Multiphase hydromechanical iTOUGH2-EOS7C modeling study of underpressure development in shale during glacial loading cycles at the Bruce Nuclear Site, Ontario, Canada

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Abstract

A deep geologic repository (DGR) for low- and intermediate-level radioactive waste has been proposed at the Bruce nuclear site on the eastern flank of the Michigan Basin in southeastern Ontario, Canada. The repository would be placed at a depth of ~680 m, within a ~450 m-thick sequence of geologic media with extremely low porosity and permeability. The water in this section is significantly underpressured, which previous modeling work has shown could be the result of hydromechanical coupling during geologically recent glacial cycles. However, questions have been raised about whether gas phase methane is present in situ, and if so, how it relates to the generation and persistence of the underpressure here, as well as those in numerous other shale- and gas-rich sedimentary basins around the world. The primary goal of this study is to investigate, using the hydromechanical multiphase flow simulator iTOUGH2-EOS7C, what impact separate phase methane may have on coupled hydromechanical processes during glacial cycles. This was done by observing pressure evolution in a one-dimensional iTOUGH2-EOS7C model designed as a simplified representation of the Bruce site and its geologically recent history. Results indicate that, although gas phase generally dampens pressure changes in response to glacial loading, a similar underpressure to the one observed at the Bruce site could feasibly occur in a multiphase system.

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Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title Multiphase hydromechanical iTOUGH2-EOS7C modeling study of underpressure development in shale during glacial loading cycles at the Bruce Nuclear Site, Ontario, Canada
Year Published 2018
Language English
Publisher Lawrence Berkeley National Laboratory
Contributing office(s) National Research Program - Eastern Branch
Description 5 p.
Larger Work Type Book
Larger Work Subtype Conference publication
Larger Work Title Proceedings of the TOUGH Symposium 2018
First page 314
Last page 318
Conference Title TOUGH Symposium 2018
Conference Location Berkeley, CA
Conference Date October 8-10, 2018
Country Canada
State Ontario
County Bruce County
Other Geospatial Bruce Nuclear Site