Research And Simulation Analysis Of Two-way Jar Structure For Coiled Tubing Operation

Coiled tubing bidirection drilling jar is a common-used stuck freeing tool in coiled tubing operation.The overall size of it,which is restricted by coiled tubing operating environment,is smaller than normal jars,so that the structural rationality of its key part influences the service life of the jar a lot.Failures like fatigue fracture of the impact tube,excessive abrasion or crushing of the spline teeth in the torque transmitting mechanism,and sealing failure of the damping mechanism which is usually caused by valve wearing in field application,have a serious affect on the tool’s unstuck efficiency.Therefore,in order to provide a method of simulation analysis for enhancing the unstuck efficiency and prolonging its service life,this thesis has studied and optimized the key structure of the Coiled tubing bidirection drilling jar,and the specific content of it is as follows:(1)Analyze the structure of different kinds of jars and the working condition of the coiled tube,and determine the object of this research.Complete the load analysis of the jar under balanced working condition and jarring working condition so as to deduce the calculating formula of the impact force.Analyze failures of the jar and propose solutions for them.(2)Simulate the key part of the torque transmitting mechanism in order to get the affecting laws of its carrying capacity under the influence of different tooth height or tooth width.Obtain the optimal combination of tooth height and tooth width after further combinatorial optimization.Build finite element models of the spline pair with different teeth number so as to gain its influence on the carrying capacity of the mechanism.(3)Establish the finite element simulation model of the impact part of the jar in order to propose an improved program for the geometric transition area between impact tube and spline mandrel,as well as the area between spline mandrel and down joint.Confirm the optimal program by finite element simulation.(4)Determine the best inclination of the matching surface between valve and hydraulic cylinder by the DOE and interval linear optimization of the damping mechanism,which are in the fundamental of the auto simulation process combined with ISIGHT and ABAQUS.Obtain the optimal range of the interference fit between the value and impact tube through a process of calculation,simulated analysis,error analysis,approximate model,and simulation verification.