Influence of the characteristics of an annular dispersed flow on the behaviour of a Venturi meter

摘要

This work is included in an overall study linked to the production of gas from high pressure natural reservoirs. During the extraction of the gas, a liquid phase appears as condensates and water. In many applications the gas volume fraction (GVF) is high and the flow can be considered as a wet gas. The exact metering of the extracted gas necessitates a previous gas/liquid separation. In order to diminish the costs, another solution is to count the whole flow with a unique flow meter. Among the different methods on the market, the Venturi meter is nowadays still widespread. Different empirical correlations based on a Lockhart Martinelli parameter were proposed to take into account the liquid phase, in the gas flow rate measurement. Nevertheless the accuracy of these correlations is not sufficient for allocation or reservoir monitoring. In fact these correlations do not take into account the influence of the two phase flow characteristics in the pipe upstream of the flow meter. To improve the metering method, a research program based on numerical and experimental tests has been developed by Total, Gaz de France and ONERA. In this paper we will present experimental results on the influence of the characteristics of the two phase flow upstream of the Venturi meter on the ΔP. During these tests, different pipe orientations are tested. The two phase flow characteristics (droplet size, flow rate and thickness of the film, wave amplitude and wavelength of the film disturbances) are measured. The ΔP measurements indicate that for a same Lockhart Martinelli parameter, the characteristics of the two phase flow have a great influence on the correlation coefficient. A first analysis is presented in order to determine among the two phase flow characteristics, those which influence greatly the ΔP deviations.