| Horizontal well is one of important methods of unconventional oil and gas resource development.As increasing of length of horizontal section,there is a serious problem that axial force cannot transfer to bit.It reduces drilling efficiency,even lead to fail to drill to design well depth.Therefore,it needs a low-friction and low-cost drag reduction tool.This paper relied on the sub-project of "Sichuan Province Science and Technology Development Plan" sub-topics "Novel Drag Reduction Tool Development" and the sub-project of "The Thirteenth National Science and Technology Major Project" sub-topics"Controllable Compound Steering Drag Reduction System Development and Test".Under basis of existing research on mechanical drag reduction technology,the works of this paper were mainly following aspects:(1)Through extensive existing research and application result on mechanical drag reduction tool,this paper classified these tools and comparison of reduction mechanism of tools.Economic efficiency and security of tools were also compared.On this basis,advantages and disadvantages of drag reduction tools were deeply analyzed.Meanwhile,idea of this paper was proposed.(2)Complicated manufacture and test work of torque clutch tool.Using rotation drag reduction mechanism,this paper proposed design scheme of torque clutch tool.Detail design was conducted.The tool included clutch,hydraulic control system and measurement and control system.The tool adapted parallel clutch unit that can transit high torque in a small space.The power of hydraulic control system adapted differential pressure between wellbore annular and inside pipe.On this basis,key sub-systems were processed,assembled and debugged.(3)Established nonlinear dynamic friction model between drill-string and wellbore.According contact microscopic mechanism and bristle deformation theory,this article established nonlinear dynamic friction model between drilling pipes and wellbore and discrete solution method.Simulation results of this model were good agreement with experimental data.According this model,drag reduction mechanism of drill-pipe rotation,longitudinal vibration and torsional vibration were analyzed.(4)Static evaluation of drag reduction performance of torque clutch was conducted using modified torque&drag model and wellbore circulation pressure model.The best installation sited was also determined.In the modified torque&drag model,there were three situation of torque distribution that no torque was applied on the top of pipes,least torque than friction torque of pipes and greater torque than friction torque of pipes.Calculation method was proposed for three situations.(5)Ability of axial force transition was analyzed in different situation using established dynamic drag&torque model.According force condition of drill pipe,this paper established dynamic drag and torque model by simplifying transverse motion of drill pipes.Numerical solution method was proposed.According established model,varied weight on bit and torque were analyzed in directional drilling process.(6)Clutch and hydraulic control system were tested,engineering prototype test program was proposed.Test results indicated that clutch and hydraulic control system met design requirements.The trial-manufacture was archived intended targets.This article proposed a novel drag reduction tool based systematic investigation and theoretical study.The development work of torque clutch was accomplished.The key sub-systems were tested indoor.The drill-string drag reduction mechanism and effect were analyzed.Reasonable installation position and ability of axial force transition were obtained.The works of this artical was a foundation of next step of tool development.It provides an idea to solve the problem of excessive friction in horizontal well drilling... |
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