Basal water-bearing zone of the oil-sands deposits of the Cretaceous McMurray Formation at Christina Lake, Alberta, Canada

The Cretaceous McMurray Formation at Christina Lake in Alberta, Canada contains bitumen-rich sand bodies in the lower part. These sand bodies were deposited in lowstand fluvial systems with the onset of relative sea-level rise in the Western Canada foreland basin, forming thick interconnected bodies along the paleovalley. Oil recovery from these reservoirs commonly suffers from bottom water, which reduces not only pay thickness but also the efficiency of thermal recovery processes. For successful oil production in this area, basal water-bearing zone should be investigated and incorporated in determining optimistic well locations and operational strategies. Examination of 455 wireline logs reveals a widespread water-bearing zone at the basal part of the McMurray Formation at Christina Lake. The basal water-bearing zone is relatively thick on paleotopographic lows, particularly along the paleovalley. This result suggests that paleotopography played a crucial role in the distribution of the basal water-bearing zone.