Oil sands bitumen is partially upgraded to facilitate the pipeline transportation with environmental and economic benefits. In this work, the corrosion performance of a candidate constructional material for partial upgrading, UNS S31603, was evaluated under the environments of cyclic thermal cracking of bitumen at 360 and 400 °C. Sample coupons were exposed to gas phase and liquid phase to simulate the constructional materials for distillation tower and partial upgrader, respectively. At both temperatures, the samples are not susceptible to gas phase corrosion but liquid phase corrosion. Advanced microscopy techniques and the grazing incidence X-ray diffraction were used to examine the corrosion products. Sulfidation appears to be the major corrosion mechanism under the thermal cracking of oilsands bitumen.
With the rapid economic development and the dramatic population growth, the demand on clean energy is continuously increasing.1 Due to the depletion of conventional crude oil reserves, the unconventional oil resources such as oil sands become more attractive.2 Canada has a total estimated oil sands reserves of 161.4 billion barrels by the end of 2020, accounting for 9.3% of the global reserves.3 The bitumen in the oil sands is extracted and transported through pipelines to the refineries with refining capabilities in Canada and the United States where the raw bitumen is processed to produce marketable synthetic crude oil (SCO). The proposed TransCanada system planned to connect the Alberta bituminous oil sands to the refineries as far as in Texas.4
Bitumen is highly viscous and hardly flows at ambient conditions, so the transportation of bitumen in pipelines is usually associated with the addition of diluent to achieve the viscous reduction purpose. The purchase of diluent, the separation of diluent at destination refineries, and the subsequent transportation of diluent back to the oil sand field greatly increase the operation costs. On the other hand, as the upgrading product of bitumen, SCO, has reducing competitivity with the light crude in the US market. As a result, Canadian oil sands producers tend to partially upgrade the oil sands bitumen to target heavy crude refineries.5 Meanwhile, the partially upgraded bitumen has much lower viscosity compared to the raw bitumen and is easy to flow in the pipeline with less or zero amount of diluent.
