Self-locking pressure-controlled mechanism of jet crushing tool for hydrate exploitation
The jet crushing tool is key for crushing and cavity formation of hydrate reservoirs in gas hydrate exploitation.The study aims to solve the problems of similar tools,such as uncontrollable nozzle switching state,and non-automatic switching between borehole drilling and jet crushing expansion.Firstly,a jet-crushing tool with a self-locking pressure-controlled sliding core was designed,which can change the position of the sliding core by controlling the flow rate of drilling fluid at the sliding core inlet,and realize the opening and closing of the nozzle and the self-locking and unlocking of the sliding core.Secondly,numerical simulation methods were employed to study the effects of structural dimensions on the pressure drop and axial force inside the sliding core,and the optimal structural parameters inside the sliding core were obtained.Finally,an experimental prototype was machined to verify the tool's performance.The results show that when the inlet diameter of the sliding core is 45 mm,the inlet angle is 30°,the diameter of the outlet and the straight pipe section is 30 mm,and the inlet flow rate is 470 L/min,the effect is the best.The jet nozzle will not be opened at the conventional borehole drilling flow rate.When the inlet flow rate is 453 L/min,the nozzle is fully opened and the sliding core is self-locked.When the inlet flow rate is 253 L/min,the sliding core is unlocked and the nozzle is closed gradually.The maximum relative error between the tool's self-locking flow rate and the design flow rate(470 L/min)is 3.62%,which is within an agreeable error range.Therefore,under the designed drilling fluid flow rate,the jet nozzle of the self-locking pressure-controlled sliding core jet crushing tool can be opened and closed normally,and the sliding core can complete self-locking and unlocking.
natural gas hydratejet crushing toolself-lockingnumerical simulation
国家科技期刊平台
NSTL
万方数据
