| Title | Insights into contaminant transport from unconventional oil and gas developments from analog system analysis of methane-bearing thermal springs in the northern Canadian Rocky Mountains |
| Author | Ferguson, G; Grasby, S E |
| Source | Hydrogeology Journal vol. 26, issue 2, 2017 p. 481-493, https://doi.org/10.1007/s10040-017-1662-5 |
| Year | 2017 |
| Alt Series | Natural Resources Canada, Contribution Series 20170115 |
| Publisher | Springer Nature |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf; html |
| Province | British Columbia; Alberta; Northwest Territories; Yukon |
| NTS | 84E; 84L; 84M; 85D; 94E; 94F; 94G; 94H; 94I; 94J; 94K; 94L; 94M; 94N; 94O; 94P; 95A; 95B; 95C; 95D |
| Area | Rocky Mountains; Liard River; Horn River |
| Lat/Long WENS | -128.0000 -118.0000 61.0000 57.0000 |
| Subjects | fossil 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; unconventional energy resources; Phanerozoic; Mesozoic; Triassic; Paleozoic; Permian; Carboniferous; Devonian; Silurian; Precambrian |
| Illustrations | location maps; cross-sections; schematic cross-sections; graphs; tables; geoscientific sketch maps; stratigraphic charts |
| Program | Geothermal Assessments, Energy Geoscience |
| Released | 2017 09 05 |
| Abstract | Natural 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. |
| GEOSCAN ID | 302785 |
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