Optimal Design Of The Blade-Drived Valve Pulse Generating Device

Enhancement of penetration rate can significantly shorten the drilling cycle and reduce the drilling cost.Hydraulic pulse jet technique can help improve the flow field at wellbore bottom,increase the energy utilization of water power,enhance the cutting-carrying capacity,and contribute to rock-breaking efficiency,which is applicable in soft to intermediate-hardness formations.However,due to the limited space in the wellbore,the design of a long-life,pulse-controllable hydropulse jet generator is difficult,and related research is rare.Thus,this research proposed a blade-drived valve pulse generating device and performed parametrical analysis to its structure parameters.Using Pump Linx Software,effects of the displacement,impeller diameter,number of the blades,helix angle of blade,and torque on the flow field,rotation speed and pressure loss of the power unit were analyzed.On the other hand,using Ansys Software,effects of displacement,rotation speed,number of valve holes,and diameter of valve hole on the velocity distribution,the pressure distribution,and the pulse characteristics of the valve unit were studied.Meanwhile,other numerical simulations were conducted to optimize the design of the blade-drived valve pulse generating device based on effects of rotation speed,pressure loss,and the pulse characteristics.Then,laboratory tests and field tests were carried out to verify the applicability of the blade-drived valve pulse generating device.According to the research findings,the rotation speed of blades can be modified by the number of blades and the helix angle.The pulse characteristics can be adusted by the number of holes.To a ?215.9mm hole,the blade-drived valve pulse generating device should have a helix angle of 60°,an arc-shaped hole,and 2 holes.The laboratory tests indicated an pressure loss of 0.5 MPa,a pressure pulse amplitude of 1.15 MPa,and a pulse frequency of about 10 Hz at a displacement of 23 L/s.Combining with the field data,such a blade-drived valve pulse generating device can help increase the penratration rate by 21.16% at a displacement of 32 L/s.These findings can provide fundamental guidance on the design of pulse generating device,and help advance the understanding about the working mechanisms of the blade-drived valve pulse generating device.