Study On The Law Of Axial Force And Torque Transmitting Under Surface Rocking Drill String Motion

Nowadays directional drilling technology has become a very important means in oil and gas exploitation,the slide drilling composed of steering motor and MWD(measurement while drilling)system is one dominant directional drilling technology due to the economic and technical factors that limitted rotary steering drilling technology.Stick-slip vibration will lead to the damage of drilling bits and the condition of motor stall because of the existence of downhole friction during the slide drilling.Based on the above problems,a new technology called automatic slide drilling control system was studied and developed abroad.Automatic rocking drill string on the ground has been proved to solve the problem of adjust tool-face orientation and back pressure in slide drilling.Based on domestic top drive steering control system design actuality,there is still a certain gap of automated directional drilling system and method with foreign countries.Therefore,studying the law and motion state of axial force and torque transmitting under surface rocking drill string motion is main research direction of this technique.Firstly,the finite element model of the horizontal section of drill string is established,and the numerical simulation is carried out based on this model,the impact of different surface rocking parameters on bit pressure and tool face stabilization are researched.The results of numerical simulation showed that: with the increase of rocking velocities and the amplitude of rotation angle,the value of weight on bit becomes greater and weight transfer becomes smoother.Tool face varies with the fluctuation of weight on bit;tool face generates counter-clockwise rotation once weight on bit suddenly increases.Secondly,on the basis of similarity theory,establish links between the field condition and the laboratory experiment,select the size and material parameters of the drill string and simulation wellbore through the similarity principle.In order to carry on experimental study,I design and develop horizontal well simulation drilling experimental device.This experimental device includes driving system,system of simulation wellbore and drill string,system of data acquisition and experimental system of process control,motion state of under surface rocking drill string motion during slide drilling could be simulated reconstruction through this experimental device.Finally,the influence of weight on bit and tool face stabilization of surface rocking parameters(different amplitude of rotation angle,different rocking velocity)are studied through laboratory experiments.The experimental results show that weight on bit becomes bigger when rocking velocity and the amplitude of rotation angle increasing,it is easiser to obtain desired weight on bit,keep smoother weight transfer and eliminating stick slip,tool face is becoming more stable.By contrasting the experimental results and the numerical simulation results,which shows they are in good agreement.In this paper,I systematically study on the law of axial force and torque transmitting under surface rocking drill string motion through numerical simulation and experiments,it provides the corresponding theoretical basis for the field application of the top drive steering control system for slide drilling.