The Experimental And Theoretical Study On Flow Regimes Regime Transport Of Oil-gas In Horizontal Pipe

In oil industry, many countries have been developing the oil-gas transportation technology to satisfy the need of the project, and our country has already brought this technology into Hi-Tech Research and Development Program of China (863). As a typical two-phase flow problem, the key of this technology lies in the characteristics and the principle of the oil-gas flow. Two-phase flow widely exists in many industries such as chemical industry, metallurgical industry, energy industry and so on. The research on two-phase flow, which has been one of the frontier subjects concerned deeply in the world, is developing rapidly. The system of the oil-gas transportation, which is affected by the flux, the fluid physical properties, the geometry of the pipeline, the inclination angle and so on, makes the change of the void fraction, and shows different kinds of flow pattern. Slug flow is one of the most typical and common regimes of oil-gas two-phase flow through oil-gas transportation pipelines. This kind of intermittent flow would induce the liquid holdup and the pressure in the system to fluctuate. As the pipeline for oil-gas transportation is operated in this regime, an intense fluctuation of liquid level in oil-gas separators at downstream of the line would be caused when a liquid slug leaves the end of pipeline. A lot of accidents of the multiphase system are caused by the improper calculation and operation because of the unknown regimes. So it's very important to analyze the character of the regimes, especially the slug flow pattern, and to predict the regimes transition.This thesis expatiates a series of the relevant theoretical and experimental work for oil-gas two-phase flow in horizontal pipe. A two phase flows experimental platform was used to obtain experimental data.The working fluids are gas and diesel oil. During the experiment, the flux of the oil and gas were changed separately, and the flow pattern was observed from acrylic pipe.Smooth stratified flow,wave stratified flow, slug flow, were recognized. Then two flow pattern maps were gotten. In addition, pressure and differential pressure transducers and a data acquisition system were used to measure the pressure and differential pressure of the experimental pipeline . we can infer flow patterns by analysising experimental datas and drawing the corresponding power spectral density maps.In the research to the flow patterns transition. By using the classical Taitel & Dukler's semi-theoretical model and one-dimensional wave model, theoretical predictions of transition from stratified flow to slug flow were made. Based on the Kelvin-Helmholz wave theory, Taitel & Dukler semi-theoretical model analyzed the condition which tends to cause the wave to grow, and gives the expression of the condition. This condition was used as the theoretical criterion for transition from stratified flow to slug flow. The results of theoretical model compare well with the experimental data. But this model was based upon some assumptions, and the empiricism was embodied in the analysis. On the basic of One-dimensional theory, and according to therelationship of the continuity waves and the dynamic waves, One-dimensional wave model points out that instability results when the continuity waves overtake dynamicwaves. By using this conclusion, theoretical predictions of transition from stratified flow to slug flow were made. Good agreement has been achieved between predicted and measured results. So from the theoretical and the semi-theoretical formulas, the mechanism of stratified to slug flow transition was further studied.In this dissertation, the oil-gas flow patterns and flow pattern transition in horizontal pipelines and the effect factors were studied. Some important conclusions are obtained.