Eduardo Pereyra

Bio: Eduardo Pereyra is an academic researcher from University of Tulsa. The author has contributed to research in topics: Slug flow & Two-phase flow. The author has an hindex of 18, co-authored 137 publications receiving 1163 citations. Previous affiliations of Eduardo Pereyra include PDVSA.

An Efficient Drift-Flux Closure Relationship to Estimate Liquid Holdups of Gas-Liquid Two-Phase Flow in Pipes

Abstract: The reliable predictions of liquid holdup and pressure drop are essential for pipeline design in oil and gas industry. In this study, the drift-flux approach is utilized to calculate liquid holdups. This approach has been widely used in formulation of the basic equations for multiphase flow in pipelines. Most of the drift-flux models have been developed on an empirical basis from the experimental data. Even though, previous studies showed that these models can be applied to different flow pattern and pipe inclination, when the distribution parameter is flow pattern dependent. They are limited to a set of fluid properties, pipe geometries and operational conditions. The objective of this study is to develop a new drift-flux closure relationship for prediction of liquid holdups in pipes that can be easily applied to a wide range of flow conditions. The developed correlation is compared with nine available correlations from literatures, and validated using the TUFFP (Fluid Flow Projects of University of Tulsa) experimental datasets and OLGA (OiL and GAs simulator supplied by SPTgroup) steady-state synthetic data generated by OLGA Multiphase Toolkit. The developed correlation performs better in predicting liquid holdups than the available correlations for a wide range of flow conditions.

Pipe-Diameter Effect on Liquid Loading in Vertical Gas Wells

Abstract: The effect of pipe diameter on liquid-loading initiation has been investigated experimentally with pipes having internal diameters of 5.1(2-) and 10.2-cm (4-in.). Two-phase-flow parameters, such as pressure gradient and liquid holdup, were measured. Flow characteristics were determined by visual observation with a high-speed video camera. Critical gas-flow rate for liquid-loading initiation was identified, and comparisons between the two pipe diameters were presented. The critical superficial-gas velocity corresponding to the minimum pressure gradient was found to be faster for the smaller diameter. When the comparison was carried out in terms of mass-flow rates, critical flow rate for liquid loading in a 5.1-cm (2-in.) pipe was less than that in a 10.2-cm (4-in.) pipe. This verifies the use of velocity strings to extend the production life of the gas wells. Additionally, comparison of the data with available mechanistic-models prediction showed significant discrepancies. Possible reasons for these discrepancies are discussed.

A Review of Experiments and Modeling of Gas-Liquid Flow in Electrical Submersible Pumps

Abstract: As the second most widely used artificial lift method in petroleum production (and first in produced amount), electrical submersible pump (ESP) maintains or increases flow rate by converting kinetic energy to hydraulic pressure of hydrocarbon fluids. To facilitate its optimal working conditions, an ESP has to be operated within a narrow application window. Issues like gas involvement, changing production rate and high oil viscosity, greatly impede ESP boosting pressure. Previous experimental studies showed that the presence of gas would cause ESP hydraulic head degradation. The flow behaviors inside ESPs under gassy conditions, such as pressure surging and gas pockets, further deteriorate ESP pressure boosting ability. Therefore, it is important to know what parameters govern the gas-liquid flow structure inside a rotating ESP and how it can be modeled. This paper presents a comprehensive review on the key factors that affect ESP performance under gassy flow conditions. Furthermore, the empirical and mechanistic models for predicting ESP pressure increment are discussed. The computational fluid dynamics (CFD)-based modeling approach for studying the multiphase flow in a rotating ESP is explained as well. The closure relationships that are critical to both mechanistic and numerical models are reviewed, which are helpful for further development of more accurate models for predicting ESP gas-liquid flow behaviors.