The paper presents the study results of intermittent gaslift. vertical flows using both experiment and theoretical models. To study the influence of medium thermophysical characteristics on the process efficiency, two gas-liquid systems arc used in the experiments. | Vietnam Journal of Mechanics, VAST, Vol. 29, No. 3 (2007) , pp. 321 335 Special Issue Dedicated to the Memory of Prof. Nguyen Van Dao INTERMITTENT GASLIFT FLOWS IN VERTICAL PIPES DUONG NGOC HAI Institute of Mechanics, VAST NGUYEN THUC KIIANG Oil-Gas Joint Venture Vietsovpetro NGUYEN DUY THIEN Electr'ic Power University Abstract. The paper presents the study results of intermittent gaslift. vertical flows using both experiment and theoretical models. To study the influence of rncdium thcrmophysical characteristics on the process efficiency, two gas-liquid systems arc used in the experiments. The obtained results show that there is a critical gas injection volume, less than that the liquid slug cannot reach the top of the tubing. Correlations for prediction of liquid entrainment in gas core are also shown for two presented gas-liquid systems. A modified dynamical model was developed. The model consists of a system of' differential equations. The resulting system of equations is numerically solved. The numerical code is verified by using experimental data and calculation data of the other authors. Finally, the effects of system parameters are studied. Keywords: intermittent gaslift, liquid-gas flows, liquid slug, physical and theoretical models, efficiency. 1. INTRODUCTION A big part of all oil wells in the world is being produced using gaslift technique. Gaslift , known as continuous and intermittent lift, is realized by the injection of high pressure gas in a well, in order to create the necessary flowing bottomhole pressure to produce the desired rate of crude oil. Continuous gaslift is a direct extension of naturnl flow , and is accomplished by the constant gas injection at the deepest possible point in order to create the rising hydrocarbon stream. This results in reducing flowing bottomhole pressure and increasing flow from the reservoir. Few works has been published on the intermittent gaslift. Brill et al. ( 19G7) reported the results of a wide range of
