Abstract: The present invention is generally directed to a tool for obtaining weight-on-bit (WOB) measurements and methods of using such a tool. In one illustrative embodiment the tool comprises a body, at least one strain gauge cavity in the body, the strain gauge cavity having a strain gauge mounting surface that is located at a position such that a region of approximately zero axial strain due to downhole pressures during drilling operations exists on the mounting surface when the tool is subjected to downhole pressures during drilling operations, and a weight-on-bit strain gauge operatively coupled to the mounting face above the region of approximately zero axial strain.

Abstract: A sub-surface release plug assembly for use in cementing an outer casing annulus around a well casing comprising a top plug releasably connected to a drill string by a collet mechanism and a bottom plug releasably attached to the top plug by a sleeve assembly extending through the top plug. The assembly further comprises primary and secondary release means for releasing said plugs thereby ensuring that the plugs are released in said casing during cementing operations.