Simulação fluidodinâmica da dispersão de petróleo a partir do vazamento em riser submerso sob efeitos dinâmicos e estáticos.

Abstract

Great are the economic and environmental losses caused by accidents due to oil spills at sea. When this type of situation occurs, speed and efficiency in the emergency response process become necessary to remedy this situation. There are many works in the literature that present studies of petroleum spills in shallow waters arising from ruptures in pipelines. However, several works that involve studies on risers deal only with the internal flow and/or the mechanics of the riser and do not study the external flow. Studies involving oil leakage from damaged pipelines under static effect are found in the literature, however, no work was found that deals with oil leakage from a moving riser, through Computational Fluid Dynamics (CFD). Therefore, it is extremely important to study the physical behavior, trajectory, and propagation time that petroleum takes to move from the leak point to the free surface using a moving riser via CFD, since several factors can cause the formation of a leak in a riser, for example, the type of material, the number of layers of the riser, the lifetime, environmental conditions, density of internal and external fluids, pressure of the internal fluid, corrosion, static load due to the riser's own weight, chemical effects of seawater and other chemical components that accompany the petroleum throughout the production process, riser fatigue and even the assembly, installation and operation of the risers can cause their rupture, resulting in a great financial and environmental loss. Thus, it was decided to study the petroleum dispersion from the leak in flexible risers subjected to static and dynamic effects. Upon the above, a numerical study was performed using Ansys Fluent 2020 to evaluate oil dispersion based on the effects of current velocity, oil density, water density, oil viscosity, leak velocity, and leak diameter using the multiphase model Volume of Fluid – VOF, where the standard k-ε turbulence model was inserted to describe the multiphase flow. The dynamic mesh method was used to implement the static and movement effect of the riser using a subroutine to promote the riser movement with displacement values proportional to each current velocity adopted. Therefore, the main purpose of this work is to study the petroleum dispersion from leakage in a submerged riser under dynamic and static effects. Thus, through the results of pressure field, water surface velocity, volumetric fraction, height, and distance covered by the leaked oil plume, it was possible to evaluate the underwater dispersion of the oil plume in water with dynamic and static mobility.