Patent ID: 7140454

Claim:
A well drilling bit comprising: a bit body attachable to a tubular drill string, which bit body is internally provided with a passageway other than a nozzle, which passageway provides fluid communication, when the drill string is attached to the bit body, between the interior of the drill string and the exterior of the bit body; a closure element for selectively closing the passageway; and one or more chip-making elements, wherein the chip-making elements comprise one or more roller-cones, wherein the closure element is releasably connectable to the bit body, and outwardly movable from a closing position, in which the closure element is connected to the bit body, to an opening position, in which the closure element is disconnected from the bit body, wherein the closure element includes at least one of the roller-cones and a cone leg, and wherein the passageway comprises a section that is not co-axial with the central longitudinal axis.