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Fiber optic data while primary cementing - Distributed Temperature and Distributed Vibrational Energy from a Distributed Dynamic Strain Sensing

For the safe and sustainable use of deep geothermal wells, construction must proceed as intended. An integer well ensures that all fluids within the borehole are always under control. One of the most critical steps is the cementing of the casings. Despite extensive experience in the petroleum industry, challenges with well integrity are a worldwide phenomenon. One reason could be that conventional measurement methods can only verify the success of cementing once the cement job has been completed. In contrast, distributed fiber optic sensing methods can monitor the entire cementing process along the entire drilling path. This data set contains the results of the Distributed Temperature Sensing (DTS) and the derived product "vibrational energy" of a Distributed Dynamic Strain Sensing (DDSS or DAS) of the whole cementing process. We collected this data during the primary cementing of an injection well's 874m surface casing at the geothermal site Schäftlarnstr, Munich. We measured the cement placement and 24 hours of the early hydration. We obtained the data with a fiber optic cable permanently deployed behind the casing. The cable contained Multi-Mode fibers (for DTS) and Single-Mode fibers (for DAS). Table 1 in the data description document shows the units used and the key parameters of our measurement. In the first step, we allocated each channel to its depth in the borehole. We used a cold spray (for DTS) and a tap test (for DAS) to locate the entry to the borehole. To obtain the vibrational energy of the DAS data, we summarized the raw dynamic strain with a Root Mean Square (RMS) in a window of 60 seconds. We calculated the vibrational energy for a wide range of different frequency ranges (Butterworth bandpass). The data are provided in csv formats and further explained in the data description document. Acknowledgement: GFK-Monitor is funded by the Federal Ministry for Economic Affairs and Climate Action via the Project Management Jülich (PTJ) (funding code: 03EE4036, project duration: July 1, 2022 - June 30, 2025). The fiber optic infrastructure was provided by GAB (Geothermie Allianz Bayern): Funded by: Bayerisches Staatsministerium für Wissenschaft und Kunst (Hauptgebäude: Salvatorstraße 2, 80333 München).

Crosshole seismic data at ICDP site 5068_1

This seismic crosshole dataset was acquired in the context of the DOVE project (Drilling Overdeep-ened Alpine Valleys) at ICDP site 5068_1 (Tannwald Basin) to image the glacial sediments at sub-meter scale. It consists of the field data with geographical coordinates. The project aims to investigate the landscape evolution in the Alpine region by drilling overdeep-ened valleys and analyzing the cores (DOVE-Phase 1 Scientific Team, Schaller et al., 2023, Schuster et al., 2024). At site 5068_1 (Tannwald Basin), three boreholes were drilled to a depth of about 160 m depth, reaching the bedrock. Boreholes 5068_1_A and 5068_1_B were flush drilling and bore-hole 5068_1_C was cored. In 2022, the boreholes were used to perform high-resolution crosshole seismic measurements in order to image the glacial sediments at sub-meter scale. This dataset con-sists of the seismic field data with geographical coordinates and is subdivided by (1) the used source and receiver borehole equipment (P: sparker and 24-station hydrophone string, SV: vertically polarizing shear wave source and three-component geophone string with eight geophones, SH: horizontally polarizing shear wave source and three-component geophone string with eight geophones), (2) the respective borehole plane (BA, BC, and AC), and (3) the acquisition geometry (STRING, CIRCLE, LINE_BA, LINE_BC, LINE_AC). The surface seismic data (CIRCLE, LINE_BA, LINE_BC, LINE_AC) was recorded by three-component geophones. The seismic data is provided in SEGY Rev. 1.0 format together with geometry files in csv-format.

Fibre optic distributed dynamic strain array (GFZ-Landsvirkjun) at Theistareykir, North-east Iceland

The GFZ-Landsvirkjun Theistareykir Fibre array is located in the Theytareykir geothermal area, in North Iceland. It is collocated with arrays of broadband seismometers and gravity meters (see e.g., https://doi.org/10.1186/s40517-021-00208-w). The geometry of the fibre array is following the telecom network in the area, and was chosen to test the seismological capabilities of telecom cables in this geothermal environment. We connected an iDAS V2 interrogator from Silixa. The interrogator location is lat=65.898041, lon=-16.966274. The array starts N-S and after 1.5 km, turns towards the East, up to a local transmission antenna station for mobile phones. The length of the path is ~5 km. The length of the cable is actually more than 15 km, as other fibre instance is connected at the transmission antenna station.. Jumps were performed along the cable to geo-locate the channels. The exact location of the fibre can unfortunately not be disclosed. Original recordings at 1000 Hz were downsampled to 200 Hz using a software from INGV-OE (michele.prestifilippo@ingv.it) and are provided in an h5 format. We provide here the first fibre instance (5 km long). The data contain 1 h long recording intervals framing M>5 teleseismic earthquakes recorded in the frame of the global DAS month, an initiative to collaboratively record and share simultaneously recorded DAS data from all over the world (https://www.norsar.no/in-focus/global-das-monitoring-month-february-2023). DAS is an emerging technology increasingly used by seismologists to convert kilometer long optical fibers into seismic sensors.

Global DAS Month 2023, Teleseismic Event Recordings, Potsdam Fiber

The here referenced dataset provides eventbased Distributed Acoustic Sensing (DAS) recordings made with an approximately 22 km long dark telecommunication fiber lying in urban Potsdam and surroundings. For each of 164 M>=5 earthquakes occurring in February 2023 and listed by the USGS, one hour of data is provided starting with the event's origin time. Additionally, the whole day of February 14 is provided in hourly files. The data was recorded in the frame of the global DAS month, an initiative to collaboratively record and share simultaneously recorded DAS data from all over the world (https://www.norsar.no/in-focus/global-das-monitoring-month-february-2023). DAS is an emerging technology increasingly used by seismologists to convert kilometer long optical fibers into seismic sensors.

3D-NEA: Three-dimensional lithospheric-scale structural model of the North East Atlantic

The Northeast Atlantic (NEA) region has long been a subject of interest due to its complex geological history, particularly regarding the interaction between the Iceland plume and the lithospheric plates. In this data publication, we present a comprehensive three-dimensional structural and density model of the NEA crust and uppermost mantle, consolidating and integrating a wide range of previously fragmented data sets. Our model highlights the influence of the Iceland plume on the region's geological evolution, shedding light on the mechanisms that facilitated the continental breakup between Europe and Laurentia during the earliest Eocene period. The whole workflow and methods are described in Gomez Dacal et al. (2023) and its Supplementary Information.

Acoustic Emission and Seismic moment tensor catalogs associated with triaxial stick-slip experiments performed on Westerly Granite samples

The dataset contains source parameters of acoustic emission (AE) events recorded during triaxial friction (stick-slip) experiments performed on the Westerly Granite sample WgN05. In addition we provide raw waveform data of AE events recorded in triggered mode with a network of 16 AE sensors. Basic seismic catalog associated with the stick-slip experiment contains origin time, hypocentral location in local Cartesian coordinate system of the sample (with associated uncertainties), and AE-derived magnitude. In addition, for a subset of AEs we provide full moment tensors. This catalog include information on fault parameters (strike, dip and rake of the two nodal planes), percentage of isotropic, compensated linear vector dipole and double-couple components of the full moment tensor, P, T, B axes orientations in the coordinate system of the sample, uncertainty assessment, as well as the six independent moment tensor components. Finally, we provide a time series of axial stress values as presented in the Kwiatek et al. (2023) as well as the coordinates of the AE sensors. The catalog and parametric data is supplemented with the raw waveform recordings stored in HDF5 format from 16 acoustic emission sensors placed on the surface of the sample.

Ground motion data simulated for various rupture scenarios of magnitude 6.0 earthquake in Southern California

This dataset is supplementary material to "Detection limits and near-field ground motions of fast and slow earthquakes" by G. Kwiatek and Y. Ben-Zion published in Journal of Geophysical Research - Solid Earth.The dataset contains spatial variations of ground motions (peak ground velocities) expected from various rupture scenarios of magnitude M6 earthquake that occurs in Southern California area, United States. The performed calculations of ground motions are based on synthetic velocity seismograms calculated with Discrete Wavenumber Method assuming crustal seismic velocities and attenuation properties in Southern California. The selected rupture scenarios include slow- and fast propagating ruptures (varying rupture velocity), crack- and pulse-type rupture type (varying rise time) and different rupture directivities (circular-to-unilateral, circular-to-bilateral ruptures are considered). The dataset allows to reproduce Figures 7-8 and S3-S4 from the original manuscript.

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).

Ultrasonic transmission measurements from seven boreholes from the STIMTEC-X experiment, Reiche Zeche Mine, Freiberg (Saxony, Germany)

In 2020 and 2021 the STIMTEC-X hydraulic stimulation experiment was performed at ca.~130 m below surface at the Reiche Zeche underground research laboratory in Freiberg, Saxony/Germany. The project temporally followed the STIMTEC experiment at the same site and aimed at understanding the stress heterogeneity of the anisotropic and metamorphic gneiss rock mass. The STIMTEC-X experiment applied the hydraulic stimulation technique in several boreholes at the mine-scale. Complementary to the stimulations, there were active seismic ultrasonic transmission data acquired before the stimulations. We use a seismic monitoring network consisting of six single-component acoustic emission (AE) sensors (sensitivity 1-60 kHz), six hydrophone-like AE sensors (sensitivity 1-40 kHz) and four to twelve single-component Wilcoxon accelerometers (sensitivity 50 Hz-25 kHz). The AE sensors and remained stationary in sub-horizontal and upwards reaching boreholes, the accelerometers were mostly installed along the tunnel walls with one accelerometer in a shallow borehole in each tunnel, and the hydrophone-like AE sensors were installed in the down-going water filled boreholes, but repositioned for each measurement campaign (Figure 1). This data set of 120 active ultrasonic transmission (UT) measurements is supplementary to Boese et al. (2022, in review), which introduces some of the active measurement campaigns of the STIMTEC-X experiment in detail. The whole data set togetter with the “Ultrasonic transmission measurements from six boreholes from the STIMTEC experiment, Reiche Zeche Mine, Freiberg (Saxony, Germany)” [https://doi.org/10.5880/GFZ.4.2.2021.002] was used to evaluate performance measures such as sensitivity and frequency bandwith, coupling, placement and polarity of the hydrophone-like AE sensor compared to AE sensors. The active seismic data provided here are from seven boreholes (BH01, BH05, BH06, BH10, BH14, BH18, BH19) as shown in Figure 1. There are nine tables provided as metadata of which seven contain the STIMTEC-X sensor coordinates for each measurement campaign, the event information of all the 120 UT measurements and the UT picks. The UT measurements were recorded with a sampling rate of 1 MHz and results from an automatic stack of 1024 UT pulses generated by the ultrasonic transmitter and recorded by the STIMTEC-X sensors. The UT measurements are saved in binary file format (fsf file format). Fsf-files can be processed with FOCI software: https://www.induced.pl/software/foci. Each fsf file contains 32768 samples, which corresponds to 0.032768 seconds. All UT event files were manual inspected and phase arrivals identified. These are stored in the fsf-file header as well as in the table STIMTECX_UT_picks.csv.

Seismic waveforms of fluid-induced seismicity from the 2018 hydraulic stimulation campaign at the OTN-3 well, Helsinki, Finland

This data publication contains seismic waveform data of 507 earthquakes recorded during the St1 Deep Heat project in June and July 2018, where the 6.1 km deep OTN-3 well near Helsinki, Finland, was hydraulically stimulated over 49 days (Kwiatek et al., 2019). The waveforms were recorded on a surrounding seismic monitoring network consisting of 12 stations, deployed at epicentral distances between 0.6 to 8.2 km and at depths between 0.23 to 1.15 km. Each station consists of three-component, 4.5 Hz, Sunfull PSH geophones, sampling at 500 Hz. The 507 earthquakes analysed were chosen from the relocated event catalogue by Leonhardt et al. (2021a). The dataset is supplementary material to the Geophysical Research Letters research article of Holmgren et al. (2022), which applied the Empirical Green’s Function technique to examine microseismic rupture behaviour at the Helsinki site.

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