Lithological, diagenetic, and organic controls on reservoir quality in the lower triasic Montney Formation, Pouce Coupe, Alberta

Abstract

The Lower Triassic Montney Formation is a major gas producer in the Western Canadian Sedimentary Basin. The tight gas/shale resources associated with this formation, however, are notoriously difficult to characterize using conventional methodologies due to the presence of heterogeneities below the scale of traditional log and core analysis. An innovative methodology is applied to investigate lithologic, diagenetic, inorganic and organic matter controls on permeability within the formation. Using a core gathered from the Pouce Coupe field, vertical permeability variations along the core were quantified using profile permeability. Microfacies were defined and compared with the profile permeability measurements; this comparison revealed that the finely laminated and uncemented regions were more permeable than areas of thicker bedding. Additional diagenetic and mineralogic controls on permeability were revealed through analysis of XRD and electron microprobe data. Organic matter was characterized using petrography and a slow heating Rock-Eval pyrolysis procedure, which demonstrated that the hydrocarbon in the samples primarily consists of a network of migrated, refractory bitumen. Profile permeability shows no strong relationship to the distribution of refractory hydrocarbons, suggesting that the organic matter does not contribute to permeability and may in fact be a flow inhibitor.