Numerical models to simulate oil and gas blowout plumes and associated chemical and physical processes of hydrocarbons

Anusha Dissanayake, Inok Jun, Scott Socolofsky

Thursday 2 july 2015

14:40 - 15:00h at Europe 1 (level 0)

Themes: (T) Special session, (ST) Oil spill modelling

Parallel session: 12J. Special session: Oli Spill Modelling

In this paper, we present an integral plume-modeling suite that is developed to simulate multiphase oil and gas blowout plumes and demonstrate the model validations against laboratory and field data. The modeling suite is capable of simulating plumes formed in both stratification-dominant (Stratified Plume Model) and ambient current-dominant (Bent Plume Model) environments, along with hydrodynamic, chemical, and thermodynamic processes of hydrocarbons. The fate of these hydrocarbons released as plumes significantly depends on their rise velocity, mass transfer rates, and induced plume velocities. However, especially in the deep ocean, physical and chemical parameters of the gas bubbles are potentially affected by the formation of clathrate hydrate shells around them, yielding unknown mass transfer effects. Hydrate shells can stop the fluid circulation within a bubble and interfere in the mass transfer between the bubble and ambient. During the model calibration for the bubble dissolution rate, we found that the transition of a bubble status from clean to dirty in the ocean depends on the initial bubble size, and hydrate kinetics could accelerate this transition time at high levels of subcooling. But, hydrate skins generally do not inhibit mass transfer below standard values for contaminated interfaces. The stratified and bent plume models are developed based on the Eulerian double-plume model theory and Lagrangian approach, respectively. The plume models are capable of simulating the size distributions of the dispersed phases and their separation from the main plume in high cross flow conditions. These models can predict the distribution of oil/gas in the water column along with their approximate surfacing volume, time, and location with respect to the plume release point. These parameters are important for contingency planning and response to accidental under water oil/gas spills.