A series of hydrofractures were performed on the 4100 ft. level of the Sanford Underground Research Facility (SURF) to quantify the minimum principal stress and stress orientation. The motivation for this work was to determine the suitability of the site as a second testbed for the EGS Collab project and to inform the testbed design. EGS Collab is a meso-scale project where experiments are being performed to increase permeability in low-permeability rock and improve our understanding of appropriate techniques and models required for developing enhanced geothermal systems. In order to design the second testbed, a ~50 m vertical HQ (96 mm) pilot borehole was drilled in June, 2019, to perform a series of mini-frac tests to determine rock stress state. Utilizing an elastic model based on the ISIP (Instantaneous Shut In Pressure), testing indicates that the minimum principal stress is 20.4 MPa oriented NNE (24°) and plunges at an angle of approximately 28°.
Revised: December 31, 2020 |
Published: August 3, 2020
Citation
Ingraham M., P.C. Schwering, J.A. Burghardt, C. Ulrich, T.W. Doe, B. Roggenthen, and R. Carson. 2020.Analysis of Hydraulic Fracturing on the 4100 Level at the Sanford Underground Research Facility. In 54th U.S. Rock Mechanics/Geomechanics Symposium, June 28-July 1, 2020, Virtual. Alexandria, Virginia:American Rock Mechanics Association.PNNL-SA-151703.