Properties of Canadian Bitumen and Bitumen-Derived Crudes, and Their Impacts on Refinery Processing

The production of bitumen and heavy oil from the Western Canadian Sedimentary Basin, including the Cold Lake, Athabasca, and Peace River regions, has increased in the last 10 years and currently reaches to approximately 2.7 million bbl/d. Although a large portion of the produced bitumen is processed in Alberta, a significant amount is transported by pipeline and rail to different refineries in Canada and the United States. Due to their high viscosity and density, bitumen and heavy oils must be blended with diluents (dilbit) or synthetic oil (synbit) to meet pipeline specifications for density (940 kg/m3) and viscosity (350 cSt at 11 °C). Other processing options such as partial upgrading are being considered to reduce or eliminate the diluent requirement for bitumen transportation to the market. Canadian heavy crudes are also categorized as "opportunity crudes" partly because of a relatively high total acid number (TAN) content, although there are no public data available on the refinery corrosivity of these crudes. Although the large discount of Canadian heavy crudes such as Western Canadian Select compared to West Texas Intermediate may be due to lack of pipeline capacity, part of the price reduction is imposed because of the quality and perceived refinery processing issues that may occur as a result of processing Canadian heavy crudes. In this chapter, I review the properties of Canadian heavy oils and bitumen revealing how these oils, in fact, have superior quality compared to light and tight oils and create less operational problems in refinery processes. Data will be presented showing that the conversion chemistry leading to lighter products is facilitated because of the presence of hydrogen donors as well as hydrogen transfer molecules in Canadian bitumen. Canadian bitumen has one of the highest stabilities among the heavy oils in the world. In refinery processing, Canadian dilbits have shown to have the lowest fouling tendencies and as such can be blended with light or tight oils to reduce fouling from these crudes in refinery operations. Finally, I will demonstrate that at a high temperature (300 °C), heavy gas oil (HVGO) derived from Canadian bitumen, despite relatively high TAN, has lower activity toward Fe powder compared to HVGO derived from a known corrosive crude with a lower TAN. © 2019 American Chemical Society.