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Coupled Processes in Geoengineering: Nuclear waste, Geothermal and Carbon Sequestration

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Lawrence Berkeley National Laboratory, Berkeley, California

Abstract: Coupled thermal-hydro-mechanical (THM) processes modeling is indispensable for the design and performance assessment of subsurface engineering activities. Coupled THM numerical models are most useful if they can be validated against field observations at relevant spatial and temporal scales for the problem at hand. In this presentation, three examples of such large-scale coupled processes model validations are presented. The model simulations were conducted with the TOUGH-FLAC simulator that was first developed and applied twenty years ago associated with previous plans for a nuclear waste repository at Yucca Mountain, Nevada, U.S.A. At Yucca Mountain, coupled processes model validation was conducted against several underground experiments, culminating with the Yucca Mountain Drift Scale test, which still to date is the largest underground heating experiment in the world. The second example involves the Northwest Geysers Enhanced Geothermal Systems (EGS) Demonstration Project. This EGS demonstration project is located at the margin of The Geysers geothermal field, California; the largest geothermal energy producer in the world. The Northwest Geysers EGS Demonstration Project involved hydraulic simulation of a cubic kilometer sized rock volume during a one-year massive cold-water injection into the very hot >250C steam-filled fracture rock. The final example involves coupled THM processes modeling at the In Salah CO2 storage project in Algeria. At In Salah, a coupled THM model was validated against field observations of ground surface deformation monitoring by satellite (InSAR) technology. Detailed modeling of the observed ground surface uplift also revealed the creation of a large-scale fracture zone, about 5 km long, in the lower part of the caprock, which eventually lead to the termination of the project. These three examples, along with numerous other studies, demonstrate the great value of effective coupled THM modeling for design and performance of subsurface energy resources exploration and storage.

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Bio: Dr. Jonny Rutqvist is a Senior Scientist and Head of Hydrogeology Department, Energy Geosciences Division, at the Lawrence Berkeley National Laboratory (LBNL). He holds a PhD degree in Engineering Geology from the Royal Institute of Technology, Sweden. For over 30 years, Dr. Rutqvist’s research has been focused on geomechanics and modeling of coupled thermal, hydraulic, mechanical, and chemical (THMC) processes in geological media for a wide range of geoscientific and geoengineering applications, including geologic carbon sequestration, nuclear waste disposal, geothermal energy extraction, unconventional oil and gas, and underground energy storage. Dr. Rutqvist has authored over 200 peer-reviewed journal papers, and is a four-time recipient of the American Rock Mechanics Association (ARMA) Awards.