Railbit, Dilbit and Synbit to Petcoke


In Canadian Alberta the tarsands are mined and, by other methods where the deposits are too deep, bitumen is extracted. Other than used on roads and roofs the bitumen has to be processed to a synthetic crude oil (SCO), also known as upgraded bitumen. It can then be refined into petrol, jet fuel or diesel.

Due to a lack of processing plant and the need for natural gas for the upgrading, only half of the bitumen produced is upgraded. Also there is insufficient refining capacity in Canada to take up the other half, even if it were to be upgraded. There is a demand for it in Texas, but to get it there is a problem as bitumen is too viscous to load into railcars without heating, or to be pipelined without dilution.

As railbit it can be accommodated in railcars with heating coils or moderately diluted. As dilbit with around 30% diluent (mainly pentanes) or, as synbit diluted with SCO, it can be pipelined South over the border to the US. The Keystone XL pipeline will augment the existing pipeline capacity of 400,000 barrels per day to 600,000 barrels per day.

A problem is that although some of the diluent can be separated from the dilbit at its destination, it is used as it is as a feedstock. This means that diluent must be procured in the US and pipelined North over the border to Alberta to make up further dilbit.

Petroleum coke

In a refinery the hydrocarbon number of the bitumen is lowered to upper and middle distillates by coking and hydrogenation. The coking process produces accumulating quantities of petroleum coke (petcoke), which is mainly carbon with vanadium and sulphur pollutants.  

In Alberta petcoke arises from the refineries in Edmonton and the US in refineries in Texas and elsewhere. It can be sold for burning in power plants, for augmenting coking coal and for carbon anodes for electrolysis, but it is unpopular and stockpiles are growing. There are around 100 million short tons of it in Alberta.

Because of its potential contribution to climate change, the best practice would be to put the petcoke back in the tarsands mines as landfill.

Rail transport

Because fracked well oil production falls off rapidly, there is great use made of road tanker transport of the tight oil and an increasing use of rail transport for bitumen deliveries instead of connecting transiently producing wells to pipelines. If the production is predominantly oil, the gas fraction is simply flared, as there is insufficient to justify a pipeline for its connection to a gas grid.

It means that Keystone XL has competition from rail, avoiding the disturbance of communities with the pipeline building.


Because there have been major spills of dilbit there has been major opposition to the building of Keystone XL.

It mainly favours Canada as it is able to export its un-upgraded bitumen and because of its foreign origin the refined products can be exported from the US avoiding the embargo on exporting indigenous crude oil and its products.  

It is likely that President Obama’s opposition to Keystone XL will be overturned by the Republicans in 2015, but it still may not go ahead with the rail competition, that from the tight oil production from the Eagle Ford shale play in Texas and that from the Bakken play across the Canadian/US border.  

John Busby 23 November 2014