Design And Simulation Analysis Of Self-adaptive Plunger For Natural Gas Production

In the process of natural gas extraction,the bottom hole pressure is continuously reduced,and the bottom hole fluid is gradually generated.Downhole fluid accumulation will greatly reduce the production efficiency of Ryanran gas wells.Therefore,it is of great significance to study the drainage and gas recovery technology of natural gas wells for natural gas exploitation.In this paper,the structural design of the adaptive plunger,the design of the control system and the theoretical analysis of the motion process are carried out.In terms of plunger structure design,the bypass plunger has the characteristics of fast falling speed,low slip rate,and high reliability,so the bypass plunger is selected.In terms of control system design,the adaptive plunger uses sensors to measure temperature,pressure,and acceleration to determine whether the plunger has entered water,and then controls the plunger throttle valve to open and close.In terms of motion theory analysis,this article establishes two stages of plunger motion model: descending and ascending,and establishes the differential equation of plunger motion according to the force characteristics of the plunger at different stages,which provides a theoretical basis for the plunger motion relationship.In this paper,Fluent is used to conduct CFD analysis on the movement of the plunger to obtain the relationship between force,distance,speed,and time during the movement.When the plunger falls in the air,the speed rises rapidly from 0m/s to 30m/s,and then maintains a constant speed movement;when entering the water,the speed drops rapidly from 30m/s to 7.587m/s;after entering the water,the resistance of the water Under,the speed drops to 3.48m/s and then falls at a uniform speed.When the plunger reaches the specified depth,the valve is completely closed,and the plunger is hovered in the bottom fluid.During the upward movement,the amount of liquid discharged in a single operation and the speed of the plunger reaching the ground are positively related to the initial height of the lifting liquid column.Therefore,in order to ensure the efficiency of liquid drainage and the safety of the equipment on the well,in the Sulige gas field,the initial initial The height of the liquid lifting column is 190～270m.This article uses LS-DYNA to study the impact of plunger and tube wall high-speed collision on the plunger.Due to the scale attached to the pipe wall,the collision between the plunger and the pipe wall during the movement of the pipe wall can be considered as a collision problem with scale.Also,because the maximum deflection angle between the central axis of the plunger and the central axis of the pipe wall is,it can be approximated that the plunger falls vertically during the analysis.The analysis found that the impact of the plunger and the wall of the tube was directly related to the scale diameter and plunger speed.During the movement,the maximum impact force on the plunger is 605 MPa,which is lower than the maximum stress that 42 Cr Mo can bear,which can ensure that the plunger will not be damaged by impact.