Overview of the kISMET Project on Intermediate-Scale Hydraulic Fracturing in a Deep Mine

In support of the U.S. DOE SubTER Crosscut initiative, a team comprising national laboratory and university researchers has established a field test facility in a deep mine. Initial activities were aimed at in situ hydraulic fracturing experiments to characterize the stress field, understanding the effects of crystalline rock fabric on fracturing, and gaining experience in stimulation monitoring using geophysical methods. The kISMET (permeability (k) and Induced Seismicity Management for Energy Technologies) project test site was established in the West Access Drift of the Sanford Underground Research Facility (SURF) nominally 4850 ft (1478 m) below ground in phyllite of the Precambrian Poorman Formation. The kISMET team drilled and cored five near-vertical boreholes in a line on 3 m (10 ft) spacing, deviating the two outermost boreholes slightly to create a five-spot pattern around the test borehole centered in the test volume 40 m below the drift invert (floor). We present an overview of activities and results in the areas of site selection, laboratory studies, pre-test modeling, and hydraulic fracturing and monitoring.