Design Of Telescopic Downhole Hydraulic Tractor

With the continuous exploration of petroleum resources,the technology of oil horizontal wells is becoming much more mature.It also makes the problems of horizontal wells logging and equipment delivery obvious nowadays.Petroleum industry solve these with three main methods:one is drill rod delivery,second is pump rigid tappet delivery,third is coiled tubing(CT)delivery.However,these always meet some limited situation,it's easy to damage the well wall and cause jam;long construction period and cost too much;limited adaptation of horizontal wells and can't meet all the conditions.Thus,people urgently need a vehicle which is available for pulling device in the horizontal wells.Since the late 1990s,there have been a number of foreign companies have developed the new technology for horizontal wells-downhole tractor.The normal downhole tractors can be devided into two sorts:wheel-drive tractors and inchworm tractors.This paper is based on the research for world-wide downhole tractors and with the support of Sichuan Science and Technology Project,and aimed at shorten the gap with advanced strong-traction foreign tractors.The goal is to develop a hydraulic drive inch-worm down hole tractor which accomplishes at least 1 ton traction force.Its diameter should be under 100mm,can bear the harsh temperature and pressure up to 100? and 40MPa,the tractor also should work at the speed over 100m/h.The action part of the tractor is the base of this research.This paper started at the mechanical structure and the hydraulic drive methods of the action part.The research team then introduced and designed the self-lock grippers of the tractor.After that the research team did the drawings and produced the prototype of action part of tractor.The research finally has accomplished the following results:1.Mechanical structure designed by Solid Edge ST8 CAD software;2.The paper used AMESim to build the hydraulic model of the tractor system,did the work condition simulation and got the theoretical cycle time,the traction force and support force.3.Modeled the virtual prototype in ADAMS,and made several dynamics simulation s based on the results of AMESim.The experiments in ADAMS proved the movement and the self-lock gripper designs.4.Checked the internal and external anti-pressure performance.Compared the feasibilities among the on-ground and in-well hydraulic sources.A static simulation of gripper and well wall was also done by FEMAP finite element software.5.Produced a prototype of the action tractor and the hydraulic control system.Have made a movement proven experiment,and designed the traction force experiment.The final experiment has proved the movement theory of design.It meets the requirements of our project.The rebound movement of support cylinder are also a serious problem,which is reflected at the same time.At the last of the paper,we introduced a improve proposals for it.