Abstract: A variable gauge drilling apparatus and a method for assembling a variable gauge drilling apparatus for insertion in a subject borehole. The variable gauge drilling apparatus includes: an apparatus housing having a housing size which is suitable for insertion in a subject borehole which has a subject borehole size within a design range of borehole sizes; a plurality of interchangeable borehole engaging devices having different device sizes for mounting on the apparatus housing to provide the drilling apparatus with a drilling apparatus size within a range of drilling apparatus sizes, wherein the range of drilling apparatus sizes is compatible for use of the drilling apparatus within the design range of borehole sizes; and a universal borehole engaging device mount located on the apparatus housing, wherein the mount is configured to accept for mounting any one of the plurality of interchangeable borehole engaging devices.

Abstract: A fail-safe tubular receiving member for use in combination with a latch assembly to longitudinally support and rotationally orient the latch assembly in a wellbore. The latch assembly includes at least one outwardly biased, radially movable latch member which is receivable within a bore of the receiving member. A first recessed area and a second recessed area, accessible from the first recessed area, are defined by the bore. The first recessed area defines a first increased radial distance and is configured so that upon longitudinal alignment of the latch member and the first recessed area, the latch member moves radially outward for receipt in the first recessed area to support the latch assembly longitudinally such that longitudinal movement of the latch assembly relative to the receiving member further downhole is prevented.