Abstract

Middle Devonian carbonate rocks that host the Clarke Lake Gas Field south of the city of Fort Nelson have long been known to exhibit remarkable permeability and temperatures in excess of 110°C. This permeable dolomite aquifer is controlled by the diagenetic alteration of the original depositional trend of reef facies in the Keg River through Slave Point formations, and is over 200 m at its greatest thickness. A Monte-Carlo model estimate using the Volume Method of the recoverable thermal energy within the aquifer at Clarke Lake indicates the resource is significant in size (mean 10.1 × 10¹⁴ kJ; standard deviation 3.2 × 10¹⁴ kJ).

Using binary geothermal technology, this thermal energy can be used to generate electricity. It is estimated that purpose-built wells would be able to access enough thermal energy to generate more than 1 MW of electricity each. Geothermal plants could be supplied by multiple directional wells to provide greater capacity than is capable from a single well. The resource assessment indicates that the Clarke Lake field could be used to generate between 12 MW to 74 MW (mean 34 MW; standard deviation 10.8 MW) of electricity.