The Countess field produces oil and gas from zones in eight geological formations from the Upper Cretaceous Belly River to the Mississippian Pekisko. The principal producing zones are the Lower Cretaceous Glauconitic and Ostracod (Mannville) Sandstones, at an average depth of 1,097 m (3,600 ft). These zones were deposited as offshore sandstone bars on submarine topographic highs, caused by underlying Pekisko cuestas. The bars are encased in marine Mannville shales. The sandstones are gray to brown, fair to well-sorted and subrounded to rounded. Porosities average 22%; permeabilities average 580 md. Reservoir thickness averages 9.75 m (32 ft). The productive sandstones cover approximately 4,243 hectares (10,500 acres). The reservoir contained approximately 34,136,000 cu m f oil (215,000,000 bbl) of which approximately 12,288,000 cu m (77,300,000 bbl) or 36% will be recoverable. In addition, the reservoir contained 3,826,000,000 cu m of gas of which 60% or 2,295,000,000 cu m (81,500,000,000 cu ft) will be recoverable. Other formations will produce 32,980,000,000 cu m of gas. Twelve dry holes, drilled prior to November 1965, a drilling density of 1.7 wells per township, indicated the probable presence of this stratigraphic trap. A wildcat drilling program of 34 wells was designed to explore the seven townships. Three of the first four exploratory wells were dry. One was a discovery. Finally, seventeen of the exploratory wells were successful and seventeen were dry. The statistical exploration method, an adequate number of wildcat tests, for this large geogr phical area resulted in the ultimate exploratory success.

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