Abstract: Systems and methods for producing forced axial vibration of a drillstring. Systems include a cam housing positioned above a drill bit in a drillstring, a rotatable cam positioned internal of the cam housing, the rotatable cam having at least one cam surface exhibiting reciprocating axial movement upon rotation of the rotatable cam, and a non-rotatable cam follower positioned internal surface of the cam housing and having at least one cam follower surface engaging the cam surface. The cam follower transfers the reciprocating axial movement to the drill bit. The rotatable cam is rotated by a fluid-powered positive displacement power section positioned above and mechanically attached to the rotatable cam in the drillstring to effect the rotation of the rotatable cam, and thus effect the reciprocating axial movement of the drill bit.

Abstract: Systems and methods for producing forced axial vibration of a drillstring. Systems include a cam housing positioned above a drill bit in a drillstring, a rotatable cam positioned internal of the cam housing, the rotatable cam having at least one cam surface exhibiting reciprocating axial movement upon rotation of the rotatable cam, and a non-rotatable cam follower positioned internal surface of the cam housing and having at least one cam follower surface engaging the cam surface. The cam follower transfers the reciprocating axial movement to the drill bit. The rotatable cam is rotated by a fluid-powered positive displacement power section positioned above and mechanically attached to the rotatable cam in the drillstring to effect the rotation of the rotatable cam, and thus effect the reciprocating axial movement of the drill bit.