Research and design of hydraulic system for peristaltic crawler in oil downhole
                          GAO Feng1, WU Qing2, ZHAN Baoping2, YANG Ruikai1,WANG Huiwu1, WANG Yan1
(1.School of Mechanical and Precision Instrumental Engineering, Xian University of Technology, Xian  710048, China; 2.Xian WeiSheng Electronics Technology Co., Ltd., Xian 710304, China)


Abstract: Aiming at solving the problem that the drilling tools and logging instrument can’t be put to the drilling sections only by gravity during drilling operation in horizontal well and highlydeviated well, a coiled tubing peristaltic crawler with high dragging ability was proposed，which used working fluid as hydraulic transmitting medium to provide power for drilling and putting down instrument. According to the working principles of crawler，a hydraulic circuit intended to realize creep walking of the crawler was designed with whole determined technical parameters of valves. After modeling hydraulic system and setting of systematic parameters properly，the dynamic performance of hydraulic circuit was simulated and analyzed with the software AMESIM, by which the changing laws of internal force for safety valve, switching valves between fore and rear claws as well as fore and rear progressing cylinders were obtained. The results show that the presented hydraulic system can meet the reliability requirements on peristaltic motion, and performance parameters of all control valves can ensure the enough dragging fore, which would lay the theoretical foundation for developing prototype.
Key words: peristaltic crawler; hydraulic system design; driving force; performance analysis; oil wells