井下钻柱减振增压装置工作特性的仿真研究

Simulation Research of Working Characteristics of Downhole Drill String Absorption & Hydraulic Supercharging Device

井下钻柱减振增压装置是一种用于实现井底超高压射流辅助破岩的钻井工具,该装置的工作原理是利用井底钻柱振动能量,采用活塞激励的方式调制超高压射流。为研究各参数对该工具工作特性的影响规律,为其现场应用提供理论依据。基于该工具的工作原理,建立了数学模型并进行了仿真分析,对其工作特性进行了研究,以有效破岩水功率(单位时间内装置输出钻井液携带的有效破岩能量值)为优化指标,得出了钻进参数及超高压喷嘴当量直径对其工作特性的影响规律:装置输出压力的峰值随着超高压喷嘴直径的增大逐渐降低;随着钻压、转盘转速的增大而升高;当喷嘴直径为3 mm时,装置输出的有效破岩水功率最大;有效破岩水功率随着钻压、转速的增大而增大。为使单位时间内装置输出的有效破岩水力能量最高,钻进参数与超高压喷嘴直径之间存在最优参数配合。

The Downhole Drill string Absorption & Hydraulic Supercharging Device is a downhole tool for rock breaking,which is implement by using assiated ultra-high pressure jet.Based on the working principle of the device of using vibration energy of the downhole drill string,the method of piston excitation is used to modulate ultra-high pressure jet to improve the rate of penetration( ROP) in drilling well.In order to research the influence law of each parameter on working characteristics of the tool,theoretic basis was provided for its application on site.Based on the woring principle of the tool,mathematical model was established with simmulated analysis,and its working characteristics were researched.By taking the Effective rock water power( The power contained in drilling fluid which could break rock output by the device) as the optimization goal,the influence law was obtained between both the drilling parameters of tool and the ultrahigh pressure nozzle equivalent diameter with performance characteristic.The results show that along with increasing of the ultrahigh pressure nozzle equivalent diameter,the peak pressure output by the device is decreased,and increased along with increasing of both weight on bit and elastic stiffness.When the diameter of jet nozzle is at 3 mm,the effective rock breaking output of the device of water power is at maximum.Along with increasing of drilling pressure and rotational speed,the effective rock braking water power is increased.In order to achieve the best working effect of the device for rock breaking water power in unit time,there is an optimal combination of the parameters which between the drilling parameters and the ultrahigh pressure nozzle equivalent diameter.