Geology of the Alberta Oil Sands Eric Timmer Earth and Atmospheric Sciences, University of Alberta Photo Courtesy of M. Gingras

Outline Oil sand deposits of Alberta Elements of the oil sands petroleum system: – Hydrocarbon source – Hydrocarbon migration – Reservoir – Trap/Seal – Microbial degradation Geological Challenges

Images Courtesy of M. Gingras

FigureCourtesy of M. Gingras

Elements of the Petroleum System From Adams et al. 2015

Hydrocarbon Source Rock From Adams et al. 2015

Migration From Adams et al. 2015

Image courtesy of M. Ranger

From Adams et al From Adams et al. 2004

Reservoir From Adams et al. 2015

Image Courtesy of M. Gingras

Versus Fluvial Channels Tidal Channels Schematics Courtesy of M. Gingras

Importance of Tidal Point Bars It is important to be able to predict the distribution of sedimentary facies to aid in the assessment of resource quality and quantity. A key marginal-marine facies is interbedded mud and sand deposited in tidally influenced point bars. The point-bar deposits are deleterious to resource value, as they are commonly mud-rich. However, they are predictable in their distribution and are, therefore, key indicators of paleogeographic position. Photo Courtesy of M. Gingras

Estuaries and deltas may contain meander-form through to straight channel geometries with complex local bar behaviour and sediment distribution. Bars coarsen rapidly laterally. Bars may coarsen upwards. Different scales of bars are imposed on each other by tidal maintainance. Photo Courtesy of M. Gingras

Tributaries may display very complex interactions with the main body of the estuary. Photo Courtesy of M. Gingras

Lettley, 2003

Salinity stressing leads to a very predictable distribution of trace fossils (ichnofossils), which are the tracks and trails of sediment- dwelling animals. Landward decrease in diversity. Landward shift to infaunal living into the brackish-water reach. Minimum abundance in association with greatest fluctuation in salinity. Images Courtesy of M. Gingras

Good Resource Poor Resource Best Resource Images Courtesy of M. Gingras

Trap/Seal From Adams et al. 2015

From Fustic et al. 2012

Microbial Degradation From Adams et al. 2015

Biodegradation Fundamentals Biodegradation occurs where anaerobic, methanogenic, microbes interact with hydrocarbons in zones where there are sufficient water-born nutrients and temperatures are < 80 C. Lighter-end saturated hydrocarbons are consumed preferentially—we are subsequently left with heavy oil/bitumen

Main Geological Challenges Reservoir Heterogeneity!!! Cap rock integrity/Overburden Thickness Groundwater Interaction

Reservoir Heterogeneity From Timmer et al. 2013

Cap rock/overburden thickness Clearwater Formation

Cap rock/overburden thickness Glacial Erosion

Ground Water Interactions From Timmer et al. 2013