Patent ID: 8272456

Claim:
A system for drilling a well having a wellbore comprising: a first pipe string positioned in the wellbore, a first annulus present between the first pipe string and the wellbore; a second pipe string, smaller in diameter than the first pipe string, positioned within the first pipe string to form a second annulus between the first pipe string and the second pipe string, the second pipe string configured to be attached to a drill bit; and a fluid source at or near a surface of the well in communication with one of the first annulus and the second annulus to deliver a first fluid to the other of the first annulus and the second annulus at a downhole location uphole of the drill bit; wherein the other of the first annulus and the second annulus receives a drilling fluid from the second pipe string and permits delivery of a mixture of the drilling fluid and the first fluid from the downhole location to the surface of the well; wherein an inner diameter of the first pipe string is sized to be less than a diameter of the drill bit; wherein the first pipe string and the second pipe string are each rotated at different speeds; wherein in operation, the second pipe string is independently and axially moveable relative to the first pipe string.