This package includes data and models that support hydraulic fracture stimulation and fluid circulation experiments in the Sanford Underground Research Facility (SURF). A paper by Schwering et al. (2020) describes the deterministic basis for developing a "common" discrete fracture network (CDFN) model of significant natural fractures in EGS Collab Testbed 1 on the 4850-Level of SURF. The ReadMe for this model shows drift, wells, scanlines, fracture data, interpreted fractures, and geophysical visualizations. There is also a summary of the data that was used in this experiment and includes results from reviewing core, televiewer (TV) logs, core-TV depth/feature registration, and from mapping weeps in the 4850-Level drift. The CDFN is intended to be a baseline model of the pre-stimulated testbed (though some observations from stimulation helped inform the model).

This package includes data and models that support hydraulic fracture stimulation and fluid circulation experiments in the Sanford Underground Research Facility (SURF). A paper by Schwering et al. (2020) describes the deterministic basis for developing a "common" discrete fracture network (CDFN) model of significant natural fractures in EGS Collab Testbed 1 on the 4850-Level of SURF. The ReadMe for this model shows drift, wells, scanlines, fracture data, interpreted fractures, and geophysical visualizations. There is also a summary of the data that was used in this experiment and includes results from reviewing core, televiewer (TV) logs, core-TV depth/feature registration, and from mapping weeps in the 4850-Level drift. The CDFN is intended to be a baseline model of the pre-stimulated testbed (though some observations from stimulation helped inform the model).

The EGS Collab is conducting experiments in hydraulic fracturing at a depth of 1.5 km in the Sanford Underground Research Facility (SURF) on the 4850 Level. A total of eight ~60m-long subhorizontal boreholes were drilled at that depth on the western rib of the West Access Drift. Six of these holes are used for geophysical monitoring, one is used for hydraulic fracturing and the remaining hole was designed as a production borehole. In addition to these eight boreholes, 4 5-m Jack leg boreholes were drilled for housing geophones. This submission package includes well head locations, total lengths of boreholes, their orientations (gyro data). The reported boreholes orientation data were primarily obtained with REFLEX GYRO (TM) survey right after the completion of each hole. Gyro based orientations were later verified and refined with the results of magnetic orientation survey. Well head locations were ascertained by Laser/Lider survey of the drift around the Testbed.

The EGS Collab Project performed a series of tests to increase the understanding the response of crystalline rock mass to stimulations and fluid circulation to efficiently implement enhanced geothermal systems (EGS) technologies. The EGS Collab team created two underground testbeds at the Sanford Underground Research Facility (SURF) in Lead SD at a depth of approximately 1.5 km (4850 level) and 1.25 km (4100 level) to examine hydraulic fracturing and hydraulic shearing, respectively. Experiment 2 was designed to examine hydraulic shearing and fluid flow in testbed 2 in amphibolite under a controlled set of stress and fracture conditions. This document summarizes the general geology, natural fractures, and conceptual model(s) of stimulated fracture networks in the testbed 2. The dataset package included here are input and output products associated with Earth Models for the EGS Collab Testbed 2. The earth model datasets are included in the whole package (project) in Leapfrog file format. Also, datasets are given in primary input file format (csv).

These data and test descriptions comprise a chilled circulation test conducted at the 164' fracture in the EGS Collab Experiment 1 testbed on the 4850 ft level of the Sanford Underground Research Facility. Descriptions of the meta data, design drawings for the flow testing system, and evaluation of the thermistor data are provided here. The test ran from April 2019 through early March of 2020, when testing was concluded at the experiment 1 site. These data are are complementary to the stimulation data provided in another submission which is linked below (i.e. stimulation at the 164' notch). More information about the test itself as well as the rationale and process of data processing is available on the EGS Collab Experiment 1 Long Term Circulation Test wiki page which is also linked below.

Characterizing the stimulation mode of a fracture is critical to assess the hydraulic efficiency and the seismic risk related to deep fluid manipulations. We have monitored the three-dimensional displacements of a fluid-driven fracture during water injections in a borehole at ~1.5 km depth in the crystalline rock of the Sanford Underground Research Facility (USA). The fracture initiates at 61% of the minimum horizontal stress by micro-shearing of the borehole on a foliation plane. As the fluid pressure increases further, borehole axial and radial displacements increase with injection time highlighting the opening and sliding of a new hydrofracture growing ~10 m away from the borehole, in accordance with the ambient normal stress regime and in alignment with the microseismicity. Our study reveals how fluid-driven fracture stimulation can be facilitated by a mixed-mode process controlled by the complex hydromechanical evolution of the growing fracture. The data presented in this submission refer to the SIMFIP measurements and analyses of the stimulation tests conducted on the 164 ft (50 m) notch of the Sanford Underground Research Facility (SURF), during the EGS-Collab test 1. In addition to the datafiles, there is the draft of a manuscript submitted to Geophysical Research Letters (GRL).

The U.S. Department of Energy's Enhanced Geothermal System (EGS) Collab project aims to improve our understanding of hydraulic stimulations in crystalline rock for enhanced geothermal energy production through execution of intensely monitored meso-scale experiments. The first experiment was performed at the 4850 ft level of the Sanford Underground Research Facility (SURF), approximately 1.5 km below the surface at Lead, South Dakota. The data reported here were collected by the continuous active-source seismic monitoring (CASSM) system (Ajo-Franklin et al., 2011). This system was permanently installed in the testbed and consisted of 17 piezoelectric sources that were recorded by 2-12 channel hydrophone arrays, 18 3-C accelerometers, and 4 3-C geophones at a Nyquist frequency of 24kHz. The source array was activated in a repeated sequence of shots (each source fired 16 times and stacked into resultant waveforms) for the duration of the experiment (April 25, 2018 - March 7, 2019) with few exceptions. Please see the attached documents describing the source / receiver geometry. The data are available in both seg2 (.dat extension) and segy (.sgy extension) format. Each segy file contains multiple seg2 files.

This is the full wireline geophysical datasets for characterization of the EGS Collab Experiment #1 testbed on the 4850 level. A metadata file is included within the dataset explaining the logs, fracture picks, etc. Eight boreholes were drilled for this testbed and each one was logged with north seeking gyro, optical televiewer, acoustic televiewer, fluid temperature conductivity, resistivity and gamma, and full waveform sonic. In these folders are the processed results as text, csv, and pdf files, along with the raw data which will need to be read using WellCAD software.

The EGS Collab experiment 2 was focused on testing shear stimulation techniques. Shear stimulation, in this case, means using hydraulic pressure to cause shear slip on preexisting fracture or fault planes such that the hydraulic conductivity of the fracture or fault increases. The concept is to create a percolating network of permeable fractures by enhancing the permeability of a primarily preexisting network of fractures. To test this concept the hydraulic pressures for experiment 2 were kept below the the estimated magnitude of the least compressive principal stress based on a set of stress measurements in nearby well TV4100. All tests for experiment 2 were performed by applying hydraulic pressure to well E2-TC. Subsequent stimulations in both E2-TC and E2-TU where the injection pressure was increased above the least compressive principal stress are considered part of experiment 3, which is documented separately. The data are organized in directories labeled by the depth range isolated between packers.

The EGS Collab experiment 2 was focused on testing shear stimulation techniques. Shear stimulation, in this case, means using hydraulic pressure to cause shear slip on preexisting fracture or fault planes such that the hydraulic conductivity of the fracture or fault increases. The concept is to create a percolating network of permeable fractures by enhancing the permeability of a primarily preexisting network of fractures. To test this concept the hydraulic pressures for experiment 2 were kept below the the estimated magnitude of the least compressive principal stress based on a set of stress measurements in nearby well TV4100. All tests for experiment 2 were performed by applying hydraulic pressure to well E2-TC. Subsequent stimulations in both E2-TC and E2-TU where the injection pressure was increased above the least compressive principal stress are considered part of experiment 3, which is documented separately. The data are organized in directories labeled by the depth range isolated between packers.