Study On The Dynamics Of Working Mechanism Of Deep-Hole Dual-Pipe Directional Drilling Rig

Nowadays,directional drilling technology combined with screw drill and PDC bit has become one of the main process technologies in drilling engineering.However,in the actual drilling,drill string caused by drilling vibration,drill failure and buried drill,stuck drill and other underground accidents,at the same time in the feeding and pulling the feed mechanism there is fatigue strength.Therefore,In this paper,the working mechanism of deep hole double pipe directional drilling rig is studied,and the working mechanism of the directional drilling rig is analyzed by the finite element theory,combined with the actual conditions of the cobalt well and the characteristics of the directional drilling technology.The study provides a theoretical basis for improving the service life of drilling system and dynamic optimization of well trajectory precision,which provides theoretical basis and technical support for the optimization design of horizontal directional drilling feed mechanism and the further research and application of horizontal directional drilling technology.By analyzing the working principle of the boring machine of the double pipe directional drilling rig,based on the theory of structural element method,the drilling tool structure is simplified,the vibration model of drilling tool is established in three directions:axial,transverse and twist.In view of the drilling tool failure caused by resonance,based on the nonlinear vibration theory,by means of AN SYS parametric modeling,the finite element model of the drilling tool is established,the modal analysis and the harmonic response analysis are carried out.The natural frequencies and the vibration modes of longitudinal vibration,lateral vibration and torsional vibration of the drill are calculated and analyzed respectively.and the effects of drilling length and drilling fluid density were considered.at the same time,the resonant characteristics of the drilling tool under different excitation frequencies and the speed of resonance are analyzed.According to the fatigue strength and stress concentration problem of feed mechanism,through the static finite element theory,the static finite element model of feed mechanism is established,the static mechanical calculation of feeding mechanism under feeding and pulling conditions is carried out,and the distribution law of equivalent stress and total deformation displacement under different working conditions is obtained.It is verified that the strength requirement is satisfied under the static strength,and the location of fatigue damage was determined.Aiming at the problem of vibration failure of drilling tools in dynamic drilling and underground accidents such as burial drill,according to the explicit dynamics theory combined with the penetration contact,a nonlinear finite element model of multi-body solid-liquid coupling for drilling system with full directional well in horizontal directional drilling is established,using LS-DYNA display differential algorithm,the finite element models of the soft rock and the hard rock are obtained respectively.The rock breaking condition,the axial trajectory of the drilling tool and the drilling tool movement are analyzed;Nonlinear vibration characteristics of drilling tool system;rock breaking force and rock breaking torque of PDC bit on rock.Finally,in order to verify the rationality of the model,the finite element calculation results and the experimental data were compared.The study provides a theoretical basis for the improvement of drilling tool life,well trajectory prediction-control and reasonable vibration reduction.