关键词: 柱塞, 气举工艺, 控制体, 气体压力, 动态模型

Abstract: In order to study gas pressure variety and plunger movement during plunger lifting,the circulate cycle of plunger was divided into three continuous stages of upward travel of plunger,opening of sales valve after plunger arrived,falling of plunger and resuming of pressure.The movement features of plunger and liquid column were studied by using the momentum conservation equation.The change of gas pressure during movement of plunger was investigated with the mass conservation law.The gas pressures in the upper and below parts of plunger were discussed,in consideration of the effects of gas came from gas reservoir and output from well bore in the gas expanding equation and the effects of liquid loading in well bore on gas production of a gas reservoir.When the mass conservation law was utilized to establish theoretical models,the gas volume in the studied section was divided into a lot of control volumes,and the factors of controlled volume were assumed as invariable with time increment.A lot of movement equations for plunger and liquid column were given,and the dynamic models for calculating casing pressure and tubing pressure were established on the analysis of different factors.The calculation procedures of the models were accomplished.The case history computation in-situ approves that the model has good dependability and can provide a theoretical base for optimum design of plunger gas lift.

Key words: plunger, gas lift technology, control volume, gas pressure, dynamic model