Calculating densities and viscosities of natural gas with a high content of C2+ to predict two-phase liquid-gas flow pattern

Abstract

The paper is devoted to the two-phase flow simulation. The gas-condensate mixture flow in a horizontal pipe under high pressure is considered. The influence of the equation of state (EOS) choice for mixture properties modelling on the flow regime calculation results is studied for gas with high content of methane homologues. An analytical overview of the methods to predict the flow pattern is provided. Based on this analysis, two techniques are selected. For these techniques, values of density and viscosity for each phase are required. Density calculation for the gas phase is performed with Van der Waals based EOS. The propriate EOS is selected based on studies of calculation errors for test mixtures. Calculation of liquid phase density is done by means of Patela-Teja and Guo-Du equations, two different models are considered for viscosity estimation. The flow patterns of gas-condensate mixture in a range of temperatures and pressures are calculated and verified via probability map. The results of study allow to recommend the Brusilovsky EOS for calculation of densities for similar gas mixtures and make more rigorous flow regime evaluation. The probability map shows that for the chosen composition and parameters of media the flow pattern is mostly transitional between segregated and annular independent from EOS.