A new model for predicting gas-liquid two-phase choke flow considering the slip

The accurate prediction on the ability of choke to allow gas/liquid mixture to fow through it is fundamental for the design of downhole or surface throttle process of oil and gas wells. And gas-liquid two-phase choke fow model is extensively applied in oil and gas production process. A new model for predicting the mass velocity of gas-liquid two-phase choke fow was established according to the principle of conservation of momentum based on the concepts of equivalent momentum specifc volume and equivalent kinetic velocity, combined with gas-liquid slip ratio, and its numerical solution algorithm was worked out. Compared with four other models, this new model is simpler and more convenient. Then, the accuracy of this newly built model and four commonly used two-phase choke fow models was evaluated by using the published experimental data of subcritical fow and critical fow. It is shown that this new modelis much superior to Sachdeva, Perkins, Ashford & Pierce and Al-safran models. Its average error of mass velocity prediction capacity is 1.37%, average absolute error is 6.37% and standard deviation is 5.79%. And its average error of pressure prediction capacity before the choke is 2.78%, average absolute error is 8.43% and standard deviation is 4.10%. The accuracy of this new model is affected by gas-liquid two-phase slip ratio calculation methods. Therefore, 9 methods for calculating gas-liquid two-phase slip ratio were comparatively analyzed in this paper. It is indicated that the prediction value is the closest to the experimental result when this model is combined with Chisholm slip ratio calculation method. And fnally, a certain water producing gas well was taken as the example to calculate the choke diameter of downhole throttle process. And the proration ratio of the choke diameter which is designed based on this new model is 96.5%.