Rise Velocity of Live-Oil Droplets in Deep-Sea Oil Spills

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degassing, droplet rise velocity, gas saturation, high pressure, live oil

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Numerous models have been developed for calculating the fate of crude oil and natural gas plumes after deep-sea oil spills. One of the most important input parameters for these models is the rise velocity of fluid particles under the extreme environmental conditions in the deep sea (high pressure, low temperature). Consideration of these conditions in combination with the respective fluid properties, especially gas solubility in released crude oil under high pressure, is crucial for both droplet formation at the wellhead and drop rise through the water column. A model for calculation of oil-droplet rise velocities under consideration of the pressure-dependent gas-in-oil solubility is presented and validated. For this purpose, the concept of “internal degassing” that leads to a higher buoyancy of crude-oil droplets and thus an accelerated drop rise is introduced. Calculation of three different drop-rise scenarios showed high impact of this effect. For the first time high-pressure experiments using gas-saturated crude oil and artificial seawater in a counter-current flow channel were conducted. Optical recording and analysis of droplet volume during pressure release confirm the significance of predicted effect of degassing. The interplay of degassing, nucleation, and mass transfer is discussed.

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Citation / Publisher Attribution

Environmental Engineering Science, v. 35, issue 4, p. 289-299