| Cable tractor can be used to deliver precisely the instruments to the desired positon during the process of well logging or workover in horizontal wells.It can not only effectively overcome the difficulty of sending downhole instruments into horizontal wells,but also can significantly save operation time and money.Based on the current research situation and development trend of cable tractor at home and broad,this paper focus on cable tractor and its mechanical structure design,parameters optimization and performance analyzation.1.The structure system of the cable tractor is determined and the corresponding working principle and function is also described.The mechanical structure design of traction sub is completed and two new kinds of centralizer structure are devised.Besides,combined with the structure and working principle of the cable tractor,a computational model of structure parameter optimization and a mechanical model of working under driving forces are established,and the models are solved and analyzed respectively.Based on these models,the relationship between various parameters is presented.2.The parameters of key functional components of the tractor are calculated and optimized and the influence of each parameter on its structure and performance is studied.With a practical example,parameters such as screw-nut stroke?driving wheel gear structure and their variation under different casing pipe types are analyzed.Furthermore,critical performance parameters such as driving force and axial elastic propulsion force,the resistance force during sending down and creeping,going down by the tractor weight,the capability of crossing obstacles and crossing height are also calculated and analyzed.3.A prototype of traction sub of cable tractor for horizontal well is developed and indoor no-load working simulation experiments are carried out.The feasibility of its structure and function principle are preliminarily verifies by the experimental results. |
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