Bitumen reserves in oil sands in Alberta, Canada, represent one of the biggest such deposits in the world. The Athabasca region contains the bulk of this resource and the lower Cretaceous McMurray Formation contains the most significant target interval. Inclined heterolithic strata and associated sand accumulations comprise most of the formation. However, the distribution of bitumen in the formation varies due to the high degree of facies heterogeneity throughout the deposit. This lithological heterogeneity causes difficulties in interpreting geology and estimating the bitumen distribution.