The EGS Collab Hydrofracture Experiment at the Sanford Underground Research Facility - Campaign Cross-Borehole Seismic Characterization
Abstract
An Enhanced Geothermal System (EGS) allows for the generation of electricity using the Earth's heat by improving (i.e., 'enhancing' or 'stimulating') the fracture permeability of rock and flowing fluid through the optimized medium. The complex behavior of EGS fracture systems and heat flow processes are being studied at various scales to determine the practical capabilities of EGS technology. The EGS collaborative (Collab) project is focused on experimentation of intermediate-scale (i.e 10's of meters) EGS reservoir generation processes and model validation at crystalline rock sites. A key phase of the project involves seismic characterization of a rock mass intended to be representative of EGS reservoir rock. A suite of boreholes was drilled from inside a mine drift on the 4850-foot ( 1.5 km) level of the Sanford Underground Research Facility (SURF) in Lead, South Dakota. The boreholes, comprised of one stimulation (injection) well, one production (extraction) well, and six monitoring wells, were each nominally drilled approximately 200 feet ( 60 meters) deep into the surrounding crystalline rock formation. Active source seismic data were collected using an electrical sparker source and an electro-mechanical impulse source to generate compressional (P-) wave and shear (S-) wave energy, respectively, at varying depths in the stimulation well. Seismic receivers were deployed in the sub-parallel production well, in addition to receivers installed in the monitoring wells, to detect P- and S-wave arrivals. These data and their associated 3D P- and S-wave velocity models of the rock mass are presented here with a discussion on seismic acquisition in horizontal boreholes in hard rock environments. These velocity models are critical to constraining the elastic parameters used for modeling and monitoring seismic hypocenters that are associated with fracture propagation during EGS stimulation activities.
Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.H11Q1689L
- Keywords:
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- 0915 Downhole methods;
- EXPLORATION GEOPHYSICSDE: 1822 Geomechanics;
- HYDROLOGYDE: 3616 Hydrothermal systems;
- MINERALOGY AND PETROLOGYDE: 8135 Hydrothermal systems;
- TECTONOPHYSICS