LABORATORY-BASED SIMULATIONS OF SPILLS OF DILUTED BITUMEN VS. CONVENTIONAL CRUDE

Over the last 20 years, crude oil production in Canada has doubled, with much of this increase coming from Alberta’s oil sands. Oil sands crude is extracted as bitumen, which has a much higher viscosity than conventional crude. The bitumen is diluted with lighter hydrocarbons (diluent) to form diluted bitumen which has a viscosity similar to conventional crudes to allow for pipeline transport. Given that some organic compounds present in conventional crude and diluted bitumen will dissolve into water, one concern relates to the potential environmental impacts of a spill of diluted bitumen on surface water and groundwater resources.

In this study, we are simulating pipeline spills using groundwater tank experiments to compare the potential impacts of diluted bitumen and conventional crude oil. Experiments have been conducted using sand-filled tanks where groundwater flow is simulated by injecting water and oil through a port at the upstream end of the tank, and then sampling the water downstream from this injection point.

Initial experiments, focused on simulating a spill of both types of crude oil occurring below the water table, resulted in higher concentrations of toluene, ethylbenzene and xylene for water impacted by conventional crude, while benzene concentrations were similar. The concentrations of organic species dissolved in water naturally correlates with concentrations of these compounds in the crude oil. In addition to organics, some metals dissolved in the aqueous phase are also sourced from the Diluted Bitumen, including Co, Cr, Fe and V. Elevated concentrations of these metals do not to occur in the aqueous phase with Conventional Crude.

For spills occurring above the water table, the concentrations of dissolved organics from conventional crude were greater than those from a diluted bitumen spill. However, dissolved concentrations associated with diluted bitumen are much lower than the simulated conventional crude spill test. This presentation will include results to date.