Mechanics Research On Combination Of Drilling Tools In Dislocation Wells

With the production time of the oil wells constantly expanding, and influenced by the production and development programs, different geological, engineering, ect, the technical condition of the casing in oil well is gradually deteriorated and the casing is deformed or even damaged. It needs repairing the casing damage wells to resume production.For the casing damage form of dislocation and diameter reducing under compressing in two well-repaired process, the formula of WOB, torque and other loads about milling shoe and cone mill bit is deduced by simplifying the cutting mode between drill bit and damage casing; Considering the structure of combination drilling units, the contact and collision state between the drilling and casing, a variety of external loads and other factors, a nonlinear transient dynamic analysis model of milling shoe and cone mill bit is established that reasonably describes the drilling state in the underground. With dynamic gap element theory, the collision and contact problem between drilling tools and the casing is solved; With spatial beam element Kinetic analysis equation and NEWMARK method, dynamics analysis of well repaired problems can be done. The research provides a effective method for doing drilling transient dynamic analysis. Based on the model and the theory, dynamics analysis software is compiled to do dynamics analysis for the two types of combination drilling tools:milling shoe and cone mill bit. The state of the force and deformation of the combination drilling tools and the collision and contact with casing wall and the motion state of combination drilling tools are all got and indoor experiments and kinetic analysis are all done. The research result provides a theoretical basis for the selection of process parameters and the design of drilling tools combination.