Studies On The Models For The Low-Liquid-Loading Gas-Oil-Water Three Phase Flow In Near-Horizontal Pipes

Low-liquid-loading gas-oil-water flow, which exists widely in wet gas pipelines, is one of the typical occurrences of three-phase flow in the oil and gas industry. Wet gas transportation pipelines often contain water and hydrocarbon condensates, which lead to the occurrence of low-liquid-loading three-phase flow. However, small amounts of condensates can lead to a significant increase in pressure drop along a pipeline. In-situ liquid holdups are important factors for determining pigging frequency and designing receiving facilities. Accurate pressure gradient prediction is of great importance to select the right pipe size and material. Therefore, understanding of the flow characteristics of low-liquid-loading gas-oil- water flow is very important in the transportation of wet gas.For the low-liquid-loading gas-oil-water three phase flow in near horizontal pipes, this paper established a governing equations, based on the gas-oil-water momentum equation, for the calculation parametes of the governing equations, this paper gives the corresponding close relationships, so as to establish a complete model for the low-liquid-loading gas-oil-water three phase flow in near-horizontal pipes. As to the experimental observations for the low- liquid-loading gas-oil-water three phase flowpattern in near-horizontal pipes, analyze the flow characteristics of each flowpattern, which is proposed to divided flowpattern for the low- liquid-loading gas-oil-water three phase flow, by the gas-liquid flow type main, divided the oil-water flowpattern, and the corresponding criterion is given.With the experimental data, according to the established model for the low-liquid- loading gas-oil-water three phase flow in near-horizontal pipes to optimize the relationship of closure options, mainly for the gas-wall friction factor, gas–oil interfacial friction factor and gas-liquid interface shape screening or optimization. By comparative analysis, this paper established a new gas-oil interfacial friction factor combination relationship, while, for the application of gas-liquid interface shape gives the appropriate conclusions.By the comparative analysis of calculation model and experimental data, verify the proposed flowpattern criterion and analyze the distribution area of flowpattern. Model obtained liquid holdup and pressure gradient is validated. From the comparasive results, the model determines the flowpatterns more accurately, and the pressure gradient in etimating error is smaller, indicating the applicability of this model is well.In this paper, based on the model studies, but also analysis the operating parameters for the PuGuang gas field gathering and transportation pipelines, and according to the operating parameters of the first half of pigging cycle, which is validated, then the effect of field application for the calculate model are given the appropriate assessment, to illustrate the established model in practical applications has good reliability, can better predict the pressure drop for the practical engine.