Geothermal resource assessment of remote sedimentary basins with sparse data: lessons learned from Anticosti Island, Canada (original) (raw)
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Geomechanics and Geophysics for Geo-Energy and Geo-Resources
Geothermal resource quantification requires underground temperature and volume information, which can be challenging to accurately assess at the regional scale. The analytical solution for steady-state heat conduction with internal heat generation is often used to calculate temperature at depth, while geological models can provide volume information. Both approaches were originally combined in a single 3D geological model, in which the underground temperature is directly computed, to accurately evaluate geothermal resources suitable for power generation in the St. Lawrence Lowlands sedimentary basin covering 18,000 km 2 in Quebec, Canada, and improve methods for geothermal resource quantification. This approach, used for the first time at such a large scale, allowed to determine the volume of each thermal unit providing a detail assessment of resource depth, temperature and host geological formation. Only 5% of geothermal resources at a temperature above 120°C that is suitable for power generation were shown to be hosted in the Cambro-Ordovician sedimentary rock sequences at a depth of 4 to 6 km, while 95% of the resource is hosted by the underlying Precambrian basement.
Deep Geothermal Heating Potential for the Communities of the Western Canadian Sedimentary Basin
Energies
We summarize the feasibility of using geothermal energy from the Western Canada Sedimentary Basin (WCSB) to support communities with populations >3000 people, including those in northeastern British Columbia, southwestern part of Northwest Territories (NWT), southern Saskatchewan, and southeastern Manitoba, along with previously studied communities in Alberta. The geothermal energy potential of the WCSB is largely determined by the basin’s geometry; the sediments start at 0 m thickness adjacent to the Canadian shield in the east and thicken to >6 km to the west, and over 3 km in the Williston sub-basin to the south. Direct heat use is most promising in the western and southern parts of the WCSB where sediment thickness exceeds 2–3 km. Geothermal potential is also dependent on the local geothermal gradient. Aquifers suitable for heating systems occur in western-northwestern Alberta, northeastern British Columbia, and southwestern Saskatchewan. Electrical power production is lim...
The south-eastern territory of the province of Québec (Eastern Canada), a region located along the Saint-Lawrence River Valley, including the Gaspésie Peninsula and the Madeleine and Anticosti Islands, has been identified as an interesting area for the future use of deep geothermal energy several decades from now. This region includes a thick 1-5 km sedimentary rock wedge deepening southwest towards the Appalachian disturbed belt front. The deep part of the sedimentary wedge offers the potential to produce geothermal heating and power from the deep aquifers in the future. Relatively elevated heat flow densities in some thermal anomalous areas (i.e. >60 mW/m 2 ) also result in prospects for temperatures above 120°C at about 4 km in the sedimentary aquifers. Additionally, geothermal power and heat production from hot dry deep granites located below the sedimentary cover can also be considered using Enhanced Geothermal Systems (EGS). On the other hand, Northern Québec, a vast territory covering nearly 1.2 million km 2 of land located north of the 49 th parallel, presents very low mean annual surface temperatures and a relatively low average heat flow density of about 40 mW/m 2 . This area would require deeper drilling for heat mining, i.e. 80°C at a depth of about 4.5 km. In the medium and long terms, geothermal energy could be feasible in the province of Québec with positive future energy and environmental impacts.
Geothermal potential of the St. Lawrence Lowlands sedimentary basin from well log analysis
Geothermics, 2018
The heterogeneous distribution of minerals in different rock types poses several challenges for assessing thermal conductivity, heat flow and temperature of sedimentary basins, especially when databases coming from the oil sector are the only source of information. The objective of this study was to develop a new methodology that uses well log data to better infer the thermal conductivity variations of sedimentary formations in order to evaluate heat flow and extrapolate temperature at depth. The methodology was applied to the St. Lawrence Lowlands basin, with constrains from the available oil and gas database not designed for geothermal exploration purposes. The main idea was to analyze quantitatively well log data with an inversion approach from limited reference wells and derive empirical relationships to calculate a thermal conductivity profile for each available well. Pressure and temperature corrections were then considered. These continuous logs of thermal conductivity were used to estimate the Earth's heat flux density using bottomhole temperatures and to extrapolate temperature at depth. A modified version of Poisson's equation was solved by the finite difference method for this purpose. The average temperature and its standard deviation obtained with this approach for the St.
2014
Heat flow and geothermal gradient of the sedimentary succession of the Western Canada Sedimentary Basin (WCSB) are mapped based on a large thermal database. Heat flow in the deep part of the basin varies from 30 mW/m 2 in the south to high 100 mW/m 2 in the north. As permeable strata are required for a successful geothermal application, the most important aquifers are discussed and evaluated. Regional temperature distribution within different aquifers is mapped for the first time, enabling a delineation of the most promising areas based on thermal field and aquifer properties. Results of previous regional studies on the geothermal potential of the WCSB are newly evaluated and discussed. In parts of the WCSB temperatures as high as 100-210 °C exist at depths of 3-5 km. Fluids from deep aquifers in these "hot" regions of the WCSB could be used in geothermal power plants to produce electricity. The geothermal resources of the shallower parts of the WCSB (>2 km) could be used for warm water provision (>50 °C) or district heating (>70 °C) in urban areas.
Energies, 2014
Heat flow and geothermal gradient of the sedimentary succession of the Western Canada Sedimentary Basin (WCSB) are mapped based on a large thermal database. Heat flow in the deep part of the basin varies from 30 mW/m 2 in the south to high 100 mW/m 2 in the north. As permeable strata are required for a successful geothermal application, the most important aquifers are discussed and evaluated. Regional temperature distribution within different aquifers is mapped for the first time, enabling a delineation of the most promising areas based on thermal field and aquifer properties. Results of previous regional studies on the geothermal potential of the WCSB are newly evaluated and discussed. In parts of the WCSB temperatures as high as 100-210 °C exist at depths of 3-5 km. Fluids from deep aquifers in these "hot" regions of the WCSB could be used in geothermal power plants to produce electricity. The geothermal resources of the shallower parts of the WCSB (>2 km) could be used for warm water provision (>50 °C) or district heating (>70 °C) in urban areas.
Environmental Earth Sciences, 2015
Northern Québec, a large and cold climate territory located north of the 49th parallel, has low average heat flow density (40 ± 9 mW/m 2) typical of the Canadian Shield. The lack of the thermal blanket otherwise provided by sediments in the platform of southern Québec results in deep drilling requirements for potential mining heat (80°C at some 5 km). Drilling doublet or triplet well systems at such depths into low-enthalpy granitic rocks would be expensive; however, in some cases of heat flow higher by one standard deviation of the mean and fracked permeability allowing flow rates [30 kg/s may make this heat useable in the future. Other options in providing heat are more likely to be applied earlier. These would include shallow geothermal energy use with heat pumps in granites by placement of artificial heat exchanges by directional loop drilling. These systems may have promise in Northern Québec due to its very cold climate and extremely high energy cost based on diesel oil heating for remote communities and mining areas. Findings show that recent industrial age climatic warming increased the mean underground temperatures in the upper circa couple hundred meters. This has resulted in temperature gains and energy ground storage.
Journal of Geophysics and Engineering, 2010
While previously examined only for Alberta , the potential for the Enhanced Geothermal System (EGS) concept, as outlined by the MIT report , is examined here for all of Canada. Enhanced (or Engineered) Geothermal Systems are engineered reservoirs that have been created to extract economical amounts of heat from low permeability and/or porosity geothermal resources. Temperatures greater than 150 °C at depths less than 7km are required. To evaluate target areas for potential EGS heat mining across Canada we have constructed detailed heat flow and depth-temperature maps to determine the geothermal resource base in conduction dominated systems (sedimentary basins and crystalline basment). We also determined the quantity of thermal energy (heat content available from deep hot rocks). We evaluate thermal energy availability for 3 depth slices (3-4 km; 6-7 km and 9.5-10.5 km) in a 4 km by 4 km grid.
Resources, 2015
Heat flow of the sedimentary succession of the Eastern Canada Sedimentary Basins varies from 40 mW/m 2 close to the exposed shield in the north to high 60-70 mW/m 2 in the southwest-northeast St. Lawrence corridor. As high fluid flow rates are required for a successful geothermal application, the most important targets are deep existing permeable aquifers rather than hard rock, which would need to be fracked. Unfortunately, the ten most populated Québec urban centers are in the areas where the Grenville (Canadian Shield) is exposed or at shallow depths with sedimentary cover where temperatures are 30 °C or less. The city of Drummondville will be the exception, as the basement deepens sharply southwest, and higher temperatures reaching >120 °C are expected in the deep Cambrian sedimentary aquifers near a 4-5-km depth. Deep under the area where such sediments could be occurring under Appalachian nappes, temperatures significantly higher than 140 °C are predicted. In parts of the deep basin, temperatures as high as 80 °C-120 °C exist at depths of 3-4 km, mainly southeast of the major geological boundary: the Logan line. There is a large amount of heat resource at such depths to be considered in this area for district heating.
Energies
Shallow, low-temperature geothermal resources can significantly reduce the environmental impact of heating and cooling. Based on a replicable standard workflow for three-dimensional (3D) geothermal modeling, an approach to the assessment of geothermal energy potential is proposed and applied to the young sedimentary basin of Pisa (north Tuscany, Italy), starting from the development of a geothermal geodatabase, with collated geological, stratigraphic, hydrogeological, geophysical and thermal data. The contents of the spatial database are integrated and processed using software for geological and geothermal modeling. The models are calibrated using borehole data. Model outputs are visualized as three-dimensional reconstructions of the subsoil units, their volumes and depths, the hydrogeological framework, and the distribution of subsoil temperatures and geothermal properties. The resulting deep knowledge of subsoil geology would facilitate the deployment of geothermal heat pump technology, site selection for well doublets (for open-loop systems), or vertical heat exchangers (for closed-loop systems). The reconstructed geological-hydrogeological models and the geothermal numerical simulations performed help to define the limits of sustainable utilization of an area's geothermal potential.