Recognizing Duvernay B-Carbonate Distribution and its Potential Implications on Resource and Reserve Estimations

The Upper Devonian (Frasnian) Duvernay Formation of the Woodbend Group is a geological formation found over most of central Alberta. Since 2009, the Alberta Energy Regulator (AER) has seen a sharp increase in the number of operators targeting this liquids-rich shale resource, particularly in the Kaybob–Fox Creek area. Informal lithostratigraphic members include the A shale, the B carbonate (also referred to as the middle carbonate), and the C shale. The B carbonate is recognized to be non-reservoir. Recognizing the extent of the B carbonate is important. It needs to be removed from estimates of gross formation thickness that may otherwise be rich in organic carbon for credible in-place resource estimates. This can be problematic in that there are other carbonate-rich intervals of the A and C members that need to be included in gross thickness because they can contribute to reserves in these unconventional plays.