scholarly journals Slates: a potential rock type to extract geothermal energy from the underground?

2020 ◽  
Author(s):  
Johannes Herrmann ◽  
Erik Rybacki ◽  
Wenxia Wang ◽  
Harald Milsch ◽  
Bianca Wagner ◽  
...  
Keyword(s):  
Geothermal Energy ◽  
Rock Type ◽  
Metamorphic Rocks ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
The European Union ◽  
Fracture Permeability ◽  
Horizon 2020 ◽  
Rock Types ◽  
Confining Pressures

<p>Commonly used host rock reservoirs for Enhanced Geothermal Systems (EGS) are composed of granite, as they display highly conductive and sustainable fracture networks after stimulation. However, considering the large amount of metamorphic rocks in Europe’s underground, these rock types may also show a large potential to extract geothermal energy from the subsurface. Within the framework of the European Union’s Horizon 2020 initiative ‘MEET (Multi-Sites EGS Demonstration)’, we are conducting fracture permeability experiments at elevated confining pressures, p<sub>c</sub>, temperatures, T, and differential stresses, </p>

Tracking the development of seismic fracture network by considering the fault rupture method

2020 ◽  
Author(s):  
Taghi Shirzad ◽  
Stanisław Lasocki ◽  
Beata Orlecka‐Sikora
Keyword(s):  
Maximum Amplitude ◽  
Clean Energy ◽  
Velocity Model ◽  
Fracture Network ◽  
P Wave ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
The European Union ◽  
Fault Rupture ◽  
Horizon 2020

<p> In Enhanced Geothermal Systems pressurized injections play a role in developing fracture networks and enhancing the water transmissivity. However, the fractures may also coalesce into undesired pathways for fluid migration to enable the fluids to reach pre-existing faults. The properties of observed seismicity can shed some light on the fracture network development and from the standpoint of the possibility to form such undesired pathways. However, to reach this goal the seismic events should be well parameterized. In particular, the information on fault plane mechanisms is essential, which is often not readily accessible. In this study, we use the rupturing process with an accurate P-wave velocity model, which is obtained by the first arrival P-wave tomography approach, to compensate for an eventual lack of source mechanisms of micro-events. For this purpose, four characteristics of the sources (final/average displacement on the fault, the dimension of fault, rupture velocity and particle velocity) can be considered. A 3D model is defined around the hypocenter of each event, so that the size of this model directly depends on the event magnitude. After calculating the arrival time of the selected phase (e.g., P, S, p or s) for each station, all waveforms are then aligned, and stacked by different stacking (e.g., phase weight, N<sup>th</sup>-root) methods. By considering the maximum amplitude of the stacked waveform which is stimulated by each grid, the rupturing plane and the average velocity of rupturing can be obtained. This information of source can be replaced by the double-couple mechanism to investigate the fractures linking and tracking.</p><p>This work was supported under the <em>S4CE</em>: "Science for Clean Energy" project, which has received funding from the European Union’s Horizon 2020 research and innovation program, under grant agreement No 764810.</p>

scholarly journals Numerical simulation of hydraulic fracturing in enhanced geothermal systems considering thermal stress cracks

2021 ◽  
Author(s):  
Ziyang Zhou ◽  
Hitoshi MIKADA ◽  
Junichi TAKEKAWA ◽  
Shibo Xu
Keyword(s):  
Thermal Stress ◽  
High Temperature ◽  
Hydraulic Fracturing ◽  
Geothermal Energy ◽  
Confining Pressure ◽  
Numerical Results ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Compression Tests ◽  
High Confining Pressure

Abstract With the increasing attention to clean and economical energy resources, geothermal energy and enhanced geothermal systems (EGS) have gained much importance. For the efficient development of deep geothermal reservoirs, it is crucial to understand the mechanical behavior of reservoir rock and its interaction with injected fluid under high temperature and high confining pressure environments. In the present study, we develop a novel numerical scheme based on the distinct element method (DEM) to simulate the failure behavior of rock by considering the influence of thermal stress cracks and high confining pressure for EGS. We validated the proposing method by comparing our numerical results with experimental laboratory results of uniaxial compression tests under various temperatures and biaxial compression tests under different confining pressure regarding failure patterns and stress-strain curves. We then apply the developed scheme to the hydraulic fracturing simulations under various temperatures, confining pressure, and injection fluid conditions. Our numerical results indicate that the number of hydraulic cracks is proportional to the temperature. At a high temperature and low confining pressure environment, a complex crack network with large crack width can be observed, whereas the generation of the micro cracks is suppressed in high confining pressure conditions. In addition, high-viscosity injection fluid tends to induce more hydraulic fractures. Since the fracture network in the geothermal reservoir is an essential factor for the efficient production of geothermal energy, the combination of the above factors should be considered in hydraulic fracturing treatment in EGS.

scholarly journals Geothermal Energy R&D: An Overview of the U.S. Department of Energy’s Geothermal Technologies Office

2021 ◽  
Vol 143 (10) ◽  
Author(s):  
Susan G. Hamm ◽  
Arlene Anderson ◽  
Douglas Blankenship ◽  
Lauren W. Boyd ◽  
Elizabeth A. Brown ◽  
...  
Keyword(s):  
United States ◽  
Geothermal Energy ◽  
The United States ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Geothermal Resources ◽  
Future Directions ◽  
Electricity Grid ◽  
Strategic Goals ◽  
The U.S

Abstract Geothermal energy can provide answers to many of America’s essential energy questions. The United States has tremendous geothermal resources, as illustrated by the results of the DOE GeoVision analysis, but technical and non-technical barriers have historically stood in the way of widespread deployment of geothermal energy. The U.S. Department of Energy’s Geothermal Technologies Office within the Office of Energy Efficiency and Renewable Energy has invested more than $470 million in research and development (R&D) since 2015 to meet its three strategic goals: (1) unlock the potential of enhanced geothermal systems, (2) advance technologies to increase geothermal energy on the U.S. electricity grid, and (3) support R&D to expand geothermal energy opportunities throughout the United States. This paper describes many of those R&D initiatives and outlines future directions in geothermal research.

scholarly journals An analysis of thermodynamic properties in both traditional and enhanced geothermal systems to compare thermal efficiencies

2017 ◽  
Vol 4 ◽  
pp. 103-120
Author(s):  
Samuel Peter Martin ◽  
Alexander Richmond Perry ◽  
Kirill Lushnikov
Keyword(s):  
Energy Source ◽  
Renewable Energy Source ◽  
Geothermal Energy ◽  
Energy Production ◽  
Enhanced Geothermal Systems ◽  
System Efficiency ◽  
Geothermal Systems ◽  
Average Efficiency ◽  
Naturally Occurring ◽  
Geothermal Environments

This meta-study draws upon previous research on both Enhanced Geothermal Systems (EGS) and traditional geothermal systems (GS), using these findings to compare and investigate the thermal efficiency of each system. Efficiency calculations include reservoir enthalpy, maximum drilling well temperature, power output (per unit mass of liquid) and mass flow rate of these systems to determine whether EGS’s are viable as an alternative, more readily available renewable energy source. This meta-study suggests that EGS are more viable than naturally occurring GS in the context of future geothermal energy production as they perform with a similar average efficiency of 10-15% and, in addition, can be used in a wider range of geothermal environments.

scholarly journals Current trends in the development of geothermal resources

Georesursy ◽  
2020 ◽  
Vol 22 (4) ◽  
pp. 113-122
Author(s):  
Alexander N. Shulyupin ◽  
Natalia N. Varlamova
Keyword(s):  
Geothermal Energy ◽  
Technology Development ◽  
Local Heat ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Geothermal Resources ◽  
Current Trends ◽  
Geothermal Fields ◽  
The World ◽  
Development Processes

Based on the analysis of publications in world publications, as well as a generalization of the experience of developing domestic geothermal fields, current trends in the development of geothermal resources are shown. The key trend is considered to be the transition from subsidized to commercial projects, which increases the relevance of research in areas that have a significant impact on the economic efficiency of resource development processes, primarily in the direction of geothermal technologies. In terms of subsidized projects that set research goals, the most relevant are works in the direction of EGS (Enhanced Geothermal Systems). Moreover, there is a tendency towards the creation of international interdisciplinary collaborative research teams. It is noted that the current level of technology development allows producing geothermal energy for use in local heat supply systems practically anywhere in the world. However, given the concentration of power per unit area, the basis of modern geothermal energy is still the direction associated with the rise of deep fluids to the surface in areas characterized by the presence of ascending flows of hot juvenile fluids. It is indicated that Russia is lagging behind the world level of progress in the development of geothermal resources, including in terms of current research and development directions, and measures are proposed to overcome this lag.

Petrology of the ultramafic lamprophyre and associated rocks at Coral Rapids, Abitibi River, Ontario

1994 ◽  
Vol 31 (8) ◽  
pp. 1325-1334
Author(s):  
A. D. Edgar ◽  
L. A. Pizzolato ◽  
G. M. Butler
Keyword(s):  
Rock Type ◽  
Metamorphic Rocks ◽  
Alkaline Rocks ◽  
Rock Types ◽  
Ultramafic Lamprophyre ◽  
Mantle Sources ◽  
Host Rocks ◽  
Uniform Composition ◽  
West Eifel ◽  
Metasomatized Mantle

An ultramafic lamprophyre sill and dikes, and an olivine–melilite-rich dike rock intrude Lower to Middle Devonian sediments and low- to high-grade Archean metamorphic rocks on the west bank of the Abitibi River, Coral Rapids, Ontario. Although previously considered to be kimberlitic, all these rocks contain olivine + clinopyroxene + phlogopite ± melilite, and hence are ultramafic alkaline rocks. The ultramafic lamprophyre can be distinguished from the dike by its lower SiO2, Na2O, Al2O3, and higher MgO and FeO. In contrast the olivine–melilite dike rock has a more uniform composition, characteristically contains melilite, and has higher Cr and Ni contents. Enriched light rare earth element (LREE) chondrite-normalized patterns are similar for all rocks.Olivine, clinopyroxene, and phlogopite have Mg# (Mg# = 100 Mg/(Mg + Fe) mol) typical of minerals in primitive alkaline rocks. Melilite composition is similar to that of igneous melilites. Phlogopites in all rock types are enriched in Ba and F and the degree of enrichment is distinct for each rock type. Accessory minerals include apatite, carbonates, chlorite, sericite, and sodalite (only in the olivine–melilite-bearing rock).The mineralogy and chemistry of the Coral Rapids rocks suggest that they are derived from a primitive olivine melilitite magma that may have evolved by fractionation of small amounts of olivine and clinopyroxene to form these alkaline ultramafic magmas.Xenoliths in the ultramafic lamprophyre sill and in lesser abundance in the olivine–melilite dike rock include olivine, phlogopite, and clinopyroxene-rich mantle-derived assemblages. The similarity between these xenoliths and their host rocks at Coral Rapids and those from southwest Uganda and West Eifel, Germany, suggests that the Coral Rapids rocks may be derived from magmas that originated from metasomatized mantle sources.

scholarly journals Local earthquake tomography at the Los Humeros geothermal field, Mexico

2020 ◽  
Author(s):  
Tania Toledo ◽  
Philippe Jousset ◽  
Emmanuel Gaucher ◽  
Hansruedi Maurer ◽  
Charlotte Krawzcyzk ◽  
...  
Keyword(s):  
Joint Inversion ◽  
Detection Algorithm ◽  
Geothermal Field ◽  
Volcanic Complex ◽  
Geothermal Systems ◽  
The European Union ◽  
Injection Wells ◽  
Geothermal Resources ◽  
Seismic Stations ◽  
Horizon 2020

<p>The GEMex<sup>*</sup> project is a recently finalized European-Mexican collaboration that aimed to improve the understanding of two geothermal fields: Acoculco and Los Humeros Volcanic Complex . These sites are located in the Trans-Mexican Volcanic Belt, a region that hosts numerous active volcanoes and is favorable for geothermal exploitation. Currently, the  Los Humeros Volcanic Complex is one of Mexico’s main geothermal systems with an installed capacity of ~95MW. Many studies have been performed at this site since the 70s highlighting several features and characteristics of the shallow subsurface. However a thorough knowledge of structures and behavior of the system at greater depths is still quite sparse. Hence one main objective of the GEMex project was to conduct several geological, geochemical, and geophysical experiments to investigate deeper structures for future development of local and regional geothermal resources.</p><p>In this framework, for the period of one year (September 2017 to September 2018), a seismic array consisting of 45 seismic stations was set to record continuously at the Los Humeros Volcanic Complex. In this study we analyzed the continuous seismic records to detect the micro-seismicity mainly related to exploitation activities. After applying a recursive STA/LTA detection algorithm, we assembled and manually picked P- and S- phases of a catalog of about 500 local events. The detected events were mostly clustered around injection wells, with fewer events located close to known structures. We use the retrieved catalog to derive a new minimum 1D velocity model for the Los Humeros site. We then performed a joint inversion to obtain the 3D Vp and Vp/Vs structures of the geothermal field. A post-processing averaging of several inversions was also computed to increase resolution of the investigated region. In this study we will show the derived Vp and Vp/Vs models for the  Los Humeros Volcanic Complex to emphasize various underground structures and potentially identify possible variations due to changes in temperature, fluid content, and rock porosity.</p><p> </p><p>*This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 727550 and the Mexican Energy Sustainability Fund CONACYT-SENER, project 2015-04-68074. We thank the Comisión Federal de Electricidad (CFE) for kindly granting the access to the geothermal field for installation and maintenance of seismic stations.</p>

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