Performance Analysis And Optimization Of Expanded Casing Threaded Joint

Expandable tubing technology has been used in the completion and work operations of oil drilling industry. Result in mostly failure of expansion pipes occurred on the threaded joints. With the increasing well depth of work operations, the existing expandable threaded joints have been unable to meet the more harsh operating conditions. Therefore, analysis of the mechanical properties of the expandable threaded joint and improve the mechanical properties of the joint have great significance to the widen use of Expandable tubing technology. Although designers did lots of research on connection strength and sealing performance of the joint, but mostly focused on ensuring the sealing performance of connector during the expansion, while ignoring the threaded connection after expansion, and did not consider the effect of expansion tool. Thus this paper proposes an evaluation method of the threaded joint performance, by analyzing the mechanical properties and the geometric deformation of the threaded joint during expansion. Combines numerical optimization methods which is based on mathematical programming theory with finite element methods, and using parametric modeling, approximate model and mesh deformation techniques, builds an optimization processes of threaded joint and mandrel. Replaces designers’experience by mathematical models for controlling of the joint and mandrel design direction, further improves joint performance. The analysis and optimize of the specific process and methods are as follows:(1) Establishes the finite element model of joint expanding process, and analyzes the mechanical properties and deformation during expansion, and proposes performance indexes and evaluation method of the threaded joint.(2) Builds the automatically calculates flow of parametric analysis of joint expanding. The sensitivity analysis of threaded joint parameters is researched through orthogonal design, the relationships between joint performances and joint structural parameters are achieved, and narrows the range of design variables. What is more, author carries out a multi-objective optimization of geometry on the joint to obtain the optimal size of the combination solutions.(3) Determines the initial model for the expanding mandrel optimization, by sensitivity analysis of mandrel parameters. And makes the mandrel boundary shape as the optimization object, optimizes it by morphing techniques and methods for the approximate model, achieving an optimum mandrel which can significantly improve the performance of joint.The methods and conclusions of this paper can provide designers a new way of analysis and optimization methods to improve the performance of expandable joint. Improves the performance of the expandable joint. It has a certain reference value to optimize the expandable threaded joint.