During the last two decades, a considerable effort has been made by the Oil and Gas industry to develop automated workflows to describe the uncertainty in the subsurface. The Ensemble Reservoir Tool, developed by the state-owned Norwegian company Equinor, has been a key tool to characterize and history-match real hydrocarbon reservoirs. The modelling goal has been to create repeatable,...
A challenge in deep geothermal projects based on the Enhanced Geothermal System (EGS) is to ensure their successful development and the durability of the operation of deep underground heat exchangers while controlling the risk of inducing potentially seismic events. The management of these risks calls for the development of monitoring methods which could contribute to recognize an unexpected...
The Canadian province of Alberta has the highest per capita CO2-equivalent emissions in Canada, predominantly due to the industrial burning of coal for the generation of electricity and mining operations in the oil sand deposits. The use of Alberta’s geothermal potential could reduce CO2 emissions by substituting at least some reasonable amounts of fossil fuels.
Geothermal research in Alberta...
The Data Centre for deep geothermal energy (CDGP, https://cdgp.u-strasbg.fr) was launched in 2016 by the LabEx G-EAU-THERMIE PROFONDE (http://labex-geothermie.unistra.fr) to preserve, archive and distribute data acquired on geothermal sites in Alsace. More than 30 years of data were collected on the Soultz-sous-Forêts research site, providing an inestimable legacy wealth.
CDGP is part of the...
As a part of the European project called MEET, the geothermal powerplant of Soultz-sous-Forêts (Bas-Rhin, France) is investigating the possibility of producing more energy with the same infrastructure. This research project aims to study the potential increase of electricity production by reinjecting the geothermal fluid at lower temperature. Indeed, during the operation of the powerplant, the...
In the frame of the GEMex Europe-Mexico cooperation project (Horizon 2020 Programme; grant agreement No. 727550), we have performed a series of analogue models investigating the influence of pre-existing faults on caldera collapse and subsequent caldera resurgence. This experimental work aims at investigating the development of caldera collapse and resurgence structures, which may represent...
Significant increased of temperatures affect large crustal volumes of carbonatic rocks often related to high temperature settings (e.g volcanoes sedimentary basements, geothermal areas within thick carbonatic sequences or thick sedimentary sequences in contact with large scale plutons). Forecasting carbonatic rocks physical evolution under temperature gradients is of the utmost importance for...
Connected open pores forming the matrix porosity are important fluid pathways in siliciclastic geothermal and hydrocarbon reservoirs at 2-5 km depth. Therefore, grain rearrangement by mechanical compaction, authigenic mineral formation during early and late diagenesis, as well as chemical compaction have a profound impact on permeability (Taylor et al., 2010; Busch et al., 2017). Petrophysical...
In geothermal systems such as Soultz-sous-Forets, the hydraulic stimulation will ensure the efficient hydraulic exchange between injection and production wells by improving hydraulic conductivity of the fracture network through shear of pre-existing fractures. Shear motion creates permanent changes in hydraulic conductivity because of dilation angle of asperities existed on both sides of...
During March 2018 field works were conducted in the Acoculco and Las Minas areas for both geomechanical and geophysical surveys at the outcrop scale. In particular, were performed: classical ISRM scanlines, photo acquisition for no-contact geomechanical surveys, Electrical Resistivity Tomography, Ultrasonic Pulse Velocity measurements. Moreover, samples were collected for some sites.
Unito...
The occurrence of induced earthquakes is a typical phenomenon in the development and exploitation of geothermal reservoirs targeting crystalline basement. Although most induced earthquakes are of low magnitude and can only be detected by sensitive recording instruments, some isolated earthquakes in the magnitude range ML3.5 have occurred in geothermal reservoirs. Due to their shallow depth,...
Geothermal energy is one of the worldwide most important renewable and base load capable energy sources. It will play a major role in the German energy transition process. In Central Europe, the largest geothermal potential resides in the crystalline basement rock with important hotspots in tectonically stressed areas. To meet the necessary energy demand geothermal involves the production of...
The United Downs Deep Geothermal Project is the first geothermal power project to commence in the UK, situated near Redruth, Cornwall, SW England. Two deep deviated geothermal wells have recently been completed to measured depths of 2393 m and 5275 m (2214 m and 5054 m true vertical depth) in June 2019. The wells target the NNW-SSE-trending Porthtowan Fault Zone (PTFZ) which cuts an Early...
Caldera-related superhot geothermal reservoirs are in many cases underexploited. Primary exploration and production challenges, closely tied to investment risk, are predicting the reservoir and targeting the drilling. Our focus in this contribution is assessing the role of fractures in outcrops and their utility as analogues to the fractures in the geothermal reservoir. Our case study is the...
In the surroundings of Acoculco village in the eastern Trans-Mexican Volcanic Belt, two 2-km-deep geothermal exploration boreholes, 500 m apart, demonstrate a temperature gradient of nearly 150°C per km and a tight reservoir. In this context, the GEMex project considered the Acoculco area as a study area for applying methodologies of analysis for Enhanced Geothermal Systems. The stratigraphy...
Geothermal fluids are used as sustainable, alternative energy source for electricity and heat generation in geothermal power plants. Two general settings are distinguished, using hot fluids in active volcanic regions or using lower temperature geothermal brines in sedimentary basins. It has long been known that the geothermal fluids in active volcanic areas are enriched in e.g., Au, As, Sb, Ag...
Geothermal Power Generated from UK Granites (GWatt)
Exploitation of the UK underground thermal resource has been held back by; 1) knowledge gaps about permeability and fluid/heat flow within the fractured hot rocks, and 2) a perception that the uncertainty associated with drilling problems or limited fluid flow from deep boreholes are too high for the potential financial reward. The...
Understanding the subsurface behavior of the Earth is of high importance for the development of geothermal energy, especially in Chile, which has active volcanoes throughout the country. An area with great potential of geothermal development is the southern zone of Chile. Controlled by volcanic environment widely influenced by cortical fault systems. Several thermal spring manifestations of...
Favorably oriented brittle fault zones in a regional stress field are major targets for geothermal exploration and production. Particularly, knowledge of spatial distribution and orientation of brittle fault zones in crystalline basement rocks contribute to our understanding of structural relationships, fault kinematics, and to natural and induced seismicity in EGS reservoirs. In order to...
While the share of renewables in the power generation sector steadily increases, less attention is paid to the decarbonisation of the heating and cooling sector. Since most industrial nations are located within the moderate climate zone, the global heating and cooling supply is less a matter of energy shortage than a matter of seasonal storage. Aquifer Thermal Energy Storage (ATES) is...
The geothermal field of Salavatlı is located in the north of the middle part of the continental rift zone of the Büyük Menderes within the Menderes Massif, western Anatolia, Turkey and consists of Paleozoic metamorphic rocks and Miocene to Pliocene sedimentary rocks. Paleozoic marbles and quartzites form the geothermal water reservoir in the area with 35 production and reinjection wells in a...
By referring to the volume fracturing technology widely used in shale gas and other unconventional oil and gas resources with low-permeability, the segmented multistage fracturing technology of horizontal wells can be introduced to construct the EGS (Enhanced geothermal system) artificial reservoir. Since the EGS reservoir fracturing exhibits in a form of strong non-uniformity, a horizontal...
ETH Zurich has established the Bedretto Underground Laboratory for Geoenergies (BULG) in the Swiss Central Alps (http://www.bedrettolab.ethz.ch), where hydraulic stimulation techniques and associated induced seismicity will be studied. Purpose of the experiments is to improve the understanding of hydromechanical processes linked to the creation of a deep geothermal reservoir. The BULG is...
Los Humeros volcanic complex hosts one of Mexico’s main geothermal fields, which is operated by the Federal Electric Comission (CFE, by its Spanish acronym). It is located at the eastern edge of the Trans Mexican Volcanic Belt (TMVB) forming the northern boundary of the Serdán-Oriental basin. The shallow subsurface has been studied extensively, but knowledge of the geothermal system at depths...
Deutsche Erdwärme GmbH & Co. KG is today the largest German private geothermal project developer and future operator in the German part of the Upper Rhine Graben area. The company currently holds ca. 1000 km² of granted project concession area in the two federal states of Baden Württemberg and Rhineland-Palatinate. Backed with strong financial support by public (or strategic) investors...
The primary goal of the present work is evaluation and comparison of vertical and horizontal well placements and their impact on the power output of a CPG (CO2 Plume Geothermal) system. Performances of vertical and horizontal wells arranged in a repeated five-spot pattern are evaluated for single- and multi-phase flow cases. Numerical models were developed in MOOSE (Multiphysics Object...
To achieve a low-carbon and sustainable future, the utilization of geothermal energy gains more attention all around the world, due to its sustainability, continuity and low carbon emissions. Avoiding the disequilibrium of ground temperature and large area requirement from application of traditional borehole heat exchanger (BHE, around 150 m), deep borehole heat exchanger (DBHE, down to 2500...
The Muschelkalk, composed of Triassic limestones, marls, dolomites, and evaporites, forms part of the Permo-Triassic cover of sedimentary rocks that directly overlies the fractured granitic reservoir used for geothermal energy exploitation in the Upper Rhine Graben. Petrophysical data for this lithostratigraphic unit are sparse, but are of value for reservoir prospection, stimulation, and...
Preexisting fractures may deform under the influence of changes in temperature or pressure during development and operation of a geothermal reservoir. Such deformation events are both of consequence in themselves, as they may be felt as earthquakes at the surface, and by virtue of the impact they may have on properties of the reservoir, such as the permeability. Using a discrete fracture...
In the frame of the EU Horizon 2020 DEEPEGS project and the IDDP2 project, the well RN-15 located in the Reykjanes geothermal field (Iceland) was deepened. So far, this well, namely RN-15/IDDP2 is the deepest geothermal well drilled in Iceland with a final depth of 4659 m and a measured bottom-hole temperature of 427°C and fluid pressure of 34 MPa. During drilling, several temperature logs...
The natural permeability of geothermal reservoirs is low and needs to be enhanced
to ensure an efficient use and economic viability. Next to chemical enhancement, the main technique used for that purpose is hydraulic fracturing. Here, hydraulic fracturing is introduced in a thermo-poroelastic framework. The main addition to this framework is a fracturing model, phrased in terms of Terzaghi's...
In the granitic basement of the Upper Rhine Graben (URG), fracture zones (FZs) are bearing the major permeability. The investigation of permeable hydrothermally altered FZs and their distribution in the well is a key issue for the understanding of fluid circulation in granitic rocks. Hence, it is crucial for the optimization of the fluid flow in existing geothermal wells and for the target of...
GEMex, a joint geothermal project of a European and Mexican consortium, began in late 2016 with the purpose to develop geothermal energy in the easternmost region of the Trans-Mexican Volcanic Belt. Los Humeros superhot geothermal area, commissioned to the Comisión Federal de Electricidad (CFE), was chosen as a test site for a superhot geothermal system. Extensive geological, geochemical, and...
The United Downs Deep Geothermal Power (UDDGP) project is the first geothermal power project in the United Kingdom. It aims to develop the geothermal resources in the heat-producing granites that lie beneath Cornwall in SW England. Financial support has come from the European Regional Development Fund and the local authority (Cornwall Council) who, together, have provided £13m of the £18m...
High-temperature geothermal fields are mostly associated with the occurrence of intrusive and/or extrusive magmatic centers. We present the results achieved in different National and European research projects, i.e. Geothermal Atlas of Southern Italy, Descramble and Gemex projects. We applied an integrated approach in order to set-up numerical models able to simulate the conductive-convective...
Drill core from the Tintina Trench was extracted near Ross River region, Yukon; Canada. The Tintina Trench is a late Miocene graben that was formed along the antecedent early Tertiary Tintina fault. The graben is a natural catchment for alluvial and glacial sediment. In 2018, the Yukon Geological Survey drilled a 500 m geothermal gradient well in the area. Core from the well was logged, and a...
In order to determine suitable locations for geothermal exploration, reliable predictions of the earth's subsurface temperature field are essential. For these predictions, it is necessary to consider the uncertainties of the involved parameters. However, with the current state-of-the-art simulations standard uncertainty quantification methods, such as Markov Chain Monte Carlo are...
Aluto-Langano geothermal field is located within the central southern portion of the Main Ethiopian Rift (Lake District), approximately 200 km southeast of Addis Ababa. Geothermal explorations began in the mid-1980s with the drilling of eight deep exploratory wells (maximum depth of 2500 m). The full potential of this field has not been fully exploited and therefore there is a need for further...
The Los Humeros geothermal system is an operating steam dominated field with 65 wells (23 producing). With 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.
For better reservoir...
The best way to study the subsurface geothermal potential is by directly measuring the heat flow and temperature from boreholes. However, heat flow and temperature data are not uniformly distributed and not consistently deep; thus they are not enough in inferring deep thermal distributions. In this case, Curie depth isotherm may provide the deep thermal distribution which cannot be obtained...
The geophysical characterization of reservoir properties, such as lithofacies, porosity and other petrophysical variables, is essential for the exploitation of subsurface reservoirs. Indeed, reservoir lithofacies classification provides significant information about the petrophysical behavior of reservoir rocks and their degree of compartmentalization (Bosch et al., 2002). Furthermore, the...
In a geothermal reservoir, seismicity may be induced due to pressure changes in the underground as a result of drilling, stimulation or circulation operations. The induced seismic events are therefore strongly linked to the fluid flow and the geological structures that make this fluid flow possible. The development of the deep geothermal site at Rittershoffen (Alsace, France) was monitored...
In order to meet the increasing worldwide energy demand in the next decades, access to deep geothermal, oil or gas reservoirs will be key in the future global energy supply. Construction of deep wells, especially for deep geothermal energy, require major costs, mainly related to the involved drilling operations. Indeed, drilling costs are found to increase exponentially with depth and,...
Logging while drilling (LWD) borehole images are widely used for the analysis of borehole breakouts. These breakouts develop when the circumferential stress around the borehole exceeds the compressive strength of the rock. Furthermore, they can show a temporal development. The aim of this thesis was the investigation whether a causal relationship between drilling operations and the development...
Predictive Mechanical model for fracture stimulation in an enhanced geothermal system (EGS) context
Keywords: GEMex, Enhanced Geothermal System (EGS), scanline survey, Discrete fracture model (DFM), Finite Element Method (FEM)
ABSTRACT
The development of an EGS is one of the goals of the GEMex project, an international collaboration of two consortia, one from Europe and one from Mexico. The...
The fluid flow in Enhanced Geothermal Systems (EGS) is dominated by hydraulically stimulated fractures and faults which are the key elements of their hydraulic performance and sustainability. At the fault scale, the flow performance is influenced by the aperture distribution which is strongly dependent on the fault roughness, the geological fault sealing, the relative shear displacement, and...
Germany defined an ambitious social and economic plan in order to cut 80 % of CO2 emissions by 2050. In this context, geothermal energy can play a key-role, since the high capacity factor and the possible heat and power configuration. Several power plants and district heating systems are currently running in Germany on geothermal sources.
In this work, an extended techno-economic analysis of...
In Germany, heating accounts for approximately two thirds of the end energy consumption in private households. It is estimated that by about 2060 the amount of energy used worldwide in cooling will overtake that used in heating. Therefore, there is a need to design efficient energy systems to supply heating and cooling loads simultaneously.
A cooling cycle cools a heat source by dissipating...
Geothermal power is one of the renewable energies which is extensively used in Italy, especially in Tuscan region, and which is becoming very discussed all around Europe. Geothermal energy exploits the geological heat sources, which are naturally present and it is considered as a renewable energy when the short time period is taken into account. However, the continuous exploitation of the...
Lithium (Li) is one of the crucial elements for the realization of electric mobility, energy transition and digitization, with rising demand and prices over the last decades. However, with an import rate of 86% (2010 – 2014) and a contribution to global Li-production of less than 1% (2017), Europe depends almost entirely on Li-import. To reduce the dependency, Li deposits and new and...
The Theistareykir geothermal field is located on the path of the Mid-Atlantic ridge in Northeastern Iceland. A power plant in the area produces 90 MWe since autumn 2017 using 13 production wells of around 2 km depth and 3 injection wells of about 450 and 100 m depth.
We monitor the spatial and temporal evolution of the geothermal reservoir using time-lapse magnetotellurics (MT) and...
In order to successfully demonstrate geothermal binary power plant technology at an Indonesian site and to intensify the know-how transfer in this technology field a German-Indonesian collaboration project has been initiated in 2013 involving GFZ Potsdam (Germany), the Agency for the Assessment and Application of Technology in Indonesia (BPPT) and PT Pertamina Geothermal Energy (PGE)....
Despite the main contribution that deep geothermal technologies bring to the energy transition from fossil to renewable resources in many European countries, in some regions these technologies are confronted with a negative perception, particularly in terms of environmental performance, which could seriously hamper their market uptake.
The evaluation and effective communication of...
In 2017, the energy delivered for heating purposes of buildings in the State of Geneva in Switzerland came from oil- and gas-fired boilers, which led to negative impacts on air pollution and global warming. The 2035 target of the State of Geneva is therefore to reduce the annual heat consumption to 29 GJ/capita, from which 34% should come from renewable energy or waste heat recovery. The State...
Ground source heat pump (GSHP) systems has become a renewable technology to provide space heating and cooling. An evident trend is the intensive exploration of shallow geothermal heat within a limited area, e.g. residential quarters. In such context, thermal interaction among nearby installations is often expected, which leads to concerns about the subsurface environment and the system...
In electricity grids, demand and generation must be balanced at all times. Modern electricity is primarily generated by constant power sources, such as nuclear and coal, and quickly dispatchable sources, such as gas fired power plants, which can be adjusted based on small demand variations. However, as anthropogenic total CO$_2$ emissions already make up almost 75% of the atmosphere's total...
Boreholes under dynamic conditions are a highly non-linear and complexly coupled thermo-hydraulic system. Multiple parameters, for instance, temperature, pressure, specific heat, enthalpy, viscosity, flow regime, heat transfer, degassing, steam quality and salinity are inter connected. Production and injection often entail several engineering challenges and operational problems, within the...
Reactive transport simulations help us better understand how geochemical reactions affect complex geothermal systems. However, geochemical reaction calculations can be extremely costly, sometimes accounting for over 99% of all computing costs in the simulation. As a result, the common practice is to simplify chemical details of fluids and rocks in the computer model to make it more...
Flow in fractured porous media is encountered in a broad spectrum of industrial, environmental, and engineering applications. This covers, for example, geothermal systems and hydraulic fracturing, carbon dioxide sequestration, management of karstic aquifers, and oil production. For those and other applications, modeling has become an indispensable tool for several purposes, such as...
A new subsurface mine water geothermal research facility, part of the UK Geoenergy Observatories, is being constructed in the Clyde Gateway area of Glasgow City, UK. The facility will enable scientists to take forward research that is vital to understanding the role and potential of abandoned mine systems as heat source/ sink, such as integration into district-wide heating/cooling networks,...
For a modular and comprehensive approach to characterization of reservoir properties such as temperature, pH or salinity, we present reporting nanoparticles with an architecture that forms a dual signal system in a core-shell structure. In this proof of concept example of thermo-reporting nanoparticles, the inner shell contains an inert signalling function, which enables the detection of the...
The development of an EGS is one of the goals of the GEMex project, an international collaboration of two consortia, one from Europe and one from Mexico. The research is based on exploration, characterization and assessment of two geothermal systems located in the Trans-Mexican volcanic belt, Los Humeros and Acoculco.
Los Humeros has been a producing field for several years, but Acoculco is...
Geothermal energy is classified as a renewable resource, where “renewable” describes a characteristic of the resource: the energy removed from the underground resource is continuously replaced by more energy on time scales similar to those required for energy removal and those typical of technological/societal systems. Consequently, geothermal exploitation is not a “mining” process. The...
The Los Humeros Volcanic Complex (LHVC) is an important geothermal target in Mexico, hosting a geothermal field currently producing ca. 95 MW of electric power. The geothermal field is located in a Quaternary collapse caldera where resurgence occurs since ca. 50 ka. The analysis of the LHVC structure and its influence on secondary permeability and occurrence of thermal anomalies is important...
