1,720,992 research outputs found
Understanding controls on temperature anomalies in the Wörth area of the Upper Rhine Graben by integrating static and dynamic data at the regional scale
No full textPressure transient analysis to investigate a coupled fracture corridor and a fault damage zone causing an early thermal breakthrough in the North Alpine Foreland Basin
No full textThe heterogeneity of the Upper Jurassic carbonate reservoir (Malm reservoir) beneath the North Alpine Foreland Basin has a significant influence on the mass and heat flow processes during geothermal exploitation. Geophysical borehole data revealed that sub-seismic scale fractures and karstified fractures occur at the inflow zones of deep geothermal wells. However, pressure transient analysis (PTA) in some previous studies concluded that it is difficult to detect the influence of sub-seismic scale features, suggesting that radial flow regime is dominant. Accordingly, a regional thermal-hydraulic model adopted the equivalent porous medium (EPM) approach, homogenizing the sub-seismic scale reservoir heterogeneities; however, unable to detect an early thermal breakthrough (ETB) in a geothermal doublet located SE of Munich. We apply PTA on three buildup tests belonging to that doublet following a deterministic approach to constrain the reservoir type by interpreting the pressure derivative (PD) plots constrained by geophysical and geological data. We derive the magnitudes of the reservoir hydraulic parameters by matching the PD plots with the selected interpretation models. We find that clustered fractures have a significant influence on the reservoir hydraulics, evidenced by trough-shaped curves in the PD plots. Linear flow regime interpreted from the interference test between the two wells indicates permeability anisotropy, which may have caused the ETB. Geophysical data interpretations indicate that these fractures correspond to a coupled fault damage zone and a fracture corridor. Finally, we present a fit-for-purpose 2D discrete fracture network model utilizing the PTA results to match our analytically calibrated model. Our study offers a potential hydraulic explanation to the cause of the ETB highlighting the importance of integrating multi-scale/disciplinary data sets to improve the reliability of dynamic reservoir models, based on which, economic-related decisions are made.Applied Geolog
3D-seismic channel–floodplain geomorphology of the Rhaetian Distributive Fluvial System in the North German Basin: an integrated workflow with machine learning for geothermal prospects
No full textParametric analysis of geothermal reservoir performance in Mesozoic sandstone formations within the North German Basin developed by multi-well systems
No full textAbstract In the context of the heat transition in Germany, the decarbonization of the heating and cooling industry via renewable energy sources requires the usage of comprehensive strategies and novel engineering solutions. With regard to district heating in urban areas, middle-deep geothermal resources offer a great potential which has not been fully utilized yet due to the required minimum temperature of district heating networks, leading to the additional employment of industrial and high-capacity-power heat pumps. However, the controlling factors on the optimal and sustainable development of those middle-deep geothermal resources are not fully elucidated yet. By evaluating numerical approaches against analytical model solutions, this work systematically analyzes the impact of reservoir quality and operational controlling factors on the performance of Mesozoic sandstone reservoirs in the North German Basin (NGB) targeted by multi-well arrangements. For the first time, we compare in a comprehensive manner previous analytical model results with our numerical findings to characterize more broadly the quantitative influence of different controlling factors on the thermal breakthrough occurrence time, the maximum cooling rate after the occurrence of the thermal breakthrough and the end production temperature. Moreover, we especially focus and illustrate the controls on the behavior of the production temperature after the thermal breakthrough has occurred and conduct a one-factor-at-a-time (OAT) parametric sweep analysis with regard to the thermal utilization time or life span of a geothermal facility. Based on our numerical results, we set up a ranking scheme showing the influence of varying controlling parameters on the considered performance parameters. One of the striking findings of our scenario analysis relates to the thermal breakthrough occurrence time, which is 17 ± 3% higher for a geothermal doublet array compared to a single doublet. Yet, the maximum cooling rate of the production temperature after the thermal breakthrough is higher for the array layout, depending on the number of neighboring injection wells. Our comprehensive numerical study, therefore, illustrates in detail the complex thermo-hydraulic interaction of geothermal doublet arrays, the controls on the defined thermal lifetime as well as the optimization possibilities of middle-deep geothermal resources.German Federal Ministry for Economic Affairs and Climate ActionLeibniz-Institut für Angewandte Geophysik http://dx.doi.org/10.13039/50110000411
Shallow Geothermal Potential in Germany: A Workflow for Harmonized Suitability Maps
No full textThe demand for geodata on shallow geothermal energy (SGE) in Germany is rising, driven by an energy transition
strategy that promotes tapping into this potentially unlimited sustainable resource. However, the inconsistent nationwide characterisation of SGE potential hinders its expansion and utilisation. This paper examines the challenges in assessing geothermal suitability across Germany and introduces a novel workflow for its nationwide harmonised representation through traffic light maps
Multiphase, decoupled faulting in the southern German Molasse Basin – evidence from 3-D seismic data
No full textA hydrotectonic model of a geothermal reservoir - A study in Lahendong, Indonesia
No full textIn this study tectonic structural features and their hydraulic characteristics of fault zones were integrated into a consistent hydrotectonic model of the Lahendong geothermal reservoir, Indonesia. Moreover, these elements were analysed with respect to their relevance for the operation of the geothermal power plant at initial conditions, i.e. before the start of operation. The complex tectonic setting with volcanic activity provides evidence for relevant structural and hydrogeological elements, such as fault zones, surface spring discharge and joints at different spatial scales. The study area is highly variable with respect to hydraulic properties and chemical composition of the fluids. It consists of two types of fluids. Acid brine water with a pH of around 3 and an electrical conductivity ranging between 462011 mu S/cm and 9700 p,S/cm is characteristic for the reservoir in the North with temperatures up to 274 C. A moderate pH between 4 and 7, an electrical conductivity in the range of 400-1730 mu S/cm and temperatures of up to 340 C characterise the southern study area. The Lahendong geothermal field is subdivided into two sub-reservoirs. Faults are less permeable perpendicular to the strike of the faults than parallel to the strike. The characteristics of the complex reservoir system could be explained by the combination of hydrotectonics and hydrogeological parameters. Understanding the permeability distribution along fault zones is crucial to investigate subsurface fluid pathways as well as to sustainably use the reservoir. A compartmentalisation of the reservoir was derived from a stress field analysis of the tectonic elements and from hydrogeological observations. The information on underground fluid flow is essential to understand the subsurface flow of geothermal fluids. Here, the permeability of structures is identified as the limiting factor. (C) 2014 Elsevier Ltd. All rights reserved.German Federal Ministry for Education and Research (BMBF) [03G0753A
Assessment and Public Reporting of Geothermal Resources in Germany: Review and Outlook
Full text linkAny geothermal resource assessment requires consistent and widely accepted terminology, methods, and reporting schemes that facilitate the comparison of geothermal resource estimates. This paper reviews common resource assessment methods, as well as reporting codes and terminology. Based on a rigorous analysis of the portrayed concepts and methods, it discusses the appropriateness of the existing reporting codes for sustainable utilization of geothermal resources in Germany. Since the last quantitative geothermal resource assessment in Germany was done 15 years ago, a revised report is overdue. Unlike fossil energy commodities, geothermal energy replenishes naturally and heat recuperation increases in created heat sinks. This replenishment process offers the opportunity for sustainable reservoir management in the case of moderate production rates or cyclic operation. Existing reporting codes, however, regard geothermal resources in a similar way to fossil resources or focus too much on field development rather than on the whole assessment process. In order to emphasize the renewability of geothermal energy, we propose the reporting of geothermal capacities (per doublet or per km2) instead of recoverable heat energy which depends very much on project lifetime and other factors. As a first step, a new classification scheme for geothermal resources and reserves is outlined
The interplay of Malm carbonate permeability, gravity-driven groundwater flow, and paleoclimate – implications for the geothermal field and potential in the Molasse Basin (southern Germany), a foreland-basin play
No full textAbstract
The Molasse Basin in Southern Germany is part of the North Alpine Foreland Basin and hosts the largest accumulation of deep geothermal production fields in Central Europe. Despite the vast development of geothermal energy utilization projects especially in the Munich metropolitan region, the evolution of and control factors on the natural geothermal field, more specifically the time-varying recharge and discharge governing groundwater and heat flow, are still debated. Within the Upper Jurassic (Malm) carbonate aquifer as the main geothermal reservoir in the Molasse Basin, temperature anomalies such as the Wasserburg Trough anomaly to the east of Munich and their underlying fluid and heat transport processes are yet poorly understood. We delineate the two end members of thermal–hydraulic regimes in the Molasse Basin by calculating two contrasting permeability scenarios of the heterogeneously karstified Malm carbonate aquifer along a model section through the Wasserburg Trough anomaly by means of two-dimensional numerical thermal-hydraulic modelling. We test the sensitivity of the thermal-hydraulic regime with regard to paleoclimate by computing the two Malm permeability scenarios both with a constant surface temperature of 9 °C and with the impact of paleo-temperature changes during the last 130 ka including the Würm Glaciation. Accordingly, we consider the hydraulic and thermal effects of periglacial conditions like permafrost formation and the impact of the numerous glacial advances onto the Molasse Basin. Thermal-hydraulic modelling reveals the effect of recurrent glacial periods on the subsurface targets of geothermal interest, which is minor compared to the effect of permeability-related, continuous gravity-driven groundwater flow as a major heat transport mechanism.Bundesministerium für Wirtschaft und Energie http://dx.doi.org/10.13039/501100006360Leibniz-Institut für Angewandte Geophysik (3464
The rock mass as the governing factor for successfully developing deep geothermal systems in Southern Germany
No full textAbstract In Southern Germany, geothermal wells target Upper Jurassic carbonates, formerly referred to as Malm, below the Northern Alpine Foreland Basin (NAFB). In the northern, shallower carbonates (3000 m depth), e.g., in the Munich area, hydrothermal systems prevail, and wells yield proper flow rates. Deeper carbonates (< 4000 m) towards the south indicate a petrothermal system due to a decline in porosity and permeability. Inexplicably, fractures only contribute poorly to larger flow rates. This sets the goal for the project Dolomitkluft to analyse the rock mass for options countering low flow rates in two geothermal wells at Geretsried, Bavaria. Therefore, 20 m drill cores from 4600 to 4715 m total vertical depth (TVD) depict the initial structure of the rock mass: the rock parameters, the discontinuity network, and the in situ stresses. Alternating homogeneous, micritic, strong, to inhomogeneous, porous, weak limestones and massive, crystalline dolostones define the stratigraphy. Five joint sets from the cores can be distinguished into the bedding, two paleo anti‐ and synthetic normal faults and two recent strike‐slip faults. The latter, in combination with core disking, allows exclusively a strike‐slip (SS) stress regime and delimits the ratio to at least SH : Sv : Sh = 1.7 : 1.0 : 0.7. According to the results, including dilatation‐ and slip‐tendencies, drill trajectories of prosperous geothermal wells should head ESE/WNW, perpendicular to SS‐faults, and avoid the presence of normal faults.Abstract Das Gebirge als Schlüsselfaktor zur erfolgreichen Erschließung tiefer geothermischer Energie in Süddeutschland In Süddeutschland zielt tiefe Geothermie auf oberjurassische Karbonate (Malm) ab, die im Liegenden des Nordalpinen Vorlandbeckens (engl. NAFB) nach Süden abtauchen. Im nördlicheren NAFB, z. B. bei München, erbringen hydrothermale Systeme ertragreiche Schüttungen. Gegen Süden nehmen Porosität und Permeabilität in den tieferen Karbonaten (< 4000 m) ab. In dem petrothermalen System sind vorhandene Klüfte jedoch kaum hydraulisch konduktiv. Hier greift das Projekt Dolomitkluft an, das mithilfe der zwei Geothermiebohrungen bei Geretsried das Gebirge untersucht und Wege erörtert, höhere Schüttungsraten zu erreichen. Dazu dienen u. a. 20 m Bohrkerne aus einer Tiefe von 4600 bis 4715 m TVD, welche die natürliche Beschaffenheit des Gebirges, die Gesteinsparameter, das Kluftnetzwerk und Spannungsverhältnisse aufzeigen. Stratigraphisch zeigen die Kerne eine Wechsellagerung aus variierend festen, geschichteten Kalksteinen und massigen, kristallinen Dolomitsteinen, vergleichbar mit Karbonaten aus Oberflächenaufschlüssen. Fünf Trennflächenscharen in den Kernen repräsentieren die Schichtung, zwei Abschiebungs‐ und zwei aktive Blattverschiebungskluftsysteme (BV). Letztere lassen, in Kombination mit auftretendem „Core Disking”, nur ein BV‐Regime mit einem Mindestverhältnis von SH : Sv : Sh = 1.7 : 1.0 : 0.7 zu. Die gewonnenen Informationen, zzgl. Dilatation‐ und Scher‐Tendenzen, legen nahe, dass zukünftige Bohrungen in Richtung ESE/WNW, also senkrecht auf BV‐Störungen, abgeteuft und die Nähe zu Abschiebungen gemieden werden sollten
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