When a skimmer removes oil locally, oil floating further away will flow
toward it. The maximum flow rate toward the skimmer defines its natural
capacity. Traditional skimmer-capacity modeling considers flow driven by height
potential and resisted by inertial forces but neglects viscosity. On the basis
of theory and experiments, this paper claims that high oil viscosity may govern
the skimmer capacity.
It is shown that viscous resistance relates to a dimensionless quantity
called the Goose number, representing the ratio of inertial to viscous forces.
At high Goose numbers, viscosity may be neglected. At sufficiently low Goose
numbers, viscous resistance dominates. A numerical solution applicable to all
Goose numbers has been developed. Analytical formulas for skimmer capacity at
high and low Goose numbers are provided.
A scaled laboratory facility was built to investigate the skimming of
viscous oil. The measured rates were consistent with the numerical predictions
and with the formula for low Goose number. With decreasing viscosity,
predictions by the current model converged to traditional formulas that neglect
The model quantifies how skimming capacity is affected by size and by
properties of the oil spill and skimmer geometry and submergence. This may
enable more rational skimmer design and operation, and even optimization.
© 2010. Society of Petroleum Engineers
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- Original manuscript received:
10 April 2009
- Meeting paper published:
24 March 2009
- Revised manuscript received:
19 March 2010
- Manuscript approved:
2 April 2010
- Published online:
19 August 2010
- Version of record:
15 March 2011