Performance Analysis And Structure Optimization Of Collet Downhole Choke

Downhole throttling technology is widely used in various large gas fields for the purpose of realizing natural gas throttling and pressure reduction.Downhole choke is a key component to realize the throttling and pressure reduction process.There are many structures and types.Among them,the claw-type throttle is used to pre-compress the claws of the throw-away tube for delivery operations.It has the advantages of easy disengagement,anti-slipping,and no oil pipe seizure.It has been put into production in the Sulige gas field in a small scale.The initial application effect is good,but in actual Some gas wells in the application have problems such as the inability of the choke to work normally and the difficulty of salvaging.With the support of the project commissioned by Petro China Changqing Oilfield,this paper takes the claw-type downhole choke as the research object,and through performance analysis and structural optimization under the axiom design theory and framework,it is found that there are problems in the use of the structure of the choke.Provide theoretical basis and reference for the solution and further promotion and application.The main research contents include:(1)Carry out three-dimensional modeling of the claw-type downhole choke and analyze its working principle and process,and summarize the structural characteristics of the device.(2)Combine the axiomatic design theory method with the performance analysis and optimization process of the throttle,establish the axiomatic model and get the optimization flowchart,so as to ensure the logic and rationality of the analysis and optimization process.(3)Under the established axiom design optimization framework,the finite element method is used to model and solve the setting and unsealing system of the device.Firstly,the controlled variable method is adopted,and the length of the claw rod,the thickness of the rod,the tooth height and the forming angle are used as design variables to study the influence of parameter changes on the working performance of the device,and obtain the optimization range of the influence parameters,which lays the foundation for subsequent research.The response surface optimization method is adopted to ensure that the device can be locked normally,the four structural parameters of the claws are used as design variables,and the obtained optimization range is used as the constraint condition to minimize the contact stress under the state of launching and fishing.In order to optimize the goal,the optimal combination of structural parameters is obtained.(4)The technical adaptability analysis and evaluation of the optimization results show that the optimization results based on the axiomatic optimization process can be used as a reference for the performance optimization of the existing collet downhole choke devices.