ABSTRACT

The Middle Devonian Norman Wells atoll reef complex contains 90 million cubic metres of original oil-in-place. Daily production of approximately 5,000 cubic metres makes it the largest contributor of conventional crude for Imperial Oil.

Detailed description of 33 cores recovered from the reservoir increased understanding of the facies and stratigraphic framework of the reef. Horizontal and vertical heterogeneities within the Kee Scarp reef demand an integration of geological detail and workover activities to maximize sweep efficiency. Reservoir heterogeneities are nowhere more prevalent than in the reef interior. The application of sequence stratigraphic concepts has resulted in the ability to differentiate and correlate significant surfaces within the thick monotonous succession of reef interior cycles. Groupings of four to seven stacked cycles, displaying an overall thinning-upward and shallowing-upward character, were correlated field-wide. The resultant reservoir framework constrains genetically-related facies distributions and spatially related reservoir units. Reservoir management is enhanced when this geological understanding is applied to workover strategies and reservoir pressure management, thus optimizing expected sweep of the reservoir.

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