--> Abstract: Reservoir Characterization of the Middle Jurassic Upper Shaunavon Member in the Whitemud Pool, Southwest Saskatchewan, by Julianne D. Fic and Per Kent Pedersen; #90124 (2011)

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AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA

Reservoir Characterization of the Middle Jurassic Upper Shaunavon Member in the Whitemud Pool, Southwest Saskatchewan

Julianne D. Fic1; Per Kent Pedersen1

(1) Geoscience, University of Calgary, Calgary, AB, Canada.

The Upper Member of the middle Jurassic Shaunavon Formation is a mixed clastic/carbonate succession with regional cumulative production of 363 MMBbls from northeast-southwest trending shoreface sandstones. This study investigates the reservoir characterization and factors controlling production in the Upper Shaunavon B, one of four shoreface sequences within the Upper Shaunavon Member in the Whitemud Pool, southwest Saskatchewan. The Upper Shaunavon B shoreface sandstone is the thickest and most productive interval within the Whitemud Pool. Discovered in 1953, the Whitemud Pool’s cumulative production of 1.6 million barrels of an estimated 59 million Bbl OOIP yields an anomalously low recovery factor of 2.6% considering the oil is medium gravity crude (20-22 API gravity).

Operators initially targeted a high permeability coquina shell hash (10-1000mD) at the base of the Upper Shaunavon B shoreface sandstone as a means to drain the overlying, low permeability shoreface sandstones (1-10mD). A key question is if the overlying lower perm shoreface sandstones facies was adequately drained by the underlying coquina facies or is there a sizeable volume of oil reserves remaining? This study attempts to answer that question by focusing on the reservoir characterization of the two flow units, connectivity within and between the flow units and volumetrics of the flow units based on reservoir properties from both core and petrophysical logs. Integrating production data from wells that intersect both facies within the upper Shaunavon B as opposed to wells with the underlying high perm coquina facies absent will contribute to answering the anomalously low recovery factor within the pools.

Integration of geophysical well-logs, detailed core descriptions, thin sections and core analysis data provides insight to the facies interpretation, fairway widths, and lateral extent of depositional fairways for both units. Accurate reservoir characterization particularly within the tight ‘unconventional’ siliciclastic facies in the Whitemud pool coupled with horizontal drilling and completion technology will possibly create additional drilling opportunities within the Whitemud Pool. Significant as yet untapped reserves may elucidate why the recovery factor within the upper Shaunavon B is anomalously low.