Abstract

The study area of this paper encompasses Townships 28 to 34 of Ranges 23 to 29 west of the Third Meridian. In addition to large quantities of light oil and gas from the Viking Formation, the Kindersley area contributed about 28 per cent of the 97,663,000 barrels (15.53 × 10⁶m³) of heavy oil produced in Saskatchewan to the end of 1972.

Jurassic sediments are absent in this area, and the Cretaceous Mannville Group is directly underlain by deeply eroded and altered Palaeozoic strata. The hills and valleys of the pre-Cretaceous erosion surface have mostly gentle slopes. Mississippian beds subcrop in the southern part of the area, and there is an apparent Mississippian outlier in the northern part.

Stratigraphic proximity to this erosion surface is a characteristic of the known commercial heavy-oil accumulations. They occur in three different rock units: the Mississippian Middle Bakken Sandstone Member, the Residual Zone and a basal sand body of the Cretaceous Mannville Group. Small quantities of heavy oil have also been found in the Devonian Birdbear Formation and in other sands of the Mannville Group.

The largest and most prolific pools occur in the Middle Bakken reservoirs, which are mainly light grey, fine-grained, quartzose, calcareous sandstones. The Residual Zone, which lies beneath the unconformity, has been derived by weathering and decomposition of Mississippian Madison beds. The dominant rock type is an argillaceous chert breccia. Most of the oil from the Residual Zone has come from one well. All the commercial Manville oil production has been from a single reservoir near the base of the group consisting of unconsolidated, fine quartz sand.

The API gravity of most of the Kindersley heavy oil varies between 13° and 15° (979 to 966 Kg m³). Waterfloods have been installed in the Coleville Bakken Sand, North Hoosier Bakken Sand and North Hoosier Basal Blairmore Sand Pools with very favourable responses. A pilot hot water injection project has been installed in the Buffalo Coulee Bakken Sand Pool, and one well has been converted to salt water disposal in the Alsask Basal Blairmore Sand Pool.