Structure Design And Simulation Of Downhole Supercharger

In view of the slow speed of oil and gas well drilling under complex geological conditions,fully utilizing hydraulic energy combined with mechanical action to break rock can effectively improve drilling speed.Drilling fluid is directly ejected through jet nozzle of drilling bit at the bottom of the well after the pressure is increased,thus the effect of hydraulic rock breaking is achieved.At present,the development of the downhole supercharger still belongs to the exploration stage,and the more mature products have not been applied to the drilling site.Based on this,a new type of downhole supercharger is designed on the basis of previous research and the requirement of field operation.This article mainly from the downhole supercharger structure design,power conversion mechanism,high-pressure nozzle erosion and downhole flow field numerical simulation four aspects were studied in detail.The research content of this article is summarized,including the following aspects:Combined with the actual working conditions of the downhole supercharger,a design scheme of the supercharger is put forward.The structural design of the key parts,such as the power conversion mechanism,the supercharging mechanism,the power input shaft and so on,is completed.Speed,torque and working continuity of power conversion mechanism are calculated.Multi-body dynamic model of power conversion mechanism is established by using ADAMS software,and the law of motion is analyzed.Explicit dynamics model of power conversion mechanism is established by using ABAQUS software,and the explicit dynamic analysis is done.The erosion wear model of high pressure nozzle is established.The erosion wear of nozzle under different shapes is calculated by FLUENT software,and the influence rule of particle diameter,particle volume fraction,dynamic viscosity of drilling fluid and the flow rate of drilling fluid on the erosion rate of nozzle is studied.The supercharger drilling bits 3D flow field was analyzed by numerical simulation using fluid simulation software FLUENT.Change rule of different nozzle angles and different nozzle distance on flow field at the bottom of a well is studied.According to the research content of this paper,the main conclusions are as follows.The design scheme of the downhole supercharger is determined,and the design of the whole structure and the calculation of the working parameters are completed.In one period,the driven cylindrical cam has a larger contact force and fluctuates in the range of 1.25×10~5~4×10~5N during the downward process,and the contact force is small and fluctuates in the 0~5×10~4N range during the reset process.In one period,the torque of the drive cylindrical cam is the largest in the initial position.With the rotation of the drive cylindrical cam,the torque begins to fluctuate up and down and has a general decreasing trend.When the cam turns,when the movement position reaches the peak of the two cam,the torque is basically 0 and begins to run with approximate empty load.In a period,the speed of the vertical direction of the driven cylindrical cam at the beginning position is the largest in the positive direction of the Y axis,and the maximum value is about 1000 mm/sec.With the rotation of the cam,the velocity begins to fluctuate up and down and presents a general decreasing trend.When wave peaks of the two cam contact,the velocity drops to 0,and the drive cylindrical cam begins to run with approximate empty load.And then the driven cylindrical cam is under the effect of spring force.In the negative direction of the Y axis,the velocity increases gradually and reaches the maximum value of about-400mm/sec.When the cam wave peak is in contact with the trough of wave,the velocity changes from the maximum negative direction to the maximum positive direction.When the time t is in 0.002~0.5s,the maximum equivalent stress of the drive cylindrical cam and the driven cylindrical cam occurs in the place where they are in contact and it meets strength requirements.The maximum equivalent stress rises first and then drops and then rises.Under the shape of different nozzle,the maximum erosion rate increase in order of streamlined,conical,cylindrical,straight cone type.And the maximum erosion rate and average erosion rate of the nozzle gradually decrease with the increase of the particle diameter and the dynamic viscosity of the drilling liquid,and the maximum erosion rate and the average erosion rate of the nozzle gradually increase with the increase of the number of particles and the flow of drilling liquid.With the nozzle side angle and jet distance decreasing,crossflow velocity at the bottom plane of the well increases.