Dilbit (diluted bitumen) is a means of transporting highly viscous hydrocarbon. Per the Alberta Oil Sands Bitumen Valuation Methodology, "Dilbit Blends" means "Blends made from heavy crudes and/or bitumens and a diluent usually condensate, for the purpose of meeting pipeline viscosity and density specifications, where the density of the diluent included in the blend is less than 800 kg/m3."[1] If the diluent density is greater than or equal to 800 kg/m3, the diluent is typically synthetic crude and accordingly the blend is called synbit.[2]
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Why dilute bitumen? [link]
Bitumen and heavy oils are often produced from remote deposits such as the Athabasca oil sands in Alberta, Canada and the Orinoco tar sands in Venezuela. Before 1980, most produced bitumen was transported by truck, but trucking is seasonally restricted and relatively inefficient and expensive compared to pipeline transport. However, bitumen in its undiluted state is too viscous and dense to be transported by pipeline. To create a fluid capable of transportation by pipeline, bitumen must be mixed with a fluid that has much lower viscosity and will keep bitumen from precipitating out of the mixture. By 1985 and demonstrating the effectiveness of dilbit, Alberta Energy Company was operating dual pipelines to transport diluent from Edmonton to Cold Lake and dilbit from Cold Lake to Edmonton.[3] Dilbit is now also transported by rail.[4]
How is bitumen diluted? [link]
The most common diluent used to dilute bitumen is natural gas condensate (NGC), especially the naptha component. Due to insufficient quantity of natural gas condensate, bitumen shippers also use refined naptha and synthetic crude oil (SCO) as diluent. Although SCO requires a higher volume percentage to achieve the same viscosity, at least one study found that SCO provides better blend stability than NGC.[5] Shippers dilute bitumen before shipment in order to meet viscosity and density requirements found in common carrier pipeline tariff rules. A National Energy Board study assumed a standard dilbit containing 33% condensate (resulting in product with "21.5 °API and sulphur content of 3.3 percent") and synbit containing 50% SCO.[6] By selecting different diluent types and blend ratios, bitumen shippers attempt to lower component costs, increase blend value, and maintain pipeline transportability. The blend ratio may consist of 25 to 55% diluent by volume, depending on characteristics of the bitumen and diluent, pipeline specifications, operating conditions, and refinery requirements.[3]
What happens to the dilbit? [link]
Diluent can be removed from dilbit by distillation and reused. Alternatively, the entire dilbit can be refined. Dilbit and synbit are typically processed by refineries as heavy or medium crudes, respectively.[6] As dilbit contains hydrocarbons at extreme ends of the viscosity range, the material can be more difficult to process than typical crude oil. Therefore, dilbit normally constitutes only a small portion of a refinery's total feedstock.
Alternatives to diluent [link]
- Heated pipelines
- Constructing upgraders closer to production
See also [link]
- Canadian Centre for Energy Information
- Drill bit
- History of the petroleum industry in Canada (oil sands and heavy oil)
- Syncrude
- Suncor
- CNRL
References [link]
- ^ (pdf) Alberta Oil Sands Bitumen Valuation Methodology, 2008-9995, Calgary, Alberta: Canadian Association of Petroleum Producers, Dec 2008, https://www.capp.ca/getdoc.aspx?DocId=144465&DT=NTV
- ^ Canada's Oil Sands: Opportunities and Challenges to 2015 (Energy Market Assessment). Calgary, Alberta: National Energy Board. May 2004. pp. 115-118. ISBN 0-662-36880-0. https://www.neb.gc.ca/clf-nsi/rnrgynfmtn/nrgyrprt/lsnd/pprtntsndchllngs20152004/pprtntsndchllngs20152004-eng.pdf. Retrieved 14 Mar 2012. Condensate: "A mixture comprised mainly of pentanes and heavier hydrocarbons recovered as a liquid from field separators, scrubbers or other gathering facilities or at the inlet of a natural gas processing plant before the gas is processed." Dilbit: "Bitumen that has been reduced in viscosity through addition of a diluent (or solvent) such as condensate or naphtha." Diluent: "Any lighter hydrocarbon, usually pentanes plus, added to heavy crude oil or bitumen in order to facilitate its transport on crude oil pipelines." Synbit: "A blend of bitumen and synthetic crude oil that has similar properties to medium sour crude." "Synthetic crude oil is a mixture of hydrocarbons generally similar to light sweet crude oil, derived by upgrading crude bitumen or heavy crude oil."
- ^ a b Walker, Ian C. (1998) (pdf), Marketing Challenges for Canadian Bitumen, Tulsa, OK: International Centre for Heavy Hydrocarbons, p. 2, https://www.oildrop.org/Info/Centre/Lib/7thConf/19980101.pdf
- ^ Harrison, Lynda (September 2011). "Riding the Rails, Oil companies climb aboard potential alternative to pipelines". Oil & Gas Inquirer (Calgary, Alberta: JuneWarren-Nickle's Energy Group). https://www.oilandgasinquirer.com/printer.asp?article=magazine%2F110912%2FMAG2011_SC0000.html. Retrieved 14 Mar 2012.
- ^ Rahimi, Parviz; Alem, Teclemariam (10 Feb 2010). "Crude Oil Compatibility and Diluent Evaluation for Pipelining" (pdf). Joint CCQTA/COQA meeting (New Orleans). Devon, Alberta: National Centre for Upgrading Technology. https://geoscan.ess.nrcan.gc.ca/text/geoscan/fulltext/NCUT2009_Paper28.pdf. Retrieved 18 Jun 2011.
- ^ a b Canada's Oil Sands: Opportunities and Challenges to 2015 (Energy Market Assessment). Calgary, Alberta: National Energy Board. May 2004. ISBN 0-662-36880-0. https://www.neb.gc.ca/clf-nsi/rnrgynfmtn/nrgyrprt/lsnd/pprtntsndchllngs20152004/pprtntsndchllngs20152004-eng.pdf. Retrieved 14 Mar 2012.
