It is critical that companies upgrading heavy oil understand the impact of Synthetic Crude Oil (SCO) properties on the ability to market feedstocks to conventional refineries in the USA. Due to the proximity and existing pipeline infrastructure, the USA is a natural market for crude oils derived from Alberta's oil sands deposits. There are also significant political drivers for the USA to develop crude supplies in a country with which it has strong cultural, economic, and political ties.
This paper outlines the key properties of refined distillates and discusses how these properties are affected by the various hydrocarbon components contained in bitumen derived crude oil. The impact of integrating bitumen and SCO into a conventional refinery are also discussed in terms of its ability to meet these important distillate specifications.
Synthetic crude oil has unique properties compared to conventional crude oils that required special considerations. These qualities make upgrading bitumen to saleable products more difficult than upgrading a conventional sweet crude which has been the historical feedstock to US refineries.
A conventional refiner in the US faces a number of issues when considering running bitumen derived feedstocks, either synthetic crude oil (SCO) or bitumen blends. Some of the processing issues include a lack of heavy conversion capacity, insufficient metallurgy to process high acid crude oils, and difficulties meeting final product specifications.
This paper will focus on the difficulties in meeting key product properties while producing diesel, jet fuel, and FCC feed from SCO and bitumen.
Bitumen Characteristics In its natural state, bitumen is an extra-heavy oil with the consistency of roofing tar. It contains significant quantities of asphaltene material and is highly aromatic. Due to its heavy nature, bitumen has high levels of sulfur, nitrogen, and metals. Bitumen also contains organic acid compounds at levels high enough to cause serious corrosion issues in downstream processing units.
On its own, bitumen cannot be sent directly to US refiners since it does not meet pipeline density and viscosity specifications. For bitumen to enter into US markets, it must be blended with a lighter material to form dilbit or synbit, or it must be upgraded to SCO. The diluent used for bitumen can be either a light hydrocarbon (gas condensate or naphtha) to form dilbit or a full range sweet synthetic crude oil to form synbit. Dilbit is approximately 20–30% condensate, while synbit is approximately 50% bitumen, 50% synthetic crude. The target pipeline specifications are gravity >19 °API and viscosity <350 cSt at the designated temperature (usually ground temperature).
Diesel Fuel Diesel fuels are considered to be the hydrocarbon compounds boiling between 500 – 650 °F. While outside of the USA and Canada, diesel is a significant light duty passenger vehicle transportation fuel, in the USA and Canada diesel is primarily used in heavy-duty transportation and industrial equipment.
In the USA, on-road diesel (the largest diesel market1) properties must as a minimum meet the specifications in ASTM D-9752. Canadian automotive diesel quality is governed by CGSB 3–517, which is similar to the ASTM D-975 specification.
