[1] The subsurface temperature field beneath Winnipeg, Canada, is significantly different from that of the surrounding rural areas. Downward heat flow to depths as great as 130 m has been noted in some areas beneath the city and groundwater temperatures in a regional aquifer have risen by as much as 5°C in some areas. Numerical simulation of heat transport supports the conjecture that these temperature changes can be largely attributed to heat loss from buildings and the temperature at any given point is sensitive to the distance from and the age of any buildings. The effect is most noticable when buildings are closely spaced, which is typical of urban areas. Temperature measurements in areas more than a few hundred meters away from any heated structure were only a few tenths of a degree Celsius greater than those observed outside the city, suggesting that other reasons for increases in subsurface temperature, such as changes in surface cover or climate change, may be responsible for some of the some of the observed increase in temperatures. These sources of additional heat to the subsurface make it difficult to resolve information on past climates from temperatures measured in boreholes and monitoring wells. In some areas, the temperature increases may also have an impact on geothermal energy resources. This impact might be in the form of an increase in heat pump efficiency or in the case of the Winnipeg area, a decrease in the efficiency of direct use of groundwater for cooling.

The Paradox Basin in the Colorado Plateau (USA) has some of the most iconic records of paleofluid flow, including sandstone bleaching and ore mineralization, and hydrocarbon, CO2, and He reservoirs, yet the sources of fluids responsible for these extensive fluid-rock reactions are highly debated. This study, for the first time, characterizes fluids within the basin to constrain the sources and emergent behavior of paleofluid flow resulting in the iconic rock records. Major ion and isotopic (δ18Owater; δDwater; δ18OSO4; δ34SSO4; δ34SH2S; 87Sr/86Sr) signatures of formation waters were used to evaluate the distribution and sources of fluids and water-rock interactions by comparison with the rock record. There are two sources of salinity in basinal fluids: (1) diagenetically altered highly evaporated paleo-seawater-derived brines associated with the Pennsylvanian Paradox Formation evaporites; and (2) dissolution of evaporites by topographically driven meteoric circulation. Fresh to brackish groundwater in the shallow Cretaceous Burro Canyon Formation contains low Cu and high SO4 concentrations and shows oxidation of sulfides by meteoric water, while U concentrations are higher than within other formation waters. Deeper brines in the Pennsylvanian Honaker Trail Formation were derived from evaporated paleo-seawater mixed with meteoric water that oxidized sulfides and dissolved gypsum and have high 87Sr/86Sr indicating interaction with radiogenic siliciclastic minerals. Upward migration of reduced (hydrocarbon- and H2S-bearing) saline fluids from the Pennsylvanian Paradox Formation along faults likely bleached sandstones in shallower sediments and provided a reduced trap for later Cu and U deposition. The distribution of existing fluids in the Paradox Basin provides important constraints to understand the rock record over geological time.

Abstract. Modelling of surface temperature change effect on temperature vs. depth and temperature-depth logs in Western Canada Sedimentary Basin show that SAT (surface air temperature) forcing is the main driving factor for the underground temperature changes diffusing with depth. It supports the validity of the basic hypothesis of borehole temperature paleoclimatology, namely that the ground surface temperature is systematically coupled with the air temperature in the longer term (decades, centuries). While the highest groundwater recharge rate used in the modelling suggests that for this extreme case some of the observed curvature in the profile, could be due to groundwater flow, it is more likely that the low recharge rates in this semi-arid region would have minimal impact. We conclude that surface temperature forcing is responsible for most of the observed anomalous temperature profile.

Canada has enormous geothermal energy resources that could supply a renewable and clean source of power. There are many constraints, however, in utilizing this energy resource, including geological, technical, and regulatory issues. The intent of this report is to examine the geothermal potential in Canada, and the geological controls on the distribution of high grade resources as well as controls on the economic development and production of geothermal energy. This assessment is based on a new compilation and digitization of data produced through over 48 years of geothermal research in Canada. Recommendations on current and future research needs to reduce barriers to resource production are made at the end of the report. Currently Canada has no geothermal electrical production; however, direct use and heat exchange systems are used widely. Several projects are currently being examined by industry and government to develop electrical potential in Canada. A key economic constraint for these projects is the high risk of exploration due to costs of deep drilling. The cost of delivered geothermal power is projected to decline and be competitive with coal fired production within the next 15 years, given current levels of technology. Canada's in-place geothermal power exceeds one million times Canada's current electrical consumption (Fig. 1). However, only a fraction of this total potential could be developed. Much of the resource lies beyond current drilling technology, outside of areas served by high-capacity transmission lines, and at some distance from load centres. Nonetheless, the available high grade geothermal resource is considerable. High temperature hydrothermal systems can be brought on line with proven technology. Many of the tools required to bring geothermal energy to full realization, however, are not commercially proven to date and require further research and technology development. We can expect a strong learning curve and price response as geothermal energy is developed while other energy sources such as coal and nuclear will begin to see fleet and capacity retirements.

No abstract

No abstract

No abstract

No abstract