H070-08
The EGS Collab Project: Stimulation and Flow at the 10-meter scale

Wednesday, 9 December 2020: 10:58
Virtual
Timothy J Kneafsey1, Doug Blankenship2, Patrick F Dobson3, Joseph Morris4, Mark D White5, Pengcheng Fu4, Hunter Anne Knox2, Lianjie Huang6, Paul Schwering2, Jonathan Blair Ajo-Franklin7, Earl Mattson8, Ghanashyam H Neupane8, Jon Weers9, Christopher E Strickland5 and EGS Collab Team, (1)Lawrence Berkeley National Laboratory, Berkeley, CA, United States, (2)Sandia National Laboratories, Albuquerque, NM, United States, (3)Lawrence Berkeley Nat Lab, Berkeley, CA, United States, (4)Lawrence Livermore National Laboratory, Livermore, CA, United States, (5)Pacific Northwest National Laboratory, Richland, WA, United States, (6)Los Alamos National Laboratory, Geophysics Group, Los Alamos, NM, United States, (7)Rice University, Earth, Environmental and Planetary Sciences Department, Houston, TX, United States, (8)Idaho National Laboratory, Idaho Falls, ID, United States, (9)National Renewable Energy Laboratory Golden, Strategic Energy Analysis Center, Golden, CO, United States
Recorded Presentation
Abstract:
The EGS (enhanced geothermal systems) Collab project is stimulating rock and inducing flow in fractures adjacent to a deep mine tunnel. Our goals are to create flow through reservoirs in fractured rock on the ~10 m scale and compare and validate reservoir model predictions with field experimental data. We are working to elucidate the fundamental relationship among stress, seismicity, and permeability enhancement, and identify and quantify the nature of stimulation and other key governing parameters that impact fracture permeability. In validating reservoir model predictions, we will improve tools for the Frontier Observatory for Research in Geothermal Energy (FORGE) and EGS implementation. We have completed one experiment at 1.5 km depth in the Sanford Underground Research Facility in Lead, SD, USA. In this experiment we drilled 8 boreholes, one for injection, one for production, and 6 for monitoring, and instrumented the wells. We characterized our host rock using laboratory testing and numerous field-based geophysical and geological techniques, and created a well-instrumented test bed to allow us to reliably monitor fracture stimulation events and flow tests. We created a 10 m scale reservoir in the rock by performing a number of stimulations, and were able to flow chilled water to the production well for almost a year capturing > 90% of the injected water. We performed a number of tracer tests with the goal of correlating effective heat transfer behavior from inferred system properties (e.g.: effective surface area, fluid residence times). Our simulations successfully described the seemingly disparate rapid tracer arrivals and slow thermal depletion, observed from these tests. We quantified numerous behaviors, some of which we attributed to poroelasticity perhaps combined with mineral precipitation or biofouling, thermoelastic responses, and recorded dynamic flow pathways not resulting from applied stimuli. We simulated many of our tests (geomechanics, hydrology, geochemistry, tracer) resulting in a much-improved understanding of our system. Many high-quality data sets have been collected, are in analysis, and are available for further study.

This project is supported by the U.S. DOE Geothermal Technologies Office (GTO) under Contract No DEAC02-05CH11231 with Lawrence Berkeley National Laboratory.

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