Influência do vazamento no transporte de óleos pesados via core-flow em tubulação com um trecho curvado: modelagem e simulação.

Abstract

Heavy oils constitute a large part of the accessible national and world reserve, to be explored and produced. However, its high degree of density and viscosity, in addition to its physicochemical properties and its high content of naphthenic acids, make the production costs of this type of oil

quite high. A method that has enabled the production and transport of this type of oil is the core- flow technique, which consists of injecting water into an oil stream, causing the water to lubricate

an oil core and, thus, establishing an annular pattern. This will lead to a decrease in the high- pressure drop observed in the transport of heavy oils, since the friction losses are comparable to

the losses observed when the water flows alone in the pipeline. However, as in any other means of transport, pipes are subject to mechanical and operational failures, corrosion, natural accidents, among other factors that lead to leaks of different sizes in pipes. The occurrence of leaks is responsible for most accidents in pipelines. In this sense, the objective of this study is to contribute to the understanding of the phenomena involved in the transport of heavy oils using the core-flow technique with and without leakage. The computational modeling was performed by the software ANSYS FLUENT through the finite volume method, in two curved ducts with radii of curvature of 0.2 and 0.4 m with and without leakage. The mathematical modeling used was the Volume of Fluids (VOF), using the standard k- turbulence model, in a transient regime, considering the gravitational force. The results of the volumetric fraction, pressure and velocity fields were presented and discussed. Based on these parameters, it can be concluded that the core-flow pattern can be undone due to the effect of curvature and that the presence of leakage causes the heavy oil to adhere to the pipe wall.