Research On The Performance Of The Hydraulic System Of The Underground In-situ Measuring Device

The new type of sidewall coring tool with in-situ measurement function solves the problem that conventional coring tools cannot be measured downhole in real time,resulting in inaccurate core parameter measurement.It can achieve the tasks of downhole coring and in-situ measurement.The hydraulic system is a key link in the realization of its mission.Therefore,the hydraulic control system of the sidewall coring tool was designed.The coring device is composed of a pushing mechanism,a coring mechanism,a switching mechanism and a in-situ measuring mechanism.The hydraulic control system of the coring device is composed of a coring module,a switching module,a pushing module,and an in-situ measurement module.A new type of switching lift control system has been designed by adding a safety valve,a two-way throttle valve,and a superimposed relief valve to stabilize the inlet pressure of the switching hydraulic cylinder and avoid oscillation.A new type of drilling control valve was designed,and its static and dynamic characteristics of the drilling control valve were analyzed.Finally,a simulation model of the hydraulic system is established based on AMESim software,and the impact of the two-way throttle valve on the switching hydraulic cylinder inlet pressure,flow rate,piston rod operating speed and switching hydraulic cylinder clearance leakage under different orifice diameters is analyzed.Simulation results show that(1)The spool displacement of the drilling control valve only changes with the change of the input pressure signal of the large pump,which can solve the problem that the large pump pressure and the small pump pressure were affected by the well temperature and depth at the same time,which leads to the system response is lagging and cannot be quickly controlled.(2)When the orifice diameter of the two-way throttle valve is 1.5mm and 3.5 mm,the pressure-flow curve of the switching hydraulic cylinder inlet oscillates greatly within 0～0.15 s,resulting in greater hydraulic shock and greater noise;When the diameter of the two-way throttle valve is 2.5 mm,the inlet flow curve of the switching hydraulic cylinder oscillates less within 0～0.15 s,resulting in less hydraulic shock and less noise.(3)The hydraulic motor speed is stable at 1986 rev/min;the drilling hydraulic cylinder moves 0.056 m in0-10 s and 0.15 mm in 25-50 s.The input pressure of the hydraulic cylinder of the switching circuit is stable at 1.47 MPa,and the flow rate is 9.70 L/min.The inlet pressure of the pushing hydraulic cylinder is stable at 6.5 MPa,the displacement is 0.12 m,the displacement of the pusher hydraulic cylinder is 0.07 m;the displacement of the probe hydraulic cylinder is 0.05 m.There is no pressure fluctuation and the piston rod moves smoothly.The rationality and reliability of the hydraulic system design are verified.