Geothermics of the Phanerozoic Strata of Saskatchewan

Knowledge of geothermal conditions is required for petroleum exploration, basin modeling, hydrogeological, geothermal energy exploitation and CO₂ sequestration studies. The Saskatchewan Phanerozoic Fluids and Petroleum Systems (SPFPS) project is investigating the movement of subsurface fluids in Saskatchewan and one of its objectives is to explore the subsurface thermal conditions of the Phanerozoic strata in the province.

Province-wide temperature data were compiled from different sources: bottom hole temperatures from log headers; temperature profiles from industrial and scientific temperature logs; temperatures recorded while conducting drill stem tests and other pressure and production surveys. Thermal conductivity data for different rock types that were required for heat flow calculations were obtained from literature sources. New methods for culling non-representative temperature data were developed and applied in this study. Thermally altered measurements (e.g., measurements influenced by surface temperatures, steam injection, hydrocarbon production, etc.) were removed to ensure that only representative values were used for constructing maps. Depth and elevation specific temperature maps, as well as temperature maps for key Phanerozoic formations in Saskatchewan were created from the processed data.

Temperature values range from 5°C to over 100°C in the strata between the surface and the Precambrian basement. Temperatures increase with depth, the highest values being observed in the early Palaeozoic formations in the deepest part of the Canadian portion of the Williston Basin, near Estevan. Elevation and depth specific maps show anomalous temperature highs in the shallower layers near Swift Current, Regina, Moose Jaw, and Estevan. Geothermal gradients between the surface and the Precambrian basement vary between 10°C/km and 40°C/km. Previously known thermal anomalies near the edge of the Phanerozoic strata have been studied and cannot be replicated. Thus this study has established a new, more detailed, more accurate picture of the temperature field of the Phanerozoic strata of Saskatchewan.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California