Abstract: A check valve for connection with the top end of a drillstring as a mud saver comprises a tubular valve member (18) which is axially shiftable within a tubular body (10) through a sleeve seal (19) which is mounted in the body (10) and which cooperates with ports in the wall of the tubular valve member (18) and which is disposed adjacent a downstream end of the tubular valve member. A compression spring (20) urges the tubular valve member (18) in the upstream direction into abutment with an upstream stop (15). The downstream end of the tubular valve member is closed by means of a frangible glass disc (21). The sleeve seal (19) is also axially shiftable in the body (10) in an upstream direction away from a downstream stop (17) and the compression spring (20) urges the sleeve seal (19) in the downstream direction. In a compact arrangement, the tubular valve member (18) is housed within an upstream hollow pin (30) of a saver sub particularly suited to a top drive arrangement.

Abstract: A downhole steering tool comprises a hollow mandrel (11), an independently rotatable sleeve (12) extending over a portion of the mandrel (11), steering plungers (26) carried by the sleeve (12) and extendable and retractable laterally to and from pressure contact with the hole wall (28) for steering a drill below the tool when in use, releasable locking means (14) for locking the sleeve (12) to the mandrel (11) rotationally, and fluid control means (15) operable to direct to the locking means (14) and the steering plungers (26) a portion from fluid circulation through the mandrel (11) to release the locking means (14) and to extend the steering plungers (26) by means of pressure of the fluid.

Abstract: A wash-over type down hole retrieving device or fishing tool is described, consisting of a hollow cylindrical body having an open lower end. The body has concentric inner and outer walls, defining an annular space in which an annular piston can force down an annular sleeve of a malleable alloy having downwardly extending finger-like formations. The inside of the lower end of the outer wall is of cupped configuration effective to deflect the fingers inwards and over the open end of the body so as to trap and retain an object for retrieval. The annular piston is forced down hydraulically by dropping a diverter ball valve. Cutting teeth are optionally provided on the outer periphery of the lower end of the outer wall, on a detachable shoe.