Patent ID: 6971458
Filing Date: 2005-12-06
Classification: E21B

Abstract:
1. A drill bit for drilling a borehole into an earth formation, the drill bit having a central longitudinal axis and a bottom surface facing the borehole bottom during drilling with the drill bit, the drill bit comprising primary fluid injection means arranged at the bottom surface and located at a selected radial distance from the central longitudinal axis, the primary fluid injection means being arranged to eject a primary stream of fluid into the borehole, the primary stream having a component in a plane substantially transverse to the drill bit axis, directed from the fluid injection means to the central longitudinal axis, the drill bit further comprising secondary fluid injection means arranged at the bottom surface and spaced from the primary fluid injection means, the secondary fluid injection means being arranged to eject a secondary stream of fluid into the borehole, the secondary stream having a component in said transverse plane, directed substantially opposite the direction of said component of the primary stream of fluid in a cross flow mode.