Theoretical Analysis And Digital Mockup Design Of Hydraulic Thruster

In the process of drilling the large displacement horizontal well,the drilling pressure generated by the horizontal section of drill string is close to zero,and the drilling pressure is difficult to control;as the contact between bit and the bottom of well is uneven,the vibration of the drill bit is changed,and the vibration amplitude of upper drill is larger.The hydraulic pusher drilling tools can produce a pressure difference,provide energy for the bit,produce the drilling pressure and increase the footage displacement of horizontal section;also,the BHA and the upper drill string form a flexible connection by the hydraulic propulsion type drilling tools,and play a damping effect.This paper mainly focuses on the digital prototype design and theoretical analysis of the hydraulic drilling tool.A spring damper model of drill string system is built by applying the vibration mechanics theory,and the vibration differential equation of the drilling column system is derived.Using MATLAB to compile the corresponding computer program,and solve the problem.Using cascade and multilevel type of the hydraulic pusher drilling tools as a evaluate example of the damping effect,so as to verify the rationality of the model.This paper designed the structures of important part of the hydraulic push type drilling tool(cylinder body,an upper joint,a lower end cover,a piston and a piston rod).Use the three-dimensional model software to design the digital prototype,according to the design size of the structure.Apply ANSYS workbench software to analyze the finite element static and modal of important parts.The results show that all the strength of the important component meets the design requirements.The drill string and the hydraulic push type drilling tool are simplified as a spring damper model.Using the pulse signal,step signal,sine wave,triangular wave signal and Drichlet signal,random signal as the vibration to analyze the dynamic response of drill string system.The upper drill for amplitude of BHA decreased 37%-50%,which shows the damping effect of hydraulic push type drilling tool is better.For the three parameters of the diameter of the piston,the piston rod length and the drilling mud density,establishing the orthogonal test model of "three parameters four level".Optimize the diameter of the piston and length of piston rod of the hydraulic drilling tools.In order to play the advantage of hydraulic propulsion type drilling tool,choosing different key parameters for different density of drilling mud.Finally,simulating internal fluid of the hydraulic push type drilling tool,we can get the cloud gram of pressure and diagram of velocity vector of the mud.Analyze the influence of three main parameters,which are drilling mud density,temperature and clearance,to the drilling pressure.This paper can provide reference for the design and analysis of drilling string vibration damping and the control of drilling tools.