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TitleSpill behaviours of pipeline-transportable processed bitumen products in fresh water
AuthorXin, Q; Hounjet, L J; Hartwell, A
SourceFuel vol. 309, 122040, 2022 p. 1-9,
Alt SeriesNatural Resources Canada, Contribution Series 20220025
Mediapaper; digital; on-line
File formatpdf
Subjectsfossil fuels; bitumen; petroleum; oil spills; environmental impacts
Illustrationsflow diagrams; tables; distribution diagrams; plots
ProgramCanmetENERGY - Devon Director, Upstream and Environmental Impacts - Upstream and Environmental Impacts Operations
Released2021 10 02
AbstractBitumen extracted from Canada's oil sands resources is an abundant, unconventional crude oil used to produce liquid fuels. To permit its transportation by transmission pipelines from production sites to upgraders and refineries, the highly-viscous bitumen must first be blended with up to 50 vol% of light oil ("diluent") to produce a diluted bitumen (DB) with sufficiently low viscosity and density. Diluents occupy substantial pipeline capacity, and are relatively expensive, so Canada is developing "partial upgrading" processes to reduce the diluent content of pipeline-transportable bitumen products. Such processes lower bitumen's density and viscosity by removing some portion of its heaviest, asphaltene-rich fraction by, for instance, solvent-induced separation and/or thermochemical conversion. Thus, processed bitumen products (PBPs) require less diluent to meet specifications for transmission pipeline transportation. We compare the minimum diluent content requirements of several PBPs meeting such specifications for density (? 940 kg/m3 at 15.0 ?C) and viscosity (? 350 cSt at a pipeline temperature of 10.6 ?C, selected on the basis of DB viscosity measurements). In this work, PBPs meeting pipeline transportation specifications are prepared by visbreaking and/or solvent-deasphalting of bitumen followed by dilution with 32-47 wt% less diluent than the corresponding unprocessed DB. Public concern about environmental risks associated with spillage of emerging PBPs during transportation has spurred investigations of these products' interactions with water. With little currently known about their aquatic behaviours, we evaluate the emulsification and dispersion tendencies of pipeline-transportable PBPs after mixing these with fresh water following a reported protocol, and compare these results with those for DB, bitumen-derived synthetic crude (SC) oil, and conventional crude (CC) oil. The characteristics of floating water-in-oil emulsions are shown to depend upon the oil's asphaltene content and thermochemical process history. At high mixing energy, dispersed oil content within the water column is seen to increase with oil resin-to-asphaltene ratio. In the aquatic system employed, oil content of the water column is greatest for SC, followed by solvent-deasphalted products and DB, followed by only-vis-broken product and CC. These results may aid in the development of oil spill behaviour models and response plans needed for transporting PBPs.
Summary(Plain Language Summary, not published)
When crude oils spill from pipelines, they can negatively affect sensitive aquatic environments. Although much is now known about the aquatic behaviours of unprocessed, heavy crude oils called "diluted bitumen products," less is understood about the behaviours of processed bitumen products, which are now being transported by pipelines. This lack of understanding has raised concerns about how the spills of processed bitumen products may affect aquatic environments. Processing bitumen removes some of its heaviest components so that less of the lighter diluent needs to be added to make the oil flow through a pipeline. In order to better understand their aquatic behaviours, we have prepared a series of processed bitumen products that met pipeline transportation specifications. We have mixed each product with water to see how much oil is left in the water column and how much water is retained by the floating oil-rich emulsion. We have then compared the aquatic behaviours of these processed products with those of unprocessed diluted bitumen, as well as conventional crude oil and synthetic crude oil. We have found that processing bitumen in different ways makes the products behave differently when mixed with water.

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