SW Sask: Lower Shaunavon

The Middle Jurassic Shaunavon Formation is divided into a lower and an upper member based on lithological differences. Isopach maps of both units show that the maximum gross isopach of the formation is about 50m. Both members contain oil, which is hydrodynamically trapped. The lower member is a porous (generally 14%–18%), but tight (generally below 1 mD), open marine authigenic shelf limestone capped by fossiliferous oolitic shoals. The oolites, which were deposited under high energy conditions and are partly dolomitized, constitute the reservoir. Production from the lower member has become economic with the application of horizontal technologies. Vertical wells were mostly uneconomic due to the relatively thin and tight reservoirs.