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TitleSalt dissolution and permeability in the Western Canada Sedimentary Basin
AuthorWoroniuk, B; Tipton, K; Grasby, S EORCID logo; McIntosh, J C; Ferguson, G
SourceHydrogeology Journal vol. 27, issue 1, 2018 p. 161-170,
Alt SeriesNatural Resources Canada, Contribution Series 20180181
PublisherSpringer Nature
Mediapaper; on-line; digital
File formatpdf; html
ProvinceSaskatchewan; Manitoba; Alberta
NTS62; 63A; 63B; 63C; 63D; 63E; 63F; 63G; 63H; 63I; 63J; 63K; 63L; 72; 73A; 73B; 73C; 73D; 73E; 73F; 73G; 73H; 73I; 73J; 73K; 73L
AreaMontana; North Dakota; Canada; United States of America
Lat/Long WENS-111.0000 -97.0000 55.0000 48.0000
Subjectshydrogeology; geochemistry; geophysics; groundwater; groundwater flow; modelling; sedimentary basins; bedrock geology; lithology; sedimentary rocks; evaporites; salt deposits; halite; anhydrite; carbonates; breccias; hydraulic analyses; permeability; drill stem tests; fractures; precipitation; groundwater geochemistry; geophysical logging; Western Canada Sedimentary Basin; Williston Basin; Prairie Evaporite Formation; Dawson Bay Formation; Souris River Formation
Illustrationslocation maps; stratigraphic columns; geophysical logs; geoscientific sketch maps; plots; frequency distribution diagrams
ProgramGroundwater Geoscience Program Management - Groundwater Geoscience
Released2018 09 20
AbstractExtensive dissolution of evaporites has occurred in the Williston Basin, Canada, but it is unclear what effect this has had on bulk permeability. The bulk of this dissolution has occurred from the Prairie Evaporite Formation, which is predominantly halite and potash. However, minor evaporite beds and porosity infilling have also been removed from the overlying Dawson Bay and Souris River formations, which are predominantly carbonates. This study examines whether permeability values in the Dawson Bay and Souris River formations have been affected by dissolution, by analyzing 142 drillstem tests from those formations. For both the Dawson Bay and Souris River formations, the highest permeabilities were found in areas where halite dissolution had occurred. However, the mean permeabilities were not statistically different in areas of halite dissolution compared to those containing connate water. Subsequent precipitation of anhydrite is known to have clogged pore spaces and fractures in some instances. Geochemical relationships found here support this idea but there is no statistically significant relationship between anhydrite saturation and permeability. Geomechanical effects, notably closure of fractures due to collapse, could be a mitigating factor. The results indicate that coupling dissolution and precipitation to changes in permeability in regional flow models remains a significant challenge.
Summary(Plain Language Summary, not published)
To understand the long term stability of fluids in sedimentary basins in Canada it is essential to be able to develop models of how fluids move through the rock. One critical question is do areas where buried salt has been removed through natural processes have any significant change to rock properties that would affect how we model basin scale fluid flow. Results of this work show that there is not any significant statistical difference in rock properties where salt removal has occurred, suggesting that models do not need to be modified to take this into account.

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