关键词: 空化起始, 空化射流, 喷嘴, 钻井速度

Abstract: It’s of great significance to research into the inception ability of nozzles and enhancement of their rock erosion effect to improve penetration rate of drilling deep wells. Self-resonant cavitating nozzle is designed with the principle based on the theory of fluid transients and hydro-acoustics. The lab investigation demonstrates that higher inception cavitation number and stronger cavitation effect under higher ambient pressure can be achieved in deeper bottom hole or under higher ambient pressure with self-resonant cavitating nozzle than the conventional cone-shaped nozzle, and the enhanced inception cavitation number can be as high as 1.67 while that of cone-shape nozzle is usually with 0.54 as the highest. Field tests are proved that the bit with self-resonating nozzles can significantly increase the footage of the bit, improving the penetration rate.

Key words: Cavitation jet, Cavitation inception, Drilling speed, Nozzle