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5.1 Introduction
The rise behavior of oil droplets and natural gas bubbles is of major importance for
understanding the physical behavior of dispersed oil in the aftermath of a deep-sea
blowout. It is also indispensable for the development and adjustment of oil fate
modeling tools that estimate the subsea distribution of oil masses. So far, to estimate
the oil distribution throughout the water column and the expected surfacing times, a
couple of well-known correlations for the calculation of the rise velocities of single
particles with fluidic interfaces in stagnant media are available from process engineering applications. Besides the physical properties of live oil under environmental
conditions, the size of the gas bubbles and oil droplets are the most crucial parameters that determine rise velocities.
However, the distribution and fate of oil, thoroughly discussed in the third section of this book (Part III: Transport and Degradation of Oil and Gas from Deep
Spills), are much more complicated than just calculating the rise velocities of single
particles of a given size and composition. Swarm effects within the multiphase
plume, ocean currents that transport the hydrocarbon mixture horizontally, gas
hydrate formation due to the high-pressure low-temperature conditions in the deep
sea, and the partitioning of certain oil components affect the oil distribution and
render the modeling of the oil fate extremely challenging. The buoyancy-driven
ascent of the bubbles and droplets forms the basis for any oil spill modeling. In this
chapter, we investigate and discuss the rise behavior of fluid particles in realistic
oil-gas-seawater mixtures under deep-sea conditions.
5.2 Correlations for the Rise Velocity of Single Fluid
Particles
The most important parameters that influence the rise velocity u p of buoyant particles (i.e., gas bubbles and oil droplets) are the density of both the ambient seawater
(continuous aqueous phase) and the oil and/or gas (dispersed phase) as well as the
median particle diameter d p of the particle size distribution in oil and gas plumes
(described in Chap. 4). The difference between the density of the continuous aqueous phase ρ c and the density of the dispersed oil or gas phase ρ d defines the driving
gradient for the buoyant ascent of the fluid particles. Other important physical properties influencing the rise velocity are the dynamic viscosity of the continuous phase
μ c and the interfacial tension between the continuous and the dispersed phase σ,
determining the interaction between the phases and the size-dependent particle’s
shape. These thermodynamic properties depend on water depth (i.e., pressure and
temperature) and on the exact composition and mutual solubility of the oil and gas
that also vary with the ambient pressure and temperature. An extensive overview on
experimental and modeling results of physical properties and gas-in-oil solubility
under simulated reservoir and deep-sea conditions can be found in Chap. 3.
S. Pesch et al.
5.1 Introduction
The rise behavior of oil droplets and natural gas bubbles is of major importance for
understanding the physical behavior of dispersed oil in the aftermath of a deep-sea
blowout. It is also indispensable for the development and adjustment of oil fate
modeling tools that estimate the subsea distribution of oil masses. So far, to estimate
the oil distribution throughout the water column and the expected surfacing times, a
couple of well-known correlations for the calculation of the rise velocities of single
particles with fluidic interfaces in stagnant media are available from process engineering applications. Besides the physical properties of live oil under environmental
conditions, the size of the gas bubbles and oil droplets are the most crucial parameters that determine rise velocities.
However, the distribution and fate of oil, thoroughly discussed in the third section of this book (Part III: Transport and Degradation of Oil and Gas from Deep
Spills), are much more complicated than just calculating the rise velocities of single
particles of a given size and composition. Swarm effects within the multiphase
plume, ocean currents that transport the hydrocarbon mixture horizontally, gas
hydrate formation due to the high-pressure low-temperature conditions in the deep
sea, and the partitioning of certain oil components affect the oil distribution and
render the modeling of the oil fate extremely challenging. The buoyancy-driven
ascent of the bubbles and droplets forms the basis for any oil spill modeling. In this
chapter, we investigate and discuss the rise behavior of fluid particles in realistic
oil-gas-seawater mixtures under deep-sea conditions.
5.2 Correlations for the Rise Velocity of Single Fluid
Particles
The most important parameters that influence the rise velocity u p of buoyant particles (i.e., gas bubbles and oil droplets) are the density of both the ambient seawater
(continuous aqueous phase) and the oil and/or gas (dispersed phase) as well as the
median particle diameter d p of the particle size distribution in oil and gas plumes
(described in Chap. 4). The difference between the density of the continuous aqueous phase ρ c and the density of the dispersed oil or gas phase ρ d defines the driving
gradient for the buoyant ascent of the fluid particles. Other important physical properties influencing the rise velocity are the dynamic viscosity of the continuous phase
μ c and the interfacial tension between the continuous and the dispersed phase σ,
determining the interaction between the phases and the size-dependent particle’s
shape. These thermodynamic properties depend on water depth (i.e., pressure and
temperature) and on the exact composition and mutual solubility of the oil and gas
that also vary with the ambient pressure and temperature. An extensive overview on
experimental and modeling results of physical properties and gas-in-oil solubility
under simulated reservoir and deep-sea conditions can be found in Chap. 3.
S. Pesch et al.