Abstract: Basing on the measurement of axial percussive pressure of nozzle jet, this paper investigates the effective jet distance, the jet pulse property, and the bottom hole pressure destribution of the oscillating-pulse jet-nozzled bit. The results show, under the same conditions, that the effective jet distance of pulse-jet nozzle has been raised by 150 %, and pulse amplitued by 170 %, compared with those of 3 common jet nozzle. Therefore the bottom hole pressure distributions is more advantageous to the removal of bit cuttings.

Key words: Nozzle, Drilling fluid pulse, Jet drilling theory, Jet bit, Bottom hole pressure