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

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.cf201

Analytical model for interfacial waves in vertical core flow

The vertical annular pipe flow of two immiscible liquids with very different viscosities provides an efficient and low cost method for producing heavy oils in vertical wells using water as a lubricant. The core flow pattern is becoming attractive in the current Brazilian deep water production scenario. Understanding interfacial phenomena present in this flow pattern is crucial for appropriate design of the production system. Assuming that in this axisymmetric flow there is no net force associated with interfacial tension, a differential equation governing the shape of the liquid-liquid interface is derived. An analytical solution is proposed for the prediction of the wave geometry, which depends only on pipe geometry, physical properties and flow rates of the fluids. The comparison between the model predictions and recent experimental data shows a reasonable agreement. (c) 2006 Elsevier B.V. All rights reserved.544173217318

Heat recovery from hot solid particles in a shallow fluidized bed

A heat exchanger with a shallow gas-solid fluidized bed was experimentally studied in order to analyze energy recovery from solid particles leaving a combustion process. The experiments were carried out with and without vertical baffles in a fluidized bed with immersed horizontal tubes filled with water, in a counter flow arrangement. Two particle diameters (254 and 385 mum), two solid flow rates (50 and 80 kg/h) and two gas flow rates (46 and 50 kg/h) were tested, The bed temperature along the equipment length, the mass flow rate and the inlet and outlet temperatures of solid particles, air and water were measured in order to obtain the bed-tube heat transfer coefficient and the heat exchanger effectiveness. An increment of about 55% in the heat transfer coefficient and higher values of the heat exchanger effectiveness, in experiments with the presence of baffles, was verified. The experimental results also showed that the suspension-wall heat transfer coefficient increased considerably with the solid flow rate and also when the particle diameter decreased. (C) 2001 Elsevier Science Ltd. All rights reserved.22214516

Experimental investigation on liquid-liquid-gas flow: Flow patterns and pressure-gradient

The use of core-annular flow pattern, where a thin fluid surrounds a viscous one, may be attractive to heavy oil transportation and as an artificial lifting method in heavy oil wells,a situation that can become frequent in the Brazilian offshore scenario. However, in petroleum production, operations gas is frequently present. Therefore, the study of three-phase flow of heavy oil, water and gas is in order. This paper reports pressure drop measurements and three-phase flow patterns observed in horizontal and vertical 2.84-cm W. glass pipes. The focus was a mixture of heavy crude oil (3400 mPa s, 970 kg/m(3) at 20 degrees C), water an air at several combinations of the individual flow rates. Three-phase pressure drop data were compared with single-phase oil and two-phase oil-gas flows to assess the gains due to water injection. In addition. three-phase flow patterns formed inside vertical and slightly inclined 1.0 cm i.d. pipes,are also presented. Thus, scale-up and inclination effects could be qualitatively analyzed. Full-scale onshore-field experiments were conducted in order to investigate the applicability of using water to transport heavy oil in actual lines in the presence of gas. A big steel pipeline (7.7 cm W. and 274 m) conveying a very viscous crude oil (36950 mPa s, 972.1 kg/m(3) at 20 degrees C), natural gas (GOR 15 m(3)/m(3)) and water was used. Onshore-field three-phase flow tests were carried out and pressure gradient data are reported. The observed improvements in oil production rates and the pressure drop reductions obtained are remarkable. (c) 2009 Elsevier B.V. All rights reserved.6541671113ANPFINEPPETROBRA