BIT PACKER FOR DUAL TUBE DRILLING

摘要

A bit packer for use with a string of dual concentric drill pipe, having inner and outer tubular members concentrically arranged to mate with the inner and outer pipes of the drill string to provide an annular conduit for fluid from surface to bit and a central conduit for fluid and cuttings from bit to surface, is particularly characterized by flexible packing means mounted slidably and rotatably on the outer tubular member. The packing means deform against the hole wall to seal the annular space between the outer member and the hole wall. Upper and lower ports provide fluid communication between the annular conduit and the annular space; when the packer is moved downwardly in the hole the packing means slides upwardly to close the upper port and open the lower port; when the packer is moved upwardly in the hole, the converse occurs. A milling collar is provided above the packing means.