Research On Stick-slip Vibration Characteristics And Torsional Shock Damping Of Drill String System In Highly Deviated Wells

Stick-slip is often considered as one of the greatest sources of damage to polycrystalline diamond compact(PDC)bits and bottom-hole assembly(BHA),and has constantly restricted the development of efficient drilling technology of PDC bits.In addition,the progress of related research has been slow because it is extremely difficult to study the theoretical analysis of highly nonlinear drill-string vibration.Especially in the development of the rapid high angle deviated well drilling process in recent years,there is no literature published about the research results of the stick slip vibration system in the drilling process of highly deviated wells at present due to the complexity of the trajectory of the well.In this paper,random contact and impact between drilling strings and borehole walls at an arbitrary depth and circular direction in a slim-hole well are considered,the process of drilling in real time,and combining the system dynamics and the latest numerical simulation technology,thus a nonlinear dynamic model is established.Based on the nonlinear dynamic model the vibration characteristics of stick slip vibration in the process of drilling high angle well,the influence on stick-slip response of PDC bits while considering different drilling parameters and the influence of torsional impact on stick-slip vibration are studied.The main points of this paper are listed as following.(1)The research status of the stick slip vibration of drill string system is investigated and the research content and research methods are determined.(2)The dynamic model of the drill string system with large angle is established based on the nonlinear coupling vibration and rock interaction by the finite element method.(3)A numerical simulation model is established to study the stick slip vibration characteristics of the drill string system in large angle well and the numerical simulation model is solved by using the display integral algorithm in Abaqus/explicit.The reliability of the numerical simulation results is verified by comparing with the measured data in the field.(4)The characteristics of the stick slip vibration response of the drilling bit and drill string are analyzed based on the analysis of the actual drilling parameters.(5)In order to obtain the influence of drilling system parameters on stick-slip vibration,different groups of the weight on bit(WOB),surface speed(RPM),drillstring length and the friction coefficient of bare wellbore are analyzed.And we also analyzed the influence of different drilling system parameters on other vibrations of BHA.These results further reveal the drill string stick-slip vibration characteristics,explain some phenomenon of drilling construction and provide reference data for the further development of mitigation measures.(6)The characteristics of stick slip vibration response of bottom hole drilling tool under high frequency torsional vibration,the effect of high frequency torsional vibration on the stick slip vibration and the effect of torsional vibration on the system vibration of drill string are analyzed in this paper.This study provides some theoretical support for the development of high frequency torsional impact tool.The vibration characteristics of stick slip vibration in the process of drilling high angle well,the influence on stick-slip response of PDC bits while considering different drilling parameters and the influence of torsional impact on stick-slip vibration are studied in this paper,and this work is helpful to understand the stick slip vibration characteristic of the high angle drill string system and to make the stick slip vibration suppression measure.