Abstract: The application of oscillation impacter for drilling in petroleum industry is becoming more and more widely, which have turned to be the key technology for improving the rate of penetration. Structure, working principle of oscillation impacter, generation of the water hammer and vibration mechanism are analyzed. Water hammer force and amplitude are also computed. The results show that water hammer force and the valve opening is inversely proportional, frequency of water hammer is proportional to the motor collar revolutions per minute, dual water hammer is produced by up and down valves together. Dual water hammer may be helpful for rock breaking. The gentle axial vibration resolves sticking and heavy bottom hole assembly hang in horizontal or extended reach wells, helps tool face control and extends bit life.

Key words: backing pressure, improve rate of penetration, oil-drilling, oscillation impulse, water hammer