Simulation And Optimization Of Drainage Gas Recovery By Plunger Lift In Highly Deviated Wells

High-deviated wells have been widely used in gas reservoir development,but water production in gas wells will seriously affect their deliverability.Plunger lift,as a good lifting effect,simple process,low input cost of the drainage gas recovery process,has begun in the high deviated gas wells into use.At present,the plunger lift theory is based on the straight hole simulation experiment,it has great difference with the well trajectory of the high deviated well,does not consider the influence of the well angle on the plunger and its fluid flow pattern,and cannot be directly used in the plunger gas lifting process design of the high deviated well.To this end,this paper uses numerical simulation and physical simulation of the combination of technical routes,mainly to carry out the following work:(1)The velocity field and flow field distribution of fluid through rod plunger and tubing gap are calculated by fluent software and sensitivity analysis of groove,groove depth and groove width is made,and the optimal plunger structure parameters are selected and the plunger specimen is processed.(2)A visualized plunger lift simulation experiment device with arbitrary angle inclination is developed,the experimental device is composed of wellhead assembly,bottom hole assembly,tubing and casing string and other auxiliary devices,the total height is 10m,the casing with 120mm diameter and 62mm tubing are used,and the material is transparent Plexiglas tube.At the same time,it is equipped with gas-liquid supply system and measurement and control system,which lays the foundation for carrying out the simulation experiment of plunger lift drainage gas recovery in the high deviated well under different conditions.(3)Respectively in different gas flow,liquid flow,under the condition of shut-in time and well angle,the simulation experiment of plunger lift and conventional intermittent gas lift drainage gas recovery is carried out,and the difference of discharge efficiency under the same experimental condition is compared and analyzed,the experimental results show that the discharge efficiency of plunger lift process is higher than that of conventional intermittent gas lift.(4)The influence factors of the drainage efficiency of the plunger lift,the plunger rising height,plunger rising speed and plunger descent speed are analyzed in detail on the basis of the experimental phenomenon and data on flows of the well opening stage,the closing stage,plunger rising stage and the plunger down stage.(5)The research on the design method of plunger lift drainage gas recovery of high deviated well is carried out,the applicable conditions of plunger lift technology in high deviated wells are given from well angle,pressure,gas-liquid ratio,liquid production,pipe string and wellhead condition,and the calculation method of process parameters is put forward,and the calculation of the example well is carried out.The research in this paper greatly enriches the related theory of the plunger lift drainage gas recovery technology,and has important practical and guiding significance for the application of the plunger lift in the highly deviated wells.