Patent ID: 7493949
Filing Date: 2009-02-24
Classification: E21B

Abstract:
1. A subassembly for a downhole drill string comprising: a hollow body member having an outer wall and a central passage extending longitudinally from an upper end to a lower end; a plurality of blade openings in said body member; a plurality of blades adapted to outwardly project through said blade openings; a fluid inlet through said outer wall in a lower section of said body below said blade openings; a fluid outlet through said outer wall in an upper section of said body above said blade openings; a hollow, cylindrical support mandrel extending longitudinally through said central passage in said body from below said fluid inlet to above said fluid outlet and annularly spaced apart from inner walls of said body, said support mandrel supporting said blades in said blade openings with a bottom surface of said blades in engagement with an outer surface of said support mandrel; and an annular fluid flow passage in said annular space between said support mandrel and said inner walls of said body.