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TitleInsights into contaminant transport from unconventional oil and gas developments from analog system analysis of methane-bearing thermal springs in the northern Canadian Rocky Mountains
AuthorFerguson, G; Grasby, S EORCID logo
SourceHydrogeology Journal vol. 26, issue 2, 2017 p. 481-493,
Alt SeriesNatural Resources Canada, Contribution Series 20170115
PublisherSpringer Nature
Mediapaper; on-line; digital
File formatpdf; html
ProvinceBritish Columbia; Alberta; Northwest Territories; Yukon
NTS84E; 84L; 84M; 85D; 94E; 94F; 94G; 94H; 94I; 94J; 94K; 94L; 94M; 94N; 94O; 94P; 95A; 95B; 95C; 95D
AreaRocky Mountains; Liard River; Horn River
Lat/Long WENS-128.0000 -118.0000 61.0000 57.0000
Subjectsfossil fuels; environmental geology; hydrogeology; structural geology; petroleum resources; hydrocarbons; gas; oil; petroleum industry; hydraulic fracturing; thermal springs; methane; pollutants; fluid migration; fluid flow; transport mechanisms; flow velocities; bedrock geology; lithology; sedimentary rocks; shales; carbonates; structural features; faults; folds; permeability; geothermal temperatures; thermal analyses; heat flow; temperature; anomalies; groundwater; groundwater flow; groundwater regimes; aquifers; hydraulic head; hydraulic gradients; recharge rates; modelling; tectonic setting; deformation; sedimentary basins; Montney Basin; Liard Basin; Horn River Basin; Toad River Spring; Rocky Mountain Deformation Front; Phanerozoic; Mesozoic; Triassic; Paleozoic; Permian; Carboniferous; Devonian; Silurian; Precambrian
Illustrationslocation maps; cross-sections; schematic cross-sections; graphs; tables; geoscientific sketch maps; stratigraphic charts
ProgramEnergy Geoscience
Released2017 09 05
AbstractNatural gas is currently being produced from shales of the Montney and Liard basins in western Canada. Production requires hydraulic fracturing due to the low permeability of the shales in the basins. Stratigraphically equivalent shales are present in the northern Canadian Rocky Mountains. Thermal springs with notable hydrocarbon concentrations occur where large-scale faults intersect the same shale units that are the focus of gas development, indicating that under certain circumstances, connection of deep fractured shales to the land surface is possible. To constrain these conditions, simulations were conducted for the spring with the highest hydrocarbon flux (Toad River Spring), results of which indicate that in order to supply sufficient water to a fault to support measurable advection, the effective permeability of the shales in these structurally deformed areas must be one to four orders of magnitude higher than in areas of active gas production to the east. The spatial scale of enhanced permeability is much greater than that which is achieved by hydraulic fracturing and the mechanism of maintaining high pressures at depth is more persistent in time. Examination of groundwater velocities suggests that upward migration of solutes from hydraulic fracturing may take decades to centuries. Results also indicate that any temperature anomaly will be associated with transport along a fault at such velocities. No such temperature anomaly has been documented in regions with unconventional oil and gas development to date. Such an anomaly would be diagnostic of a deep solute source.
Summary(Plain Language Summary, not published)
Shale gas development is active in the Liard Basin and there is an underlying concern that fracturing can lead to communication of deep gas bearing units with the surface environment. The same shale units occur in the mountain belts to the west where thermal springs discharge waters with high methane concentrations. This study showed a deep cutting fault allowed rapid movement of fluids to surface as well as regional fracturing of shales that occurred as a result of mountain building. The natural conditions are far beyond the fracture systems induced by industry in areas of development, suggesting that it would be difficult to reproduce these natural conditions that allow deep communication by shale gas development. However, results also show that within the mountain belts deep communication pathways already exist, and greater concern is warranted should industry extend exploration into that region. Currently there is no shale gas exploration in the mountain belts.

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