IMPROVED DOWNHOLE TOOL

摘要

The invention relates to a downhole tool including a selectively releasable joint, a downhole drilling assembly including the downhole tool, and to a corresponding method. In one embodiment of the invention, a downhole drilling assembly (10) includes a downhole tool (12) having a first body (20, 22) and a second body (26) mounted for relative rotation; a joint part (24) for use in forming a selectively releasable joint between the second body (26) and a part (16) of the assembly coupled to the second body (26); and locking means (34) for locking the first and second bodies (20, 22; 26) relative to one another against relative rotation so as to allow a release force to be applied through the first body (20, 22) to release the releasable joint (24) and allow the tool (12) to be separated from the part (16) of the assembly (10).