Geothermal exploration of Paleozoic formations in Central Alberta

Abstract

This study explores the distribution of Paleozoic formations in the Central Alberta Basin and investigates rock properties with regard to their usability as geothermal reservoirs. The study area of this regional-scale investigation is about 160 km × 200 km in size and located around Edmonton where the basin depth ranges between 1.8 and 3.5 km. A three-dimensional (3D) geological model was developed based on stratigraphic tops from about 7000 wells from the database of the Alberta Geological Survey (AGS). Spatial distribution and thickness of deep formations were established in the 3D geological model. Porosity and permeability of four Devonian carbonate formations — Cooking Lake, Leduc, and Nisku formations, and Wabamun Group — were investigated using data from more than 50 000 core analyses. Average porosity of the Devonian strata in the study area ranges from 4.5% (Nisku) to 8.7% (Wabamun), average permeability is between 3.5 × 10−15 m2 (Wabamun) and 26 × 10−15 m2 (Leduc). The distribution of both parameters was analyzed using geostatistical methods. Based on an average geothermal gradient and the geometry of formations from the 3D modeling study, an estimation of formation temperatures for the Paleozoic formations is presented. Temperature in the Cambrian Basal Sandstone Unit ranges from 62 °C in the shallower northeast (1.8 km) to 122 °C in the deeper southwest (3.5 km); temperature in the Devonian strata ranges from 22 to 87 °C. With these new results, potential geothermal reservoirs can be delineated in the Alberta Basin around Edmonton, enabling future detailed exploration and field development.

Implications of Spatial Variability in Heat Flow for Geothermal Resource Evaluation in Large Foreland Basins: The Case of the Western Canada Sedimentary Basin

“…In 2013 the British Columbia Ministry of Energy and Mines assessed the geothermal resource in the Devonian Carbonates of the Clarke Lake gas field in northeastern British Columbia [16]. In central Alberta Weides et al [17] mapped porosity, permeability and temperature of four Devonian carbonate aquifers and the Cambrian Basal Sandstone Unit [18], concluding that all five formations are potentially useable for geothermal heating applications. Using a similar approach, Weides et al [19] investigated the geothermal potential of the siliciclastic Granite Wash Unit in northwestern Alberta.…”

“…Figure 2 shows examples of core samples from some of the formations. Figure 4 for location of the study areas; data is taken from [13] for Calgary, [16] for Clarke Lake, [17,18] for Edmonton, [12] for Hinton-Edson, [19] for Peace River, and [14,20] for Saskatchewan. Temp.…”

“…Though the extension of geological formations can be mapped over large distances with manageable effort, the facies of the formations, which controls the distribution of porosity and permeability, must always be investigated on a smaller scale. It is possible to map facies or reservoir properties such as porosity on a large scale, using well logs and core analysis data for example (see [17,19]). However, to obtain a reliable facies map for the scale of the WCSB, an enormous amount of well data would need to be collected, interpreted, classified and mapped, which is beyond the scope of this paper.…”

Geothermal Exploration – Ensuring an Optimized Utilization of Geothermal Energy in Low-enthalpy Sedimentary Settings

“…Methods applied include 3D geological modelling merging a dataset from more than 7000 boreholes, the reinvestigation of hydraulic core data, and the realization of new core measurements where data is scarce (Weides et al, 2012). In the North German Basin, the evaluation of rock thermal properties to describe the thermal field was in the focus over several year of research.…”

From oil field to geothermal reservoir: First assessment for geothermal utilization of two regionally extensive Devonian carbonate aquifers in Alberta, Canada

“…While such conditions suggest a reasonable to good potential for geothermal utilization, previous studies provided very few hard data on the geothermal and/or petrophysical reservoir properties of the rocks (e.g. Majorowicz and Weides, 2014;Weides et al, 2013;Nieuwenhius et al, 2015;Ardakani and Schmitt, 2016). However, an extensive data base on 5 parameters such as porosity, permeability, thermal conductivity, and others, is necessary for a geothermal assessment, especially with complete parameter sets for every single sample (Clauser, 2006;Sass and Götz, 2012;Homuth et al, 2015).…”