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Thursday, February 23, 2017


Posted to Maritime Musings (by on December 21, 2012

A form of heavy oil found primarily in Canada and Venezuela

Bitumen or asphalt is a naturally-occurring form of petroleum or crude oil.  Unlike common crude oil, though, it is highly viscous and often semi-solid.  In previous times, it was referred to as pitch.  Ancient peoples used bitumen for a variety of purposes, including on torches, for waterproofing, and to bind bricks together in construction.  Nowadays, it is used primarily in road construction and in roofing.  Increasingly, though, it is being refined into petroleum products.  Because obtaining and refining bitumen is more expensive than obtaining and refining traditional crude oil, it is only done when large quantities are available.  The two largest known deposits of bitumen are in the Athabasca oil sands of northern Alberta, Canada and in the Orinoco oil sands of northeastern Venezuela.  Unfortunately, refineries to convert the bitumen into petroleum products are not co-located with either deposit.  As a result, the crude bitumen must be transported by ship or pipeline to the refineries.  Crude bitumen, even after extraction from the oil sands, is not amenable to such transport.  The process for converting bitumen into a transportable form involves mixing the crushed bitumen with about 30% water and a small amount of surfactant.  The Orinoco oil sands were exploited first and experimented with using phenol as the surfactant, raising health concerns.  Currently, alcohol-based surfactants are used.  The resulting material is transportable and, similar to heavy fuel oil, can be burned in power plants.  It tends, though, to have a specific gravity greater than water, meaning that if spilled, a significant fraction of the spilled material will submerge into the water column.  This can complicate spill response efforts.  The US Coast Guard has promulgated regulations requiring special spill response equipment and techniques when preparing plans for transporting so-called “Group V” oil through waters of the United States.


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