Smith International, Inc.

Neyrofor-Weir Limited

Roy Powell

Andrew McPherson Downie

Edward Docherty Scott

A downhole tool including a selectively releasable joint, a downhole drilling assembly including the downhole tool, and a corresponding method. In one embodiment of the invention, a downhole drilling assembly includes a downhole tool having a first body and a second body mounted for relative rotation; a joint part for use in forming a selectively releasable joint between the second body and a part of the assembly coupled to the second body; and one or more locking member(s) for locking the first and second bodies relative to one another against relative rotation so as to allow a release force to be applied through the first body to release the releasable joint and allow the tool to be separated from the part of the assembly.

Downhole tool

A stabilization device for a down-hole motor for use in drilling operations for example in oil-fields to control any tendency for spiralling of the tool bit during the drilling action and to permit steering by a 'orientate and rotate' technique. In an example of the device, an end portion of a motor shaft (26) projects from a motor body (20), the projecting portion being comprised of an attachment apparatus or bit box (28) by which a tool bit (38) is connected for rotation. The bit box (28) may be separable from the shaft (26) or may be integrally formed therewith, but, is provided with a stabiliser means (32) in the form of part-helical vanes surrounding the bit box (28). The bit (38), when secured in the box (28), is located immediately adjacent the stabilising vanes (32) for maximum control; additionally, stabiliser vanes (22,24) may be provided on the motor body portion (20) and, if required, on the selected tool bit.

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Estes Park, CO, United States of America

Roy Powell