Explorationsstrategie tiefer geothermischer Ressourcen am Beispiel des süddeutschen Oberjuras (Malm)

Steiner, U.; Savvatis, Alexandros; Böhm, Franz; Schubert, Achim

doi:10.1007/978-3-642-54511-5_13

Cited by 8 publications

(7 citation statements)

References 23 publications

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“…Due to its relatively high temperature and promising hydraulic conditions, the Upper Jurassic Malm aquifer buried within the Molasse Basin is the main target formation for geothermal (hydrothermal) exploration in South Germany (Steiner et al 2014). The Molasse Basin, extending along the northern flank of the Alps as far north as the Franconian Alb, represents an alpine foreland basin (Fig.…”

Section: Introductionmentioning

confidence: 99%

Porosity–permeability relationship derived from Upper Jurassic carbonate rock cores to assess the regional hydraulic matrix properties of the Malm reservoir in the South German Molasse Basin

Bohnsack¹,

Potten²,

Pfrang³

et al. 2020

Geotherm Energy

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For the successful realization and productivity prediction of new hydrothermal projects in the South German Molasse Basin, the hydraulic matrix properties of the Upper Jurassic Malm reservoir have to be determined as accurately as possible. To obtain specific information on the distribution of the petrophysical parameters (e.g., rock density, porosity, and permeability) 363 samples of rare drilling cores from the reservoir northeast of Munich (wells Moosburg SC4 and Dingolfing FB) were investigated using different experimental methods. Additionally, porosity was calculated by a downhole resistivity log of a nearby borehole close to Munich for comparison and the attempt of transferability of the data set to other locations within the Central Molasse Basin. Core data were divided into groups of different stratigraphic and petrographic units to cover the heterogeneity of the carbonate aquifer and provide data ranges to improve reservoir and prediction models. Data for effective porosity show a high variance from 0.3 to 19.2% throughout this heterogeneous aquifer. Permeability measured on core samples is scattered over several orders of magnitude (10 −4-10 2 mD). Permeability models based on the porosity-permeability relationship were used to estimate permeability for the whole aquifer section and identify possible flow zones. A newly developed empirical model based on distinct lithofacies types allows a permeability estimation with a deviation < 10 mD. However, fractured, karstified, and vuggy zones occurring in this typically karstified, fractured, and porous reservoir cannot yet be taken into account by the model and result in an underestimation of permeability on reservoir scale. Overall, the dominant permeability trends can be mapped well using this model. For the regional transfer and the correlation of the results, a core-related porosity/ permeability log for the reservoir was compiled for a well close to Munich showing similarities to the core investigations. The validation of the regional transferability of the parameter set to other locations in the Molasse Basin was carried out by correlation with the interpreted log data of a well near Munich.

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Section: Introductionmentioning

confidence: 99%

Porosity–permeability relationship derived from Upper Jurassic carbonate rock cores to assess the regional hydraulic matrix properties of the Malm reservoir in the South German Molasse Basin

Bohnsack¹,

Potten²,

Pfrang³

et al. 2020

Geotherm Energy

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“…They are also of great relevance for an improved understanding of diagenetic pathways and hydraulic properties of the Permo-Triassic clastics and Late Jurassic carbonate rocks in the Franconian Alb. The latter serve as an important outcrop analogue for the most important deep geothermal (Malm) aquifer in the North Alpine Foreland Basin (Kröner et al, 2017;Mraz et al, 2018), whose petrophysical properties are known to strongly depend on burial depth (Bohnsack et al, 2020(Bohnsack et al, , 2021Homuth et al, 2014;Steiner et al, 2014). Finally, the integration of different parameters and measurement types provides an important reference dataset (Table A2) for future studies, aiming to use petrophysical properties of exhumed and near-surface located mudstones for burial history studies.…”

Section: Study Aimmentioning

confidence: 99%

Reconstructing post-Jurassic overburden in central Europe: new insights from mudstone compaction and thermal history analyses of the Franconian Alb, SE Germany

et al. 2022

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Abstract. The Franconian Alb of SE Germany is characterized by large-scale exposures of Jurassic shallow marine limestones and dolostones, which are frequently considered to be outcrop analogues for deep geothermal reservoir rocks in the North Alpine Foreland Basin farther south. However, the burial history of the Franconian Alb Jurassic strata is not well known as they were affected by emersion, leading to extensive erosion and karstification with only remnants of the original Cretaceous and Cenozoic cover rocks preserved. To estimate the original thicknesses of the post-Jurassic overburden we investigated the petrophysical properties and the thermal history of Lower and Middle Jurassic mudstones to constrain their burial history in the Franconian Alb area. We measured mudstone porosities, densities, and maturities of organic material and collected interval velocities from seismic refraction and logging data in shallow mudstone-rich strata. Mudstone porosities and P-wave velocities vertical to bedding were then related to a normal compaction trend that was calibrated on stratigraphic equivalent units in the North Alpine Foreland Basin. Our results suggest maximum burial depths of 900–1700 m, 300–1100 m of which is attributed to Cretaceous and younger sedimentary rocks overlying the Franconian Alb Jurassic units. Compared to previous considerations this implies a more widespread distribution and increased thicknesses of up to ∼900 m for Cretaceous and up to ∼200 m for Cenozoic units in SE Germany. Maximum overburden is critical to understand mechanical and diagenetical compaction of the dolostones and limestones of the Upper Jurassic of the Franconian Alb. The results of this study therefore help to better correlate the deep geothermal reservoir properties of the Upper Jurassic from outcrop to reservoir conditions below the North Alpine Foreland Basin. Here, the Upper Jurassic geothermal reservoir can be found at depths of up to 5000 m.

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“…Since about two decades, the Upper Jurassic carbonates of the Bavarian Molasse Basin in Southern Germany are the target for geothermal exploration as they provide favorable geological conditions for hydro-geothermal projects (Steiner et al 2014). The sedimentary layers of the aquifer partly show very good hydraulic properties, providing hot water with temperatures up to > 160 °C (Weber et al 2019).…”

Section: Description Of the Study Site Conditions And Wellsmentioning

confidence: 99%

Monitoring cold water injections for reservoir characterization using a permanent fiber optic installation in a geothermal production well in the Southern German Molasse Basin

et al. 2021

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Fiber optic sensing has gained importance for wellbore monitoring and reservoir characterization in geothermal fields as it allows continuous, spatially highly resolved measurements. Distributed acoustic sensing (DAS) and distributed temperature sensing (DTS) technologies, among others, enable monitoring of flow regimes and heat transport inside the wellbore to describe the dynamical behavior of the reservoir. The technically challenging installation of a permanent fiber optic monitoring system in a geothermal production well over the entire wellbore length was conducted for the first time at the geothermal site Schäftlarnstraße in Munich, Germany. One cable with two DAS fibers, two DTS fibers, and one fiber for a downhole fiber optic pressure/temperature gauge were clamped to ¾-in. sucker rods and installed to 3.7 km measured depth to collect data from the wellbore after drilling, during testing, and during operations. We present DTS profiles during 3 months of well shut-in and show the results of two cold water injection tests conducted to localize inflow zones in the reservoir and to test the performance of the fiber optic setup. A vertical displacement in temperature peaks of approximately 1.5 m was observed during the injection tests, presumably resulting from thermal contraction of the sucker rod–cable setup. This was verified by analyzing the strain information from the DAS records over 1 h of warm-back after cold water injection with the calculated theoretical thermal contraction of DTS of the same period. We further verified the flowmeter measurements with a gradient velocity analysis of DTS profiles during injection. Intake to the major inflow zone was estimated to 93.5% for the first injection test, respective 94.0% for the second, intake of flowmeter was calculated to 92.0% for the same zone. Those values are confirmed by analyzing DTS profiles during the warm-back period after the well was shut.

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Explorationsstrategie tiefer geothermischer Ressourcen am Beispiel des süddeutschen Oberjuras (Malm)

Cited by 8 publications

References 23 publications

Porosity–permeability relationship derived from Upper Jurassic carbonate rock cores to assess the regional hydraulic matrix properties of the Malm reservoir in the South German Molasse Basin

Porosity–permeability relationship derived from Upper Jurassic carbonate rock cores to assess the regional hydraulic matrix properties of the Malm reservoir in the South German Molasse Basin

Reconstructing post-Jurassic overburden in central Europe: new insights from mudstone compaction and thermal history analyses of the Franconian Alb, SE Germany

Monitoring cold water injections for reservoir characterization using a permanent fiber optic installation in a geothermal production well in the Southern German Molasse Basin

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