Structure Design And Dynamic Analysis Of Slide Valve Hydraulic Oscillator

With the development of society and the progress of science and technology,people's demand for oil and gas energy is increasing.With the continuous development of oil and gas resources,shallow onshore oil and gas resources are gradually depleted.The focus of oil and gas exploration and development has gradually shifted to thin onshore oil and gas reservoirs,deep onshore oil and gas reservoirs,offshore deep-sea oil and gas reservoirs and shale oil and gas reservoirs.Oil drilling is developing towards deep wells,horizontal wells and extended reach wells.When drilling,the drill pipe string will inevitably contact with the well-bore,resulting in greater friction resistance and "pressure support" phenomenon,which will significantly reduce the WOB transferred to the bit and cause bit idling in serious cases.In the existing down-hole vibration drag reduction tools,hydraulic oscillator is widely used to overcome the pressure support.At present,the pulse unit of the hydraulic oscillator mainly adopts the disc valve structure.The static valve seat of the disc valve contacts with the end face of the moving valve disc.Affected by the end face contact pressure and the rotation of the moving valve disc,the wear of the valve disc is very serious,which greatly reduces the working life of the hydraulic oscillator.In this paper,the development history and research status of hydraulic oscillator at home and abroad are investigated,and the structure and principle of various friction and drag reduction tools are understood.On this basis,combined with the actual working conditions,a new type of slide valve hydraulic oscillator is designed.The slide valve hydraulic oscillator designed in this paper is divided into three parts,which are the oscillation short,the power short section and the pulse unit.The pulse unit is a slide valve type structure,which avoids the wear phenomenon caused by the end contact of the original hydraulic oscillator pulse unit.Since the pressure pulse generated by the pulse unit needs to be fed back to the oscillation nipple to cause oscillation,it is necessary to ensure that the pulse pressure waveform can have a certain duration when the maximum pressure drop and the minimum pressure drop occur.According to this requirement,based on the fluid continuity equation,Bernoulli equation,water pad resistance and head loss,the valve group is analyzed theoretically.The working condition of the valve group is simulated by CFD dynamic grid technology.The structure of the existing valve group is improved.Within the range of pressure drop,the valve port shape,the inclination angle of the port and the valve port are improved The length is optimized and the moving law and stroke of the valve are determined.The structure of the valve port obtained is that there are 5 holes with a diameter of 10 mm at the bottom,the side wall flow channel is round groove,the inclination angle of the flow channel is 15 ° and the length of the valve port is 40 mm.The motion law of the moving valve is a sine function,and the stroke is 60 mm,the pressure drop range is 0.172 ?4.81 mpa.Because the hydraulic oscillator designed in this paper avoids the wear phenomenon caused by the end contact,the main wear phenomenon is shown by erosion.Compared with the existing vertical valve hydraulic oscillator,the maximum erosion rate of the two hydraulic oscillators is simulated by fluent DPM model.The maximum erosion rate of the spool valve group structure designed in this paper is reduced by about 23%.According to the motion law and stroke of the moving valve,the power conversion mechanism is designed.The power conversion mechanism converts the rotary motion of the transmission shaft into the reciprocating motion of the moving valve.The most important parts of the power conversion mechanism are the track,the transmission pin and the transmission shaft.The transmission pin is placed in the track and connected with the moving valve.The track rotates with the transmission shaft and drives the moving valve to move back and forth.The orbit is divided into upper and lower parts with special closed surface.The relationship between the speed and acceleration of the pin and the rotation angle of the track is deduced,and the relationship between the force and torque of the pin and the rotation angle of the track is obtained.The simulation results are consistent with the theoretical derivation,The maximum torque is 115N·m and the maximum positive pressure is 6100 N.According to the relevant parameters of the power conversion mechanism,the power motor part is optimized and designed.The screw motor is selected as the power motor of the hydraulic oscillator in this paper,and the connecting shaft is designed to extract the revolution speed of the screw motor,so as to meet the working requirements.Based on the pressure pulse of the oscillating short spring group,the axial force is calculated.According to the proposed amplitude,the disc spring group is calculated theoretically and is calculated by ANSYS The simulation results show that the load displacement curve will form a hysteresis area according to the combination scheme of each group of disc springs during the loading unloading process.The analysis shows that the hysteresis area reflects the energy consumption in the work of the disc spring group.The disc spring group which meets the design requirements and consumes less energy is selected as the disc spring combination with short oscillation section,In this paper,the combination scheme of disc spring group is a series of 8 disc spring pairs.According to the stress of the key parts,the strength of the key parts is checked by theoretical calculation and finite element simulation.The results show that the material of the slide valve hydraulic oscillator meets the strength requirements.