Patent ID: 9068400
Filing Date: 2015-06-30
Classification: E21B

Abstract:
1. A method for controlling a resonance enhanced rotary drill comprising a rotary drill bit and an oscillator for applying axial oscillatory loading to the rotary drill bit, the method comprising: controlling frequency (f) of the oscillator in the resonance enhanced rotary drill whereby the frequency (f) is maintained in the range where D is diameter of the rotary drill bit, U s is compressive strength of material being drilled, A is amplitude of vibration, m is vibrating mass, and S f is a scaling factor greater than 1; and controlling dynamic force (F where D eff is an effective diameter of the rotary drill bit, U s is a compressive strength of material being drilled, and S Fd is a scaling factor greater than 1, wherein the frequency (f) and the dynamic force (F