Experimental Study On Gas-Liquid Flowig In The Wellbore Of Horizontal Well

Due to large gas drainage area and fully reservoir reconstruction, horizontal well has been widely used in gas field. By using continuous liquid carrying fluid model, calculation of the critical flow rate of horizontal well is too high. The fundamental reason for inaccurate horizontal-well liquid-carrying prediction of existing model is that the horizontal well bore structure is complex, and the wellbore (especially the inclined section) in both liquid flow pattern and mechanism of theoretical research is not mature. In this paper, study of horizontal flow patterns and mechanism of horizontal well has been carried out, and the achievement are as follows.(1) The visual simulation experiment device of gas-water two phase flow has been developed, Which is6m vertically, and6m inclined, and10m horizontally(the adjustable inclined angle is between25°～72°). The device is able to capture microscopic characteristics in high speed flow condition. The physical simulation experimental environment has been established for the thesis study;(2) Under low fluid volume experiment, a new flow pattern has been found, which is oscillatory impingement flow. From the simulation experiment of horizontal well dynamic liquid carrying, oscillatory impingement flow shows a cyclical change regularly, which defined as a special kind of intermittent flow; Therefore the theory of oscillatory impingement liquid carrying in horizontal well has been established; Experiment observed the droplets can’t exist in long stability when in inclined segment. the liquid phase moving up mainly in the form of liquid film, which determines the volume of liquid carrying; The pressure gradient analysis show that, when the angle is about50°, liquid holdup comes to the largest;(3) Compare the result of horizontal gas well oscillatory impingement carrying and continuous liquid carrying test. Based on the experiments, the nature of the horizontal well liquid carrying has been revealed:liquid film carrying. The critical gas flow velocity is decreasing by the bottom hole pressure is increasing, while the critical gas flow is increasing. Considering the liquid film unequally distributed in the inclined tube. There is a ratio relationship between the critical gas flow rate of oscillatory impingement liquid carrying and the continuous liquid carrying critical gas flow rate, in which the ratio K is related to inclined angle. When the Angle is about50°, the K value reaches maximum;(4) With Paz inclined tube liquid film distribution model, the liquid holdup calculation method has been deduced, which leads to a new method to predict the liquid film carrying critical gas flow rate in inclined tube, and is verified by using the experimental test results. The results show that the accuracy of the new model is superior to other models; Verify the new model by using the date which is published by Belfroid, the error is13.7%. Verify the new model by using the experimental test results, the error is5.66%. The results show that the accuracy of the new model is superior to other models.A large number of case analyses of the DaNiuDi area in Ordos basin horizontal gas well have been carried out. Using the new method to forecast the critical liquid carrying flow rate of gas Wells, the correctness of oscillatory impingement liquid carrying theory is verified. Experiments above provide the theory and method in horizontal gas well study, which is of vital scientific significance and practical value in reasonable proration, liquid-carrying dynamic prediction and enhance oil recovery of horizontal gas well efficient recovery.