Evaluation of Twophase Flow Correlations and Mechanistic Models for Pipelines at Horizontal and Inclined Upward Flow

Abstract

Abstract In this study, commonly used two-phase flow pressure prediction correlations and mechanistic models for pipelines in petroleum industry are evaluated against experimental data. The experimental data were obtained from published papers. Horizontal and upward two-phase flow are common in oil and gas production and transportation. During pipeline design and simulation, experimental data are usually unavailable to calibrate against correlations and models. In this situation, it is difficult to determine which correlation or model to use in predicting pressure gradient in pipelines. Experimental data used in this study are from Kokal and Stanislav papers (Kokal and Stanislav, 1989) and from Chen et al. paper (Chen et al., 1997). For the Kokal and Stanislav papers, experimental data were gathered from 1-inch, 2-inch and 3- inch pipes with seven inclination angles. Oil and air were used as testing fluids. During the experiment, superficial liquid velocities range from 1.2 to 10 ft/s and superficial gas velocities range from 0.76 to 85 ft/s. For the Chen et al. paper, data were gathered from a 3-inch horizontal pipe at stratified-wavy flow. Kerosene and air were testing fluids. Beggs-Brill, Dukler-Eaton-Flanigan, Dukler and Eaton correlations and Xiao mechanistic model are evaluated in this study. The results of this study can be used as guidelines in choosing two-phase flow pressure prediction correlations and models in designing and analyzing horizontal and upward two-phase flow pipelines. Introduction Horizontal and upward two-phase pipe flow is a common occurrence in oil and gas production and transportation. Although there are many pipeline correlations and mechanistic models around, during pipeline design and simulation, it is often difficult to determine which correlation or mechanistic model to use since correlations and mechanistic models were developed under specific conditions. Correlations and mechanistic models evaluated in this study include Beggs-Brill (BB), Dukler-Eaton-Flanigan (DEF), Dukler (D), Eaton (E) and Xiao (Xiao). Below is a brief description of the correlations and Xiao Mechanistic model (Yuan and Zhou, 2008). The Beggs-Brill correlation was developed from experimental data obtained in a small scale test facility. The facility consisted of 1-inch and 1.5-inch sections of acrylic pipe 90 ft long. Fluids used were air and water. The correlations were developed from 584 measured tests for all inclination angles (Brill and Beggs, 1991). The Eaton correlation was developed from experimental data obtained from a flow system consisting of 2-inch and 4-inch horizontal lines. Correlations were for liquid holdup and two-phase friction factor (Brill and Beggs, 1991). The Dukler correlation was based on similarity analysis and the friction factor and liquid hold up correlations were developed from field data (Brill and Beggs, 1991). The Dukler-Eaton-Flanigan correlation uses Dukler correlation for friction calculation, Eaton correlation for liquid holdup calculation (Pipesoft-2TM Manual 2, 2007). The Xiao model is a comprehensive mechanistic model developed for gas-liquid two-phase flow in horizontal and near horizontal pipelines. It has been evaluated against a data bank that includes field data culled from the A. G. A. database, and laboratory data published in the literature (Xiao et al., 1990). In this study, above mentioned four correlations and one mechanistic model are evaluated against measured data from published papers to determine which correlations or model behave better at various pipe diameters, superficial velocities and inclination angles.