Research On Cementing Sleeve Of Shale Gas Well Driven By Micro Hydraulic System

Shale gas,as a kind of unconventional natural gas resources,has become China’s strategic energy.In order to improve the exploitation level of shale gas,it has been proposed to build intelligent and digital oil and gas fields in the world to realize the increase of oil and gas resources.In the process of intelligentization and digitalization of oil and gas fields,the multistage fracturing technology of cementing slip sleeve as an efficient stimulation technology has attracted the attention of large energy service companies at home and abroad.At present,the multistage fracturing technology of cementing sliding sleeve can be divided into mechanical switch sliding sleeve and hydraulic switch sliding sleeve in the opening mode of sliding sleeve.In contrast,hydraulic switch sliding sleeve with hydraulic system large thrust,convenient control,flexible layout of the advantages of more and more attention by the industry.However,due to the harsh environment of high temperature and high external pressure in shale gas Wells and the technical requirements of narrow space,the current hydraulic switch sliding sleeve only provides the liquid pressure on the ground,and drives the switch of sliding sleeve by conducting the pressure to the stratum actuator through the gas collecting tube bundle.No significant progress has been made in the research and design of other drivers.To sum up,there are two main technical challenges.One is the lack of a completely independent micro-hydraulic drive system for the hydraulic switch sliding sleeve in the downhole.Second,how to integrate the independent microhydraulic drive system and the cementing slip sleeve conformally is also a difficulty,that is,how to reasonably arrange the hydraulic components on the cementing slip sleeve can ensure the reliability and stability of the cementing slip sleeve and make the whole system adapt to the downhole environment.In view of the challenges and difficulties in the above mentioned hydraulic switch type cementing slip sleeve,this paper studies and designs a kind of micro-plunger pump suitable for the narrow space environment underground,and puts forward the method of using micro-plunger pump to drive cementing slip sleeve to realize the controllable opening and closing of cementing slip sleeve.The compact design of micro-plunger pump is carried out,and the key technologies such as friction pair,volumetric efficiency and self-priming performance are studied.A test system suitable for micro-plunger pump is set up.The problems of low volume efficiency and poor self-suction performance of micro-plunger pump are analyzed.The mechanical structure of cementing slip sleeve is designed and its strength is checked,and the whole micro-hydraulic drive system is put forward to be installed in the u-shaped groove of the outer cylinder liner of cementing slip sleeve,and the inner slip sleeve is used as the actuator of the micro-hydraulic drive system.The conformal integration of micro-hydraulic drive system and cementing sleeve is realized.It lays a foundation for effective fracturing of cementing sleeve in shale gas well.