Development And Structural Optimization Of Anti-high Pressure Gas Lift Valve

In gas lift production,gas lift valve is an important tool in gas production.It is mainly composed by case,bellows,seal,a single flow valve,valve ball,and valve body,and is a pressure regulator for downhole.When gas is collected,high pressure gas is injected into the casing through the gas lift valve,and the high-pressure gas is mixed with the liquid in the oil pipe to reduce the density of the crude oil or the gas containing liquid,to achieve the purpose of gas lift production and liquid discharge.At present,the gas lift valve used in the field is the method of an internal pressure of 25MPa.With the increase of deep gas wells in the Sichuan gas field(especially in eastern Sichuan),deep sea oil wells and Xinjiang oil fields,gas lift valves are used for wells with a depth of more than 6,000 meters.In deep wells,its sealing performance and compressive strength are not up to the requirements of field use.When the casing pressure is restored to 30MPa,the gas lift valve is not allowed to open under this pressure.However,the method of ensuring that the gas lift valve is not opened is to increase the chargeable pressure in the gas lift valve to about 35MPa.Therefore,it is necessary to develop a new type of anti-high-pressure gas lift valve to make it better and faster to discharge downhole liquid.Based on the structural characteristics of the 25MPa gas lift valve,finite element values are used.The combination of analysis and test verification methods for the development and optimization of a new gas pressure valve structure resistant to 35MPa internal pressure is as follows:(1)Investigated the research status of gas lift valves by domestic and foreign scholars,analysed the research results of gas lift valves,to propose a new anti-high-pressure gas lift valve.(2)Analysed the composition of the gas lift valve and its working characteristics as well as the failure mode of the gas lift valve,conduct mechanical theory research on the main failure components.To establish the calculation formula of the bellows stiffness and stress,the valve seat valve ball of the contact stress calculation formula and the contact theory formula of the rubber seal structure in the gas lift valve.(3)Established the finite element simplified model of the bellows of the gas lift valve.The compressive strength and stiffness of the bellows of the gas lift valve are the structural performance evaluation criteria.The parameters of the bellows of different gas lift valves are analysed under the combined action of internal and external pressure.The axial elastic stiffness and stress of the bellows are then combined with the conditions of use of the gas lift valve and the material properties to select the optimum dimensional parameters.(4)The finite element model of the single-flow valve assembly of the gas lift valve is established.The influence of the shape of the single-flow valve body seal groove,the chamfer size and the friction coefficient on the sealing performance of the single-flow valve assembly is analysed.(5)Using ABAQUS finite element analysis software and FEMFAT fatigue analysis software to analyse the structural optimization and to improve its stress distribution and improve its compressive performance.(6)Successfully developed a new type of anti-high-pressure gas lift valve.The new one was tested for bellows chamber strength,gas lift valve opening performance test,gas lift valve aging test,aging The rear gas lift valve is opened for pressure performance test,and the single flow valve is resistant to water pressure test to verify whether the new high pressure gas lift valve is qualified.Through the finite element analysis,to investigate the influence of the parameters of the gas lift valve on the performance of the gas lift valve,which has important reference significance for the development of anti-high pressure gas lift valve.