Upper Mannville Mclaren Channel Sandstones: Depositional Characteristics and Innovative Reservoir Management Techniques

Garnet D. Turcotte¹, Bill Thornton², and Jim Walters^3
1 P. Geol., Independent Consultant, Calgary, AB
² P.Eng., Western Canada Oil Sands, Calgary, AB
³ P. Geophys., Pengrowth Corporation, Calgary, AB

The Mclaren channel trend extends over 50 miles from SE to NW forming a narrow trend of excellent heavy oil reservoirs containing over 1.0 billion barrels of OOIP. This distributary system passes over a pre-Cretaceous subcrop that contains significant reserves of Mississippian Bakken oil that is thought to have a common oil source. Mclaren point-bar sandstones are re-incised and aggraded into reservoirs with up to 30m of pay and permeability of over 5 Darcies. Seismic definition of these pools is excellent due to high contrast of overlying shale with reservoir sandstones. Gas caps add an increased contrast where present.

Recently drilled wells have provided insights into the variability within these pools that is more significant than originally thought. This is discussed from a regional perspective and an internal viewpoint is given based on 3D seismic evaluation. An understanding of internal reservoir aspects will play a role in the design of the ultimate development and recovery of this resource.

Primary recovery techniques have yielded less than 5% of this oil due to the highly viscous nature of the oil and the presence of bottom water. Additional infill drilling for primary oil requires diligence due to issues including marginal economics, potential loss circulation and well interference. EOR projects have yielded higher recoveries, but have been largely uneconomic due to present high fuel costs. The recovery of additional oil from these partly pressure-depleted pools will require innovation and experimentation.

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