Patent ID: 6508317
Filing Date: 2003-01-21
Classification: E21B

Abstract:
Flow pulsing apparatus for a drill string, the apparatus comprising:a housing for location in a drill string above a drill bit, the housing defining a throughbore to permit passage of drilling fluid therethrough; a valve located in the bore and including first and second valve members each defining a respective axial flow opening and which openings are aligned to collectively define an open axial drilling fluid flow port through the valve, the first member being rotatable about a longitudinal axis of the housing to vary the alignment of the openings between a first alignment in which the openings collectively define an open axial flow port of a first open area and a second alignment in which the openings collectively define an open axial flow port of a second open area greater than said first open area to, in use, provide a varying flow therethrough and variation of the drilling fluid pressure; and drive means operatively associated with the valve for rotating the first member.