Axial and torsional impact drilling technology is used to improve the drilling efficiency of hard rock formation in the deep underground.Still,the corresponding theory is not mature,and there are few correlative resea...Axial and torsional impact drilling technology is used to improve the drilling efficiency of hard rock formation in the deep underground.Still,the corresponding theory is not mature,and there are few correlative research reports on the rock-breaking mechanism of axial and torsional coupled impact drilling tools.Considering the influence of the impact hammer geometry and movement on the dynamic load parameters(i.e.,wavelength,amplitude,frequency,and phase difference),a numerical model that includes a hard formation and single polycrystalline diamond compact cutter was established.The Riedel-Hiermaier-Thoma model,which considers the dynamic damage and strength behavior of rocks,was adopted to analyze the rock damage under axial and torsional impact loads.The numerical simu-lation results were verified by the experimental results.It was found that compared with conventional drilling,the penetration depths of axial,torsional,and axial-torsional coupled impact drilling increased by 31.3%,5.6%,and 34.7%,respectively.Increasing the wavelength and amplitude of the axial impact stress wave improved the penetration depth.When the bit rotation speed remained unchanged,increasing the frequency in the axial and circumferential directions had little effect on the penetration depth.However,as the frequency increased,the cutting surface became increasingly smooth,which reduced the occurrence of bit vibration.When the phase difference between the axial and circumfer-ential stress waves was 25%,the penetration depth significantly increased.In addition,the bit vibration problem can be effectively reduced.Finally,the adjustment of engineering and tool structure parameters is proposed to optimize the efficiency of the axial-torsional coupled impact drilling tool.展开更多
During the drilling process,cuttings carrying in the horizontal well section is relatively difficult,and cuttings beds form easily.A new type of hydraulic-magnetic coupling transmission cuttings cleaning tool is propo...During the drilling process,cuttings carrying in the horizontal well section is relatively difficult,and cuttings beds form easily.A new type of hydraulic-magnetic coupling transmission cuttings cleaning tool is proposed,but the magnetic torque transmission influence mechanism,the optimal magnetic circuit structure and the magnet configuration are still yet to be studied.To this end,the finite element numerical simulation method is applied to analyze the influence of magnetic circuit structure and permanent magnet geometry on magnetic torque.The results of numerical simulation and laboratory experiments show that(1)the magnetic torque transmission efficiency can be improved by increasing the air gap flux density,reducing the magnetic reluctance and increasing the magnetostatic energy accumulation;(2)the magnetic torque increases first and then decreases as the number of pole-pair increases.The magnetic torque of 12 pairs of pole pairs reaches the maximum value;(3)by the coupling of the amount of magnets under the constraints of the effective section magnet coverage area percentage and the thickness of the magnet,it is obtained that when the thickness of the permanent magnet is 8.4 mm and the magnet coverage area percentage on the effective section of the tool is 71%,the maximum magnetic torque is generated per unit volume of magnet;(4)the absolute error of the indoor experimental result and the numerical simulation result is less than 17%,which can meet the engineering calculation accuracy requirements.It is concluded that the established numerical simulation model is reasonable and can be used as a technical means for the optimization analysis of the tool structure.展开更多
基金supported by the National Natural Science Foundation of China(52004013,U1762211).
文摘Axial and torsional impact drilling technology is used to improve the drilling efficiency of hard rock formation in the deep underground.Still,the corresponding theory is not mature,and there are few correlative research reports on the rock-breaking mechanism of axial and torsional coupled impact drilling tools.Considering the influence of the impact hammer geometry and movement on the dynamic load parameters(i.e.,wavelength,amplitude,frequency,and phase difference),a numerical model that includes a hard formation and single polycrystalline diamond compact cutter was established.The Riedel-Hiermaier-Thoma model,which considers the dynamic damage and strength behavior of rocks,was adopted to analyze the rock damage under axial and torsional impact loads.The numerical simu-lation results were verified by the experimental results.It was found that compared with conventional drilling,the penetration depths of axial,torsional,and axial-torsional coupled impact drilling increased by 31.3%,5.6%,and 34.7%,respectively.Increasing the wavelength and amplitude of the axial impact stress wave improved the penetration depth.When the bit rotation speed remained unchanged,increasing the frequency in the axial and circumferential directions had little effect on the penetration depth.However,as the frequency increased,the cutting surface became increasingly smooth,which reduced the occurrence of bit vibration.When the phase difference between the axial and circumfer-ential stress waves was 25%,the penetration depth significantly increased.In addition,the bit vibration problem can be effectively reduced.Finally,the adjustment of engineering and tool structure parameters is proposed to optimize the efficiency of the axial-torsional coupled impact drilling tool.
基金supported by the National Major Science and Technology Project,“Drilling Hydraulics and Hole Cleaning Technologies for Structurally Complex Cluster Wells”(No.2017ZX05009-003)the National Natural Science Foundation of China“Study on the Rotary Transmission Mechanisms of Hydraulic-Magnetic Coupling Self-Rotating Hole Cleaning Tool”(No.51674087).
文摘During the drilling process,cuttings carrying in the horizontal well section is relatively difficult,and cuttings beds form easily.A new type of hydraulic-magnetic coupling transmission cuttings cleaning tool is proposed,but the magnetic torque transmission influence mechanism,the optimal magnetic circuit structure and the magnet configuration are still yet to be studied.To this end,the finite element numerical simulation method is applied to analyze the influence of magnetic circuit structure and permanent magnet geometry on magnetic torque.The results of numerical simulation and laboratory experiments show that(1)the magnetic torque transmission efficiency can be improved by increasing the air gap flux density,reducing the magnetic reluctance and increasing the magnetostatic energy accumulation;(2)the magnetic torque increases first and then decreases as the number of pole-pair increases.The magnetic torque of 12 pairs of pole pairs reaches the maximum value;(3)by the coupling of the amount of magnets under the constraints of the effective section magnet coverage area percentage and the thickness of the magnet,it is obtained that when the thickness of the permanent magnet is 8.4 mm and the magnet coverage area percentage on the effective section of the tool is 71%,the maximum magnetic torque is generated per unit volume of magnet;(4)the absolute error of the indoor experimental result and the numerical simulation result is less than 17%,which can meet the engineering calculation accuracy requirements.It is concluded that the established numerical simulation model is reasonable and can be used as a technical means for the optimization analysis of the tool structure.
