Abstract: In one embodiment, the present invention provides a reverse circulation drilling apparatus which comprises a concentric dual wall drill pipe, having a first threaded end, a second threaded end, an outer pipe and an inner pipe captured in a concentric arrangement within the outer pipe and defining an annulus therebetween. The inner pipe defines an inside passage, which is not in fluid communication with the annulus. A first means for directing an outer flow of fluid through the annulus is provide. A second means for directing an inner flow of fluid through the inside passage is also provided. The first means and the second means prevent fluid communication between the outer flow and the inner flow. The first threaded end and the second threaded end are each suitable to connect the reverse circulation drilling apparatus to another reverse circulation drilling apparatus.

Abstract: An improved stabilizing tool includes a body with a pocket, and a roller rotatably disposed in the pocket. The body includes a fluid passageway formed axially therethrough. The passageway has a first zone wherein the pressure of the fluid is relatively high and a second zone wherein the pressure is relatively low. A first conduit provides fluid communication between the first zone and an interior of the roller for the ingress of fluid to the interior, and a second conduit provides fluid communication between the interior of the roller and the second zone for the egress of the fluid back to the fluid passageway.