Design, Mechanics Research And Experimental Analysis Of New Type Rotary Screw Drilling Tools

With the rapid development of the world economy,the demand for oil and gas resources is increasing,while the shallow oil and gas resources of good storage are increasingly depleted,and the exploration and exploitation of oil and gas is bound to develop in more complex strata.When the well depth is increasing,the hardness and strength of the rock are obviously increased under the confining pressure of the formation,which leads to a series of problems such as low rock-breaking efficiency,low life of bit and drastic decrease of ROP(rate of penetration).In order to solve this problem,a new type of rotary-percussive drilling tool based on the PDM(positive displacement motor),or rotary-percussive PDM,is proposed in this paper,the following research on the rotary-percussive PDM has been carried out using oil and gas wells engineering,mechanical design and theory,vibration,dynamics,experimental testing and signal processing and other related theories and methods.The structural design and working principle of the rotary-percussive PDM are introduced in detail.According to the structural characteristics of the tool,the basic calculation of the powertrain is studied,and the structural design and mechanical analysis of the three systems are carried out respectively.By designing the different motion curves of the cam mechanism of the impact system,the angle,force and torque are compared and analyzed to select the optimal motion curve;by using the impact rocking theory,the impact theoretical model is established,the impact of the impact system is calculated and analyzed;the thrust bearing design of the bearing system,and the basic computing and analysis of the rubber shock absorber are carried out;the related researches of the oil seal system design and working principle are carried out.By analyzing the mechanical relationship of the working process of the key components of the rotary-percussive PDM and combining with the design parameters of the drilling tool,the working condition parameters and the related mechanics calculation method,the dynamic analysis model of the rotary-percussive PDM in the horizontal well is established,and the vibration displacement,vibration velocity at different nodes and the system vibration spectrum are carried out.In addition,considering the tool "parabolic effect" and "drill string rebound" and other factors,the kinematics and mechanics results of the key structures of the drilling tool are analyzed,including the displacement trajectories of the roller at different speeds and WOB(weights on bit);the mechanical results of the cam-roller,upper and lower bearings,and impact pad at the different WOB.Based on the ADAMS simulation software,the dynamic analysis of the tool impact system is carried out.The simulation output results and theoretical calculation results of the contact force between the roller and the cam,the impact force between the upper shaft and the impact pad,and the upper shaft displacement are compared at the different WOB,so as to verify the latter's rationality and accuracy.According to the experimental study of the indoor bench,the tool test results and theoretical calculation results of the vibration frequency and impact are compared and analyzed.The field test of the tool is carried out,according to the field test data and tool use effect,the results show that the rotary-percussive PDM can effectively improve the ROP.In summary,according to the structure and principle of the rotary-percussive PDM,the structural design and mechanical analysis of the three systems are carried out;the axial vibration model of the tool is established;the ADAMS simulation software 'and the indoor experiment are used to verify the relevant theoretical calculation and model,and finally through the field test,which verifies the site practicality of the tool.The study results have some reference value for the future improvement of drilling efficiency,drill bit rock-breaking technology and tool research.