Hydraulic calculation model of low holdup wet natural gas transmission pipeline

Compared with the common oil-gas-water three-phase flow, low holdup three-phase flow has its special flow characteristic due to lowest liquid content which brings more difficulties for predicting the holdup and pressure drop. Aiming at the transmission characteristic of low holdup wet natural gas and based on the basic principle of hydromechanics, the model to predict the holdup and pressure drop for oil-gas-water three-phase flow of pipeline is established. The model simplifies the empirical relations about the wet-wall fraction, liquid-wall friction factor, interfacial friction factor and oil-gas mix viscosity. The model presents the speed judging condition of the gas taken by the liquid based on the low holdup liquid flow characteristic. The model considers the nonhorizontal gas-liquid interface and presents the curved surface processing method. The calculation result agrees well with that of in laboratory, which shows that the model is appropriate for predicting the holdup and pressure drop of pipeline and can provide an effective instruction in design and operation of low holdup wet gas pipeline.