integrative geothermal resource assessment study for the siliciclastic Granite Wash Unit, northwestern Alberta (Canada)

This study explores the siliciclastic Granite Wash Unit in northwestern Alberta as a potential geothermal reservoir. The approach covers regional 3D structural geological modelling of a 90 km × 70 km area based on well log and legacy 2D seismic data. The fault strike was interpreted from lineaments, which were identified with the refined trend surface analysis method. The stress state of the Granite Wash reservoirs was determined by an integrated approach of 3D fault modelling, stress ratio definition based on frictional constraints, and slip tendency analysis. The results show that the best site for a geothermal application is located in the southwestern study area, where the highest temperatures (above 70 °C) coincide with the largest thickness (above 20 m) and zones of elevated porosity and permeability. The integrated stress analysis indicates an in situ stress regime from normal to strike-slip faulting maintaining a non-critically stressed reservoir or faults therein, assuming a friction coefficient of 0.7. The granite wash reservoirs could be used for heating of greenhouses, domestic warm water provision and district heating.