Flow pulsing device for a drilling motor

Abstract

A downhole flow pulsing device comprises a housing connected in series with a drill string and a valve with a rotating portion in the housing arranged to vary an area of a flow passage through the housing. A fluid actuated positive displacement motor drives rotation of the valve. A drive link permits the rotating portion of the valve to be optionally coupled directly to the motor of the drill string. The valve includes radially oriented rotating ports intermittently communicating with surrounding fixed ports and a bypass channel. Axial displacement of the rotating ports relative to the fixed ports and bypass channel permits amplitude of the downstream fluid pulses to be adjusted. The valve includes a number of circumferentially spaced ports which differs from a prescribed number of pressure fluctuations in the fluid for each full rotation of the rotor of the drill motor.