Identification of a thermal maturation high, revised maturity map, and production trends of the Late Devonian Duvernay Formation, Alberta, Canada.

The Late Devonian Duvernay Formation in the Western Canada Sedimentary Basin is a prolific shale reservoir that has been developed since 2010 and produced 250 million barrels of oil equivalent. Regional thermal maturity trends across central and southern Alberta published in the literature are poorly understood and inconsistent with produced fluid types. The focus of this dissertation is to refine thermal maturity trends of the Duvernay Formation. The Duvernay is subdivided into three hydrocarbon production areas that are, from west to east, Kaybob, Willesden-Green, and Innisfail. The maturity proxies used in this study are from solid-state 13C Nuclear Magnetic Resonance (NMR) and Rock Eval’s Tmax along with publicly available Tmax data, produced fluid types, and the structural burial depth trends across the basin. Thermal maturity across these areas increases to the southwest except for Willesden-Green. The southern portion of the Innisfail region reaches oil maturity whereas Kaybob ranges from oil to gas mature. Willesden-Green is markedly more mature than Kaybob as indicated by NMR (P=0.05) and Tmax (P=0.00) proxies even though samples from both areas were collected at similar depths (P=0.24). This thermally anomalous trend is named the Willesden-Green Maturity High (WGMH). The origin of the WGMH is interpreted to be related to an increase in geothermal gradient induced by the convective flow of hydrothermal fluids through a fault and fracture network stemming from the reactivation of the Snowbird Tectonic Zone during the Laramide Orogeny. Successful Duverney hydrocarbon production is related to both thermal catagenesis and optimal reservoir mineralogic composition as estimated from whole core elemental geochemistry. Elemental geochemistry was measured from continuous whole core at a 1-m sample interval using handheld X-ray fluorescence (XRF). Major elements are used as a proxy for mineralogy and redox-sensitive trace element enrichment as an indicator of depositional anoxia. Silica and calcium are used to estimate the relative abundance of quartz and calcite, respectively. High quartz and/or calcite mineral proportions increase rock brittleness and susceptibility to induced fracture stimulation. The eastern portion of the Kaybob region has the most productive oil and gas wells and correspondingly high concentrations of silica and redox-sensitive trace metals.