & Michael A. W. Marks
Foidites and melilitites are strongly SiO2-undersaturated rocks that form by extremely low degrees of partial melting of the metasomatically overprinted lithospheric mantle. In Central Europe, they occur in volcanic fields, dike swarms or as isolated stocks and diatremes. Our detailed study on foidites from SW Germany indicates two distinct age groups with marked differences in mineralogy and mineral chemistry: Based on in-situ U Pb age data (apatite, perovskite, zircon) a Miocene cohort (~ 9–19 Ma)...

Critical Minerals in US Geothermal Brines: Opportunities and Challenges for their Extraction

Ghanashyam Neupane
Geothermal power plants produce a large volume of brine for power generation. Since these brines are the product of long-term water-rock interactions at elevated temperatures at depth, they contain dissolved chemical components including critical and strategic mineral commodities at various concentrations. Despite the low concentrations for many of these minerals, significant quantities of select minerals could be recovered due to the large volumes of brine utilized by geothermal power plants. Over the years, the U.S....

Wall rock contamination and mineralogical modifications in carbonatite dykes of the Palabora Complex, South Africa

R. Johannes Giebel , Benjamin F. Walter , Michael A.W. Marks & Gregor Markl
Contamination of carbonatite melts is often neglected due to a fast magma ascent and low liquidus temperatures. However, increased silicate mineral formation observed in numerous carbonatite occurrences world-wide requires an external Si introduction. Our study demonstrates that carbonatite dykes penetrating different lithologies of Palabora (South Africa) shows different modes of mineralogical modification. In particular Al and Si-rich lithologies show the most significant effects. Besides silicate mineral formation Si introduction may cause directly and indirectly variations...

Time-dependent fracture permeability induced by fluid-rock interactions under intermittent and continuous flow

Chaojie Cheng & Harald Milsch
Fractures are the predominant flow pathways in low-permeability rocks. Understanding the fluid-rock interactions that occur in rock fractures and their effects on fracture aperture variations is important for assessing the sustainability of reservoir productivity. This study presents two long-term flow-through experiments with fractured pure quartz sandstones to investigate how fluid composition affects fracture changes over time. One sample was continuously flowed through with fluids (DI or Si-rich fluid), while the other sample was subjected to...

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