Analysis of Pressure/Flow Response Data from the EGS Collab Project
- M. D. Ingraham (Sandia National Laboratories) | H. A. Knox (Sandia National Laboratories) | C. E. Strickland (Pacific Northwest National Laboratory) | V. R. Vermeul (Pacific Northwest National Laboratory) | J. A. Burghardt (Pacific Northwest National Laboratory)
- Document ID
- American Rock Mechanics Association
- 53rd U.S. Rock Mechanics/Geomechanics Symposium, 23-26 June, New York City, New York
- Publication Date
- Document Type
- Conference Paper
- 2019. American Rock Mechanics Association
- 2 in the last 30 days
- 30 since 2007
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ABSTRACT: A series of fracture and flow tests are being performed at the Sanford Underground Research Facility (SURF) as part of the EGS Collab project. The tests involve generating a communicating fracture(s) between two boreholes, and monitoring flow through the generated fracture(s). A long-term flow test was performed at the end of October 2018 through early November of 2018 between the injection and production wells at the EGS Collab site on the 4850 Level of SURF. This paper will present an analysis of the pressure, and flow during this test. Analysis and interpretation of the variation in the efficiency of the connection as the injection conditions changed is presented. Recovery of injected fluid is between 70 and 85%. Injection conditions varied from constant pressure, to constant rate, with formation induced pressure rise at constant flow rate, and multiple flush cycles to induce pressure decrease from apparent fracture plugging.
The Engineered Geothermal Systems (EGS) Collab project is a multi-institution (comprised of national labs, universities and industry partners) Energy Efficiency and Renewable Energy (EERE) Department of Energy (DOE) project where efforts are underway to build a meso scale test bed for validation of theories and models of hydraulic stimulation and flow used in EGS systems. The testbed is located in an underground facility (Sanford Underground Research Facility, SURF) which allows for high stress regions, with short boreholes and relatively low cost operations. The goal of the project is to increase our understanding of the thermal-hydrological-mechanical-chemical response of the rock mass to engineered activities associated with EGS.
More detailed information on the EGS Collab project can be found on the DOE website under https://www.energy.gov/eere/geothermal/egs-collab
This paper documents the design and fabrication of the pressure systems used to perform the first field test at the SURF field site (Kneafsey et al., 2018).
EGS is a process that scientists have been trying to optimize since the first field test at Fenton Hill in 1970 by Los Alamos National Laboratory (Kelkar et al., 2016). The work since Fenton Hill falls into three general categories. First, injection of fluids at pressures above the minimum principal stress in order to induce tensile fractures in the rock (e.g., MIT, 2007; Brown et al., 2013). Second, injection of fluid at low to moderate pressures in order to generate slip on preexisting joints (e.g. Dorbath et al., 2009; McClure and Horne, 2014; Cladouhos et al., 2016). Finally, injection of water at low pressure, but with a large thermal gradient to induce thermal fracture (e.g. Braford et al., 2016; Rutqvist et al., 2016). Each of these methods has met with mixed success, the EGS Collab project has focused on the first method of stimulation to this point. However, there may have been some inadvertent slip generated on pre-existing fractures while attempting to generate new tensile fractures.
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