Well casing installation and removal apparatus and method

摘要

A downhole well drilling apparatus includes an above-ground mast and an axially elongated generally cylindrical pneumatic hammer drill supported by the mast and mounted in an axially vertical above-ground position. An installation and removal adapter mounted on the lower end of the pneumatic hammer drill couples the hammer drill to a pipe string and maintains a movable part of the hammer drill in an operative condition at all times thereby enabling the hammer drill to operate while rotational torque and upward directed force are simultaneously applied to the operating hammer drill by the apparatus during removal of a casing from a downhole position. Hammer operation is controlled by a manually operable air supply valve.