Abstract: A fluid operated overshot with an outer metal mandrel internally supports a resilient internal sleeve. The sleeve telescopes over a fish to grip the fish on expanding radially inwardly. This expansion is fluid powered by applying a force to the inner sleeve to expand inwardly from a piston which compresses the sleeve, or form surrounding the inner sleeve in a concentric fluid receiving cavity.

Abstract: A milling machine is set forth for operation on a pipe string in a cased well to mill the casing. In one embodiment, an inner mandrel having a shoulder is aligned relative to a set of first cutters which are retracted. They are radially extended through slots in an outer body for cutting operations when the pipe string is rotated. Extension is accomplished by raising pump pressure to move an inner mandrel having a shoulder juxtapositioned relative to the cutters. In an alternate embodiment, the inner mandrel has two shoulders which cooperate with two separate sets of cutters wherein the first set is fully extended and the second set in only partially extended. The coil spring controlling the shoulder for the second set of cutters. The lower end of the tool body includes a constricted outlet orifice for mud flow and an alternate pathway through the inner mandrel and outer body is provided to flush cuttings and chips from the cutters.

Abstract: A milling apparatus is disclosed. The structure includes first and second upper subs threading together and having an inner axial passage. A long stinger fits in this passage and connects with a mandrel which is telescoped within an outer tubular body for a vertical or telescoping movement. The mandrel is formed with lengthwise slots, enabling independent knives to be positioned in each of the slots. The knives are engaged for controlled radial deflection by a dovetail connection, and the slots terminate at a sloping shoulder to force the individual cutters radially outwardly. An expansion chamber below the mandrel forces the mandrel upwardly with respect to the surrounding outer tubular body, causing the cutters to extend through individual lengthwise slots in the outer tubular body to the cutting position.

Abstract: A wiping tool for free fall in a drill stem is disclosed. The wiping tool is adapted to be dropped in the drill stem to wipe the inner wall. It is constructed with an elongate mandrel terminating at upper and lower subs. The upper sub supports a fishing neck and the lower sub encloses a check valve assembly. Adjustable weight means are affixed to the lower sub. Wiping is accomplished by an elongate sleeve having narrow upper and lower ends slideably mounted on the central mandrel, and the sleeve is enlarged at central portions to a diameter sufficient to wipe the wall of internal upset pipe, and wherein said sleeve is resilient, and is therefore able to reduce in diameter on passing through an internal upset and resiliently restores to the initial diameter after passing through the upset. A closed system stores incompressible fluid to keep the sleeve filled and inflated.

Abstract: A wiping tool for free fall in a drill stem is disclosed. The wiping tool is adapted to be dropped in the drill stem to wipe the inner wall. It is constructed with an elongate mandrel terminating at upper and lower subs. The upper sub supports a fishing neck and the lower stub encloses a check valve assembly. Adjustable weight means are affixed to the lower sub. Wiping is accomplished by an elongate sleeve having narrow upper and lower ends slideably mounted on the central mandrel, and said sleeve is enlarged at central portions to a diameter sufficient to wipe the wall of internal upset pipe, and wherein said sleeve is resilient, and is therefore able to reduce in diameter on passing through an internal upset and resiliently restores to the initial diameter after passing through the upset.

Abstract: A milling machine is set forth for operation on a pipe string in a cased well to mill the casing. In one embodiment, an inner mandrel having a shoulder is aligned relative to a set of first cutters which are retracted. They are radially extended through slots in an outer body for cutting operations when the pipe string is rotated. Extension is acccomplished by raising pump pressure to move an inner mandrel having a shoulder juxtapositioned relative to the cutters. In an alternate embodiment, the inner mandrel has two shoulders which cooperate with two separate sets of cutters wherein the first set is fully extended and the second set in only partially extended. The coil spring controlling the shoulder for the second set of cutters. The lower end of the tool body includes a constricted outlet orifice for mud flow and an alternate pathway through the inner mandrel and outer body is provided to flush cuttings and chips from the cutters.

Abstract: In a drill string connected to a wash pipe for retrieval of a fish in a well borehole, an apparatus comprising a connected tubular member therebetween having an internal movable sleeve. The sleeve is located close over a set of bypass ports to the exterior. The ports are selectively opened or closed; when closed, the fluid flow is directed to the fish in the wash pipe. A method of washing is set forth including the steps of controlling fluid flow so that, during running in of the wash pipe over the fish, fluid is bypassed. The bypassing occurs during the fish engagement improving speed of running in up to the time the wash pipe telescopes significantly over the fish.

Abstract: For use in a string of drill pipe terminating in drill collars and a drill bit, a shock sub is disclosed which, in the illustrated and preferred embodiment, incorporates telescoping upper and lower mandrels. The upper mandrel incorporates a pin connection and supports concentrically deployed, inner and outer tubular sleeves defining an internal cavity. The lower mandrel incorporates an upstanding sleeve which telescopes into the cavity between the sleeves of the upper mandrel. A two-chamber fluid damping system constrains movement of the lower mandrel sliding in the cavity of the upper mandrel. The two chambers are defined by meshed splines which permit telescoping movement, but which prevent relative rotational movement.

Abstract: For use in degassing drilling mud, an improved apparatus is disclosed in the illustrated and preferred embodiment which incorporates an upstanding hollow cylindrical housing having a rotatable shaft therein. The shaft is centered within the housing and supports the flights of a screw conveyor. The screw conveyor flights are not spaced evenly; they are spread at the lower end of the equipment and are closer together at the upper end of the shaft to provide variations in volume to change velocity and pressure during separation. Moreover, the flights slope downwardly. The cylindrical housing has an opening into a circular manifold at the bottom for receiving mud. Mud is introduced to the screw and is forced upwardly on rotation of the shaft. The cylindrical housing is perforated at the upper end to enable the drilling mud to spill out of the cylindrical housing and to fall into a delivery manifold.