The EGS Collab project is developing ~10-20 m-scale field sites where fracture stimulation and flow models can be validated against controlled, small-scale, in-situ experiments. The first multi-well experimental site was established at the 4850 level in the Homestake Mine in Lead, South Dakota, where hydraulic fractures were created at an injection well drilled sub-horizontal from the drift. This file contains the second set of tracer data (also include the data uploaded previously, https://gdr.openei.org/submissions/1128) for the EGS Collab testbed. The tracer tests were conducted during October 2018 - November 2019. Injected tracers include DNA, C-dots (fluorescein nano particles), fluorescein, rhodamine-b, sodium chloride, lithium bromide and cesium iodine. The tracers have been detected in three flowing wells located about 7.5 to 9 meters away from the injection interval. The tracer breakthrough curves from these locations have been adjusted to account for the residence time in the injection and production tubing. The details about the tracer test can be found in Background and Methods of Tracer Tests (Mattson et al. (2019,a,b)) (also included in this package). References Mattson, E.D., Neupane, G., Plummer, M.A., Hawkins, A., Zhang, Y. and the EGS Collab Team 2019a. Preliminary Collab fracture characterization results from flow and tracer testing efforts. In Proceedings 44th Workshop on Geothermal Reservoir Engineering, edited, Stanford University, Stanford, California. Mattson, E.D., Neupane, G., Hawkins, A., Burghardt, J., Ingraham, M., Plummer, M., and the EGS Collab Team, 2019b. Fracture tracer injection response to pressure perturbations at an injection well. GRC Transactions, Vol. 43, 2019. Neupane, Ghanashyam, Earl Mattson, Adam Hawkins, Mitchell Plummer, and Yuran Zhang. EGS Collab Testbed 1: Tracer data sets. No. 1128. DOE Geothermal Data Repository; Idaho National Laboratory, 2019.

This paper documents our effort to use a fully coupled hydro-geomechanical numerical test bed to study using low hydraulic pressure to stimulate geothermal reservoirs with existing fracture network. In this low pressure stimulation strategy, fluid pressure is lower than the minimum in situ compressive stress, so the fractures are not completely open but permeability improvement can be achieved through shear dilation. We found that in this low pressure regime, the coupling between the fluid phase and the rock solid phase becomes very simple, and the numerical model can achieve a low computational cost. Using this modified model, we study the behavior of a single fracture and a random fracture network.

The EGS Collab SIGMA-V project is a multi-lab and university collaborative research project that is being undertaken at the Sanford Underground Research Facility (SURF) in South Dakota. The project consists of studying stimulation, fluid-flow, and heat transfer processes at a scale of 10-20 m, which is readily amenable to detailed characterization and monitoring. One objective of the project is to establish circulation from injector to producer by hydraulically fracturing the injector. Data generated during these experiments is to be compared with predictions from coupled thermal, hydrological, mechanical, and chemical simulators. One such a simulator, TOUGH2-CSM, has been enhanced in order to simulate EGS Collab SIGMA-V project experiments. These modifications include adding tracers, the capability to model tracer sorption, and an embedded fracture formulation. A set of example problems validate our conservative tracer transport and sorption formulations. We then simulated tracer transport and thermal breakthrough for the first EGS Collab SIGMA-V experiment. This dataset includes the TOUGH2-CSM input and output files associated with the thermal and tracer simulations. A conference paper is included for additional context.

Numerical modeling on fused silica cylindrical materials for predicting overpressures required to fracture an homogeneous pure (surrogate) material with known mechanical properties similar to igneous rock materials and later compare these values to experimental overpressures obtained in actual fused silica samples at PNNL's lab-scale stimulation system.

This dataset contains experimental measurements of fluid flow and pressure behavior during fracture conductivity tests in granite core samples. The tests were designed to evaluate various ionic and nonionic fluids, including BMiMBr, HPyBF4, HPyBr, an oil-based fluid (OBF-1), and a water-based fluid (WBF-2), under different temperature and pressure conditions relevant to geothermal systems. Data were collected at injection pressures ranging from 500 to 800 psi and temperatures from room temperature up to 80 C. Each file includes multiple sheets organized by fluid type and temperature, containing time-series measurements of pump pressures, flow rates, and volumes for confining, water injection, and intermediate fluid circuits.

Laboratory slide-hold-slide tests were conducted in a conventional triaxial deformation configuration on 3/4-inch diameter cylindrical cores of Eureka quartzite bisected by a sawcut oriented at 30 degrees from vertical. Tests were conducted at constant normal stresses of 30, 110, and 210 MPa with a 10 MPa pore fluid pressure. The pore fluid was deionized water. Experiments were conducted at temperatures of 22, 100, and 200 degC.

Stimulation data from Experiment 1 of EGS Collab, which occurred on the 4850 ft level of the Sanford Underground Research Facility (SURF). A detailed description of the stimulation data is provided in the StimulationDataNotes.docx and is also available on the EGS Collab Wiki. A Meta Data Cheat Sheet, which describes all of the channels in the Raw CSV files, is available as well. Note that this cheat sheet is a comprehensive meta data descriptor and channels were added as the experiment evolved. This means that some columns may not be populated in early data. Additionally, we have included the chat logs from these experiments. The experiments were broadcast over teleconferencing software and real-time data displays were available to remote observers. The logs contain important observations from those personnel performing the experiment and the remote contributors. Finally, we have included summary and individual plots of all of the data for the user to compare to.

Stimulation data from Experiment 1 of EGS Collab, which occurred on the 4850 ft level of the Sanford Underground Research Facility (SURF). A detailed description of the stimulation data is provided in the StimulationDataNotes.docx and is also available on the EGS Collab Wiki. A Meta Data Cheat Sheet, which describes all of the channels in the Raw CSV files, is available as well. Note that this cheat sheet is a comprehensive meta data descriptor and channels were added as the experiment evolved. This means that some columns may not be populated in early data. Additionally, we have included the chat logs from these experiments. The experiments were broadcast over teleconferencing software and real-time data displays were available to remote observers. The logs contain important observations from those personnel performing the experiment and the remote contributors. Finally, we have included summary and individual plots of all of the data for the user to compare to.

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.