Flow pattern and pressure drop in horizontal viscous oil-water flows

Abstract

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.

Despite recent discoveries of light oil in the Brazil's pre-salt layer, about 25% of its' reserves will still consist of viscous oil. In the case of light oil, commercial software are able to provide, with an admissible uncertainty, pressure drop and holdup of oil-water flows, however when they are used for the same flow predictions involving viscous oils there is a large discrepancy between the experimental data and predictions. In this work, experimental data of pressure gradient, characterization of flow patterns in horizontal viscous oil-water flows and spatial transition of the stratified flow to intermittent flow were acquired at the experimental facility of the LETeF (Thermal and Fluids Engineering Laboratory) of the Engineering School of Sao Carlos of the University of Sao Paulo in Brazil. The experimental facility consists of 12 m length glass pipeline of 26 mm i.d. It is equipped with positive displacement pumps and volumetric flow meters for oil and water. Oil with viscosity of 300 mPa.s and density of 845 kg/m³ at 20°C and tap water were the working fluids. A high speed camera was used to film the flow and characterize flow patterns. The movies were taken at transparent sections placed at the pipeline filled with water to reduce distortion effects. The observed flow patterns were: smooth stratified, wavy stratified, stratified with mixture at the interface, drops of oil in water, plug flow (intermittent flow), core-annular flow, and dispersion of oil in water. The pressure drop was measured using a high speed differential pressure transducer from Validyne™. It was observed that as the flow pattern changes, the behaviour of the variation of the pressure drop also changes. The experimental data are being used to improve the two-phase flows models, e.g. the one dimensional two-fluid model.