An 80-page report published by Environment Canada, the Department of Fisheries and Oceans and Natural Resources Canada reviewed the fate of crude oil in saltwater.
It assessed two grades of diluted bitumen and found they both floated on saltwater when water was free of sediment.
"When fine sediments were suspended in the saltwater, high-energy wave action mixed the sediments with the diluted bitumen, causing the mixture to sink or be dispersed as floating tarballs," the report said.
A 2010 spill of Canada's heavier grade of crude oil in Michigan was difficult for energy company Enbridge to clean up because the oil sank and mixed in with sediment at the bottom of a river.
Transport of Canadian crude oil through the planned Northern Gateway and Keystone XL, and others, has raised the hackles of environmental groups concerned about spills. The Canadian report, published Tuesday, said the study was conducted as part of strategy to implement a world-class spill response.
The report said testing was done in a laboratory setting and acknowledged outcomes may be different in an actual spill of oil products. It added that finding a chemical dispersant that would work on the heavier grade of crude oil would be challenging.