Geological Risk Assessment of Development Opportunities within the Devonian Leduc Formation at Sturgeon Lake South Field, Alberta, Western Canada Sedimentary Basin

Jon Koenig¹, Julia Kahmann¹, Stacy Atchley¹, Jeff R. Sluggett², and Lawrence West^2
1 Baylor University, Waco, TX
² Chariot Energy, Inc, Calgary, AB

The stratigraphic entrapment of oil and gas within Devonian carbonate buildups accounts for approximately half of the total hydrocarbon reserves in the Western Canada Basin. The Sturgeon Lake South field (SLS) ranks sixth out of 161 producing fields from the Devonian Woodbend Group Leduc Formation in regards to original-oil-in-place (OOIP). As of August, 2004, cumulative hydrocarbon production from SLS was approximately 195 million barrels of oil equivalent. This value suggests that 98% of estimated recoverable-oil-in-place and 57% of OOIP have been produced. Comparable Woodbend fields have recovery factors ranging between 62 to 86%.

To refine the understanding of OOIP and recoverable reserves relative to hydrocarbons produced to date, and to better understand the stratal geometries and regional controls on accommodation history, a detailed sequence stratigraphic model was constructed for SLS. This model, which incorporates approximately 1258 meters of core from 70 wells, wireline logs from 243 wells, and a composite 3D seismic survey across the eastern two-thirds of SLS, indicates an initial episode of progradation followed by a terminal phase of pronounced stratal retrogradation.

Application of the sequence stratigraphic model indicates an upward revision of the OOIP from 290 to 453 million barrels of oil equivalent. Furthermore, cumulative production to date suggests only 37% recovery, a number that is 25-49% lower than similar Woodbend fields. From this, we conclude that down-space drilling (i.e. from 80 to 40-acre) is warranted.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005