Simulation And Structure Optimization Of New Type Drill String Machine Fluid Coupling Shock Absorber

In drilling operations,the drill string often generates many forms of vibration.Especially when the bit is being drilled,the drill string will eventually cause longitudinal vibration due to uneven bottoms,intermittent pressure on the rock by the teeth of the roller cone,and intermittent breakage of the rock.In vertical well drilling,the longitudinal vibration of the drill string is one of the serious forms of vibration in the drill string vibration.The severe longitudinal vibration not only causes damage to the drilling tool and reduces the rate of mechanical drilling,thereby increasing the cost of drilling.The drill string shock absorber can effectively reduce the amplitude of the longitudinal vibration of the drill string and reduce the load on the drill string during the drilling process.It is of great significance to study the longitudinal vibration of drill string in vertical wells to reduce the harm caused by the longitudinal vibration of drill string during normal drilling operations and to obtain the shock absorption effect by using the drill string shock absorber.In view of the above situations,this paper mainly does the following research:First,the types of existing drill string shock absorbers and the working principle of shock absorbers are studied.The mechanical-hydraulic coupling shock absorber is designed and the scheme is given.The spring characteristic model and the damping characteristic model of the mechanical-hydraulic coupling shock absorber are established and calculated.simulation.Secondly,the working load,environmental load and formation stiffness of the drill string system are studied,and the drill string is discretely established to establish a discrete system model of the drill string longitudinal vibration with a mechanical-hydraulic coupling shock absorber.Analyze its vibration characteristics.Thirdly,based on the elastic rod theory,a mathematical model of drill string longitudinal vibration with a mechanical-hydraulic coupling shock absorber and a simulation model of drill string longitudinal vibration are established to solve the steady state response of the system.By comparing the displacement,load and weight of the drill string in the longitudinal vibration of the drill string under different models,the vibrationanalysis effect of the mechanical-hydraulic coupling shock absorber in the longitudinal vibration of the drill string is verified and analyzed.Finally,on the basis of establishing a mechanical model of the drill string longitudinal vibration with a mechanical-hydraulic coupling shock absorber,the parameters of the mechanical-hydraulic coupling shock absorber are optimized for the system.