水力脉冲空化射流钻井机理与试验

Mechanisms and tests for hydraulic pulsed cavitating jet assisted drilling

在分析水力脉冲与空化射流调制机理的基础上，设计出一种新型水力脉冲与空化射流耦合的水力脉冲空化射流发生器，通过流体脉冲扰动和自振空化效应耦合，使进入钻头的常规连续流动调制成振动脉冲流动。钻头喷嘴出口形成脉冲空化射流，产生水力脉冲、空化冲蚀和局部负压效应，从而提高井底净化和辅助破岩效果。塔里木盆地6口井的现场试验结果表明，水力脉冲空化射流钻具对钻头类型、地层特性、钻井液密度、排量、动力钻具等具有良好的适用性，机械钻速提高10．1％～53．4％。水力脉冲空化射流发生器具有性能稳定、效果好、使用寿命长等特点，完全可以满足现场的需要。水力脉冲空化射流技术将为提高深井钻速提供一种切实有效的途径，具有较好的推广应用价值。

Based on modulating pulse jet and cavitating jet, a new drilling tool is designed which couples the advantages of both pulse jet and cavitating jet. When drilling fluid flows through the tool in drilling process, the fluid is modulated to pulse and cavitate. Thus, pulse cavitating jet is formed at the outlet of the bit nozzle. Because of jet pulsation, cavitating erosion and local negative pressure effect, bottomhole rock cleaning and breaking are enhanced and penetration speed improved. The tests in six wells show good applicability of the tool to bit types, formation, drilling fluid densities, flow rates and dynamic hydraulic drilling motors, etc. As the result, penetration speeds are improved by 10. 1 to 53.4 percent and the maximum working time is about 235.5 hours in down-hole. Pulse and cavitating jet coupling will afford an effective means to improve drilling rate for deep wells.