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Hochauflösende seismo-thermo-hydromechanische Analyse der hydraulischen Stimulation: Modellentwicklung, Validierung und Anwendung

Enhanced Geothermal Systems (EGS) zielen darauf ab, die in der Erdkruste gespeicherte Wärme durch zirkulierende Flüssigkeiten zwischen Injektions- und Produktionsbohrlöchern zu extrahieren. Ideale Bedingungen finden sich typischerweise in Formationen in einer Tiefe von 2 bis 5 km, in denen die Durchflussrate für kommerzielle geothermische Anlagen nicht ausreicht und in denen die Temperaturen hoch sind (d. H. >> 100 ° C). Daher ist die Hochdruck-Flüssigkeitsinjektion, die als hydraulische Stimulation bekannt ist, eine allgemein angewandte Technik, um ein verbundenes Bruchnetzwerk zu erzeugen, das die Flüssigkeitszirkulation erleichtert. Die hydraulische Stimulation geht typischerweise mit einer induzierten Seismizität einher, die von der Öffentlichkeit wahrgenommen werden kann und sogar Schäden verursacht. Das Ziel dieses Projekts ist es, ein grundlegendes Verständnis der induzierten Seismizität in gebrochenen Gesteinen zu vermitteln, das die Fähigkeit verbessert, das seismische Risiko vorherzusagen und zu kontrollieren. Dieses Projekt geht von der Hypothese aus, dass die Seismizität gemeinsam durch die Bruchnetzgeometrie und die aktivierten thermo-hydromechanischen (THM) Prozesse in geologischen Systemen gesteuert wird. Wir werden Discrete Fracture Networks (DFN) anwenden, um die strukturellen Diskontinuitäten darzustellen und die THM-Prozesse mit hoher Auflösung zu modellieren. Dieses Projekt verwendet die Datensätze aus kleinen (Dekameter-) Stimulationsexperimenten am Grimsel-Teststandort in der Schweiz und modernste numerische Modelle, um Folgendes zu erreichen: 1) Testen Sie die Wirksamkeit hochauflösender Modelle zur Erfassung der seismische, hydraulische und mechanische Prozesse, die mit kleinen Experimenten beobachtet wurden; 2) Verknüpfung der geometrischen Attribute eines Bruchnetzwerks (wie Intensität, Konnektivität, Länge und räumliche Verteilung) mit der räumlichen, zeitlichen und Größenverteilung der induzierten Seismizität; 3) ein neuartiges Prognosemodell für die maximal mögliche Größe vorschlagen und testen, das die gemeinsamen Auswirkungen von Multiphysikprozessen berücksichtigt, die unter standortspezifischen geologischen Bedingungen und Betriebsbedingungen dominieren; 4) Bewertung der Hochskalierung der hochauflösenden DFN-Modelle im kleinen Maßstab (Dekameter), um die Experimente im Reservoir-Maßstab (Kilometer) zu simulieren. Dieses Forschungsprojekt ist neu in der Behandlung der durch Injektion induzierten Seismizität durch hochauflösende physikbasierte Modelle und hochwertige Datensätze, die aus einzigartigen In-situ-Experimenten abgeleitet wurden. Die vorgeschlagene Forschung hat erhebliche Auswirkungen auf die Förderung der Übergangspolitik hin zu einer Versorgung mit erneuerbaren Energien und trägt dazu bei, unser Wissen über die Auslösemechanismen induzierter Erdbeben zu erweitern.

Synthese numerischer Modellansätze für Reservoirbehandlungen in verbesserten geothermischen Systemen, Vorhaben: Partikelbasierte Modelle zur Simulation von Enhanced Geothermal Systems

Synthese numerischer Modellansätze für Reservoirbehandlungen in verbesserten geothermischen Systemen, Vorhaben: Bohrlochversuche im Bedretto-Untertagelabor zur Skalenabhängigkeit hydromechanischer Gesteinseigenschaften

3D DAS-VSP data from the Groß Schönebeck site, Germany, February 2017

An extensive vertical seismic profiling (VSP) survey using wireline distributed acoustic sensing (DAS) technology was carried out between the 15th and 18th of February 2017 at the geothermal in-situ laboratory Groß Schönebeck, Germany. Borehole measurements were recorded in two 4.3 km deep wells E GrSk 3/90 and Gt GrSk 4/05. Two hybrid fibre optics cables were freely lowered inside the wells to form dense receiver arrays. As a seismic source, four heavy vibroseis trucks were used. The survey consisted of 61 source positions distributed in a spiral pattern around the target area. This data publication consists of raw uncorrelated seismic data acquired for 3D seismic imaging purposes. Supplementary information such as well trajectories, source point coordinates, and the pilot sweep data is also provided. Data related to zero-offset measurements can be found in Henninges et al. (2021, https://doi.org/10.5880/GFZ.4.8.2021.001). Further details on the survey design and data acquisition parameters can be found in Henninges et al. (2021, https://doi.org/10.5194/se-12-521-2021); Martuganova et al. (2021, 2022). Information on high-resolution 3D reflection seismic acquisition campaign carried out at Groß Schönebeck in February–March 2017 can be found in Krawczyk et al. (2019); Bauer et al. (2020); Norden et al. (2022). The 3D DAS VSP processing workflow, 3D DAS imaging results, and comparison with 3D surface seismics are presented in Martuganova et al. (2022).

Gebirgsspannungsprofil in Enhanced Geothermal Systems (EGS) - Spannungsprofilierung in EGS

Earthquake catalog of induced seismicity recorded during and after stimulation of Enhanced Geothermal System in Helsinki, Finland

The dataset is supplementary material to the Solid Earth research article of Leonhardt et al. (2021). The dataset is a high-resolution catalog of seismicity framing the stimulation campaign of a 6.1 km deep Enhanced Geothermal System (EGS) in Helsinki suburban area, Finland. Within the St1 Deep Heat project, a total of 18,160 m3 of fresh water was injected into crystalline rocks during 49 days in summer 2018. The seismicity was monitored by a 12-level seismometer array at >2km depth and a seismic network of near-surface borehole sensors surrounding the EGS site. We expanded and refined the original catalog of Kwiatek et al. (2019) including detected seismic events and earthquakes that occurred two month after the end of injection and determining new locations and relocations on the basis of a new velocity model derived from a post-stimulation vertical seismic profiling campaign. A detailed description of the catalog reprocessing as well as a description of basic statistical and spatio-temporal properties of the catalog can be find in the data description file. Definition of columns in the data table (also in the header of the data): event ID, event class, datenumber [integer part = day since year 0], year, month, day, hour, minute, seconds, local magnitude MLHEL, moment magnitude MW, absolute location in local cartesian coordinates [easting (m), northing (m), altitude (m)], relocated location in local cartesian coordinates [easting (m), northing (m), altitude (m)], fault plane solutions of estimated focal mechnisms [strike (°), dip (°), rake(°)] and root mean square fault plane uncertainty of estimated focal mechanisms.

Seismic moment and injection efficiency evolution during Enhanced Geothermal System (EGS) projects

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Source parameters of relocated earthquakes recorded during hydraulic stimulation within St1 Deep Heat project in Espoo, Finland

The dataset is supplementary material to Kwiatek et al. (2019, Science Advances). The dataset is a refined seismic catalog acquired during the hydraulic stimulation of the future geothermal sites located in Espoo, Finland. There, the injection well, OTN-3, was drilled down to 6.1 km-depth into Precambrian crystalline rocks. Well OTN-3 was deviated 45° from vertical and an open hole section at the bottom was divided into several injection intervals. A total of 18,159 m3 of fresh water was pumped into crystal-line rocks during 49 days in June- and July, 2018. The stimulation was monitored in near-real time using (1) a 12-level seismometer array at 2.20-2.65 km depth in an observation well located ~10 m from OTN3 and (2) a 12-station network installed in 0.3-1.15 km deep bore-holes surrounding the project site. On completion of stimulation it the catalog contained 8452 event detections overall, and 6152 confirmed earthquakes located in the vicinity of the project site (epicentral distance from the well head of OTN-3 <5 km). These were recorded in a time period lasting 59 days: 49 days of active stimulation campaign and the 10 days following completion. The initial industrial seismic catalog of 6150 earthquakes was manually reprocessed. The P- and S-wave arrivals of larger seismic events with M>0.5 were all manually verified, and, if necessary, refined. Earthquakes with sufficient number of phases and seemingly anomalous hypocenter depths (e.g. very shallow or very deep) were manually revised as well. The hypocenter locations were calculated using the Equivalent differential time method and optimized with an Adaptive Simulated Annealing algorithm. The updated catalog contained 4,580 earthquakes that occurred at hypocenter depths 4.5-7.0 km, in the vicinity of the stimulation section of OTN-3. To increase the precision of their locations, the selected 2155 earthquakes with at least 10 P-wave and 4 S-wave picks were relocated using the double-difference relocation technique. The relocation uncertainties were estimated using bootstrap resampling technique. The relocation reduced the relative precision of hypocenter determination to approx. 66 m and 27 m for 95% and 68% of relocated earthquakes. The final relocated catalog that constitutes the here published contained 1,977 earthquakes (91% of the originally selected events).

A 100 3-component sensor deployment to monitor the 2018 EGS stimulation in Espoo/Helsinki, southern Finland - Datasets

A seismic network was installed in the Helsinki capital area of Finland to monitor the response to a 6 km deep geothermal stimulation experiment in 2018. The Institute of Seismology, University of Helsinki (ISUH), installed these 100 geophones in addition to five surface broadband sensors and a 13-site borehole network deployed by the operating company. The stations operated for 106 days between 7 May and 20 August 2018 (day 127 to 232). The data set consists of raw CUBE-recorder data and converted MSEED data.

DAS-VSP Data from the Feb. 2017 Survey at the Groß Schönebeck Site, Germany

This data publication contains vertical seismic profiling (VSP) data collected at the Groß Schönebeck site, Germany, from February 15-18, 2017. Energy excitation was performed with vibrator sources. Data was acquired in the two4.3 km deep wells E GrSk3/90 and Gt GrSk4/05 (in the following referred to as GrSk3 and GrSk4) using hybrid wireline fiber-optic sensor cables and distributed acoustic sensing (DAS) technology. In total, data for 61 source positions (VP1-VP76) distributed in a spiral-shaped pattern with offsets between 180 m and 2000 m from the wellheads was collected. The data publication covers selected common source gathers for a zero-offset position and representative examples for three intermediate-and far-offset positions, in the form of full waveform data stored in SEG-Yformat. Both uncorrelated raw data and data for different processing stages described in Henninges et al. (2021)are given. Moreover, the survey geometry data (well trajectories and source point coordinates), the pilot sweep data, records of a conventional three-component borehole geophone, and processing results for the VP10 zero-offset position (vertical one-way travel times, interval velocities, corridor stacks) are included. Further information on the survey design and data acquisition, the overall characteristics of the acquired data, and the zero-offset data processing and evaluation for the VP10 source position are described in Henninges et al. (2021)

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