Design And Research On The Hydraulic System Of Shale Gas Rotary Sidewall Coring Robot

Oil and gas resources are the blood of industry.At present,they play an important role in the development of a country.The research on horizontal wells and shale gas production technology is imminent.How to use the sidewall coring device of shale gas horizontal well to bring rock samples back to the surface for lithology,electricity and oil-bearing analysis is the primary problem.The rotary sidewall coring device that has been studied at home and abroad does not take into account the complex quality conditions of Sichuan and Chongqing area,which has suffered severe late transformation.It can not adapt to the formation of many regions in China,and has high maintenance cost,low coring efficiency and low reliability.Therefore,it is not suitable for shale gas exploration and development in this area.In order to solve the problem of coring difficulty in long horizontal section of shale gas in Sichuan and Chongqing area,Xihua University for the first time combined downhole crawler with Rotary Sidewall Coring machine,designed a kind of Rotary Sidewall Coring machine with comprehensive functions of downhole crawling,centralization,pushing,coring,sample storage and unfreezing,which can complete downhole long horizontal section coring operation.Therefore,this paper studies the hydraulic control system of shale gas rotary sidewall coring robot.(1)This paper makes a comparative analysis of the current research on the hydraulic system of the rotary sidewall coring robot,which also provides a certain reference value for the design of the hydraulic system principle of the shale gas rotary sidewall coring robot with small volume,integration and precise control as the breakthrough point.(2)Combined with the coring action that the coring robot needs to complete when working underground,according to the characteristics of long horizontal section coring,the linear slideway structure is selected.After the reasonable selection of hydraulic components,the hydraulic system of Rotary Sidewall Coring robot coring sub is designed in detail.In view of the possible sticking phenomenon,the hydraulic system is improved.The simulation results of AMESim show that the design of the hydraulic system is reasonable and feasible.(3)In order to save space and simplify the structure,the hydraulic system of the crawling sub and the hydraulic system of the centralizing sub are designed in the same circuit with the same power input source.The AMESim simulation of the hydraulic system is carried out,and the simulation results are analyzed to achieve the purpose of smooth crawling,which proves the rationality of the design.(4)A new type of C-shaped slip ring combined seal structure is proposed for drilling and core pushing.The change of external medium pressure is taken as a variable,and the finite element analysis of this new type of combined seal structure is carried out by ANSYS.The results show that the contact stress at the slip ring and the adaptive stress of the seal structure increase with the increase of medium pressure,and the contact stress is less than the allowable stress of the material It can ensure good sealing effect.Through the simulation analysis of the designed hydraulic system and sealing structure,it can be seen that the hydraulic system can better complete the coring and crawling action of coring sub and crawling sub in the underground,and the sealing structure can also play a better sealing role,which has a certain engineering practical application value.