Paper No. 4-9
Presentation Time: 10:20 AM
THE KISMET (PERMEABILITY (K) AND INDUCED SEISMICITY MANAGEMENT FOR ENERGY TECHNOLOGIES) PROJECT – AN UNDERGROUND FIELD LABORATORY FOR INVESTIGATING THE RELATIONS BETWEEN NATURAL AND INDUCED FRACTURES, STRESS FIELD, AND ROCK FABRIC
kISMET is part of the US Department of Energy’s Subsurface Technology & Engineering Research (SubTER) crosscutting initiative for adaptive control of fractures, reactions, and flow in the subsurface. The project is located at the Sanford Underground Research Facility (SURF) in the former Homestake gold mine in Lead, SD. The kISMET site consists of five closely spaced near-vertical boreholes on the 4850 level that are designed for a series of hydraulic fracturing stress measurements and induced-fracture stimulation experiments. Four of the boreholes are HQ-sized holes that are 50 m in depth and will host monitoring sensors; in conjunction with a central NQ borehole they form a five-spot pattern at depth. The monitoring boreholes are located ~3 m away from the central borehole, allowing for very precise monitoring of fracture initiation and growth. The host rock is the Poorman Formation, a highly foliated phyllite that is steeply dipping at the kISMET site. Initial characterization of the site is being conducted using core samples, televiewer logs, and extensive preexisting geologic data. A straddle packer assembly will be installed at several depths in the central borehole to conduct stress measurements, and later to perform a series of hydrofracture stimulations. Preliminary analytical and numerical fracture initiation and growth model simulations conducted using existing geomechanical data for the Poorman phyllite suggest rock breakdown pressures in the range of 35-50 MPa. Two primary methods will be employed to monitor the experiments: continuous active-source seismic monitoring (CASSM) and electrical resistivity tomography (ERT); these will be complemented by passive microseismic (MEQ), pore pressure and injection rate monitoring. These experiments are aimed at understanding the effects of stress state, rock fabric, existing fractures, and stimulation approach on the character of the fracture(s) created (e.g., permeability enhancement, size, orientation, aperture), the fracturing process, and the associated induced microseismicity. Results of this research will be directly applicable to fracture stimulation and reservoir creation in Enhanced Geothermal Systems (EGS).