Bubble Sizes, Breakup, and Coalescence in Deepwater Gas/Oil Plumes

Abstract

Bubble size distribution (BSD) plays a major role in transport and fate of gas or oil released in deepwater. However, no reliable method is available to estimate gas or oil BSD after a deepwater spill. Breakup and coalescence have been identified as key processes controlling BSDs in turbulent jets. The present work introduces bubble breakup and coalescence processes for deepwater gas or oil spill models. A population balance equation representing bubble volumes is used to model the evolution of bubble sizes caused by breakup and coalescence. Existing theories for bubble breakup and coalescence rates in bubble columns are adopted to deepwater plumes. The advantage of the present model is that the BSD is generated as a result of breakup and coalescence; and therefore, a predefined BSD is no longer necessary for simulations. The comparison of model-computed results with laboratory and field data shows a good agreement. Scenario simulations show that the seed diameter given to start computations affects only for a short distance from the release point. Simulations also show that bubble breakup and coalescence is important only during the early stages of the plume where turbulence is dominant. The importance of accounting for gas bubble breakup and coalescence in estimation of gas dissolution is also demonstrated.