An extruder screw includes an extruder shaft and at least one extruder segment. The extruder shaft has a prismatic mandrel having external teeth and a longitudinal mandrel axis. The extruder segment has internal teeth and a longitudinal internal-teeth axis and can be slid onto the mandrel, such that the extruder segment can be connected to the mandrel for rotation therewith. The internal teeth have a profile having a meshing profile and, in an inner area between the first and second end faces of the extruder segment, include a prismatic main profile that has a main cross-section. Furthermore, the internal teeth of the extruder segment have an edge profile adjacent to at least one end face of the extruder segment, which edge profile has a smaller edge cross-section than the main profile at least in the area of the meshing profile.

A mud motor stator or a pump comprising of a tubular outer portion; a number of lobes extending radially inwardly from the tubular outer portion, at least one of which comprises a skeletal structure and method for producing a mud motor stator or a pump comprising of placing material and bonding the material together in a pattern dictated by the design shape of the stator or pump.

A mud motor stator or a pump comprising of a tubular outer portion; a number of lobes extending radially inwardly from the tubular outer portion, at least one of which comprises a skeletal structure and method for producing a mud motor stator or a pump comprising of placing material and bonding the material together in a pattern dictated by the design shape of the stator or pump.

A stator for a downhole motor configured for use in a downhole environment. includes an inner tubular member formed from a first metallic material having an outer surface and a helically lobed inner surface, and an outer tubular member comprising a second metallic material that is different from the first metallic material. The inner tubular member is connected to the outer tubular member by compressive force passing from the outer tubular member through the inner tubular member to a rigid mandrel removably disposed within the inner tubular member. The inner tubular member and the outer tubular member form the stator of the downhole motor.

A rotor for a mud motor includes a core having a first outer shape, and a shell positioned around the core, the shell having a second outer shape that is different from the first outer shape, the second outer shape defining one or more lobes and one or more cavities that are configured to engage a bore of a stator during rotation of the rotor relative to the stator. A thickness of the shell varies as proceeding around the core, from a non-zero minimum thickness to a maximum thickness.

A rotor for a mud motor includes a core having a first outer shape, and a shell positioned around the core, the shell having a second outer shape that is different from the first outer shape, the second outer shape defining one or more lobes and one or more cavities that are configured to engage a bore of a stator during rotation of the rotor relative to the stator. A thickness of the shell varies as proceeding around the core, from a non-zero minimum thickness to a maximum thickness.

A stator for a mud motor and methods for manufacturing and using the same, of which one such method includes obtaining a mud motor having a stator made at least partially from a rubber. At least a portion of the rubber is cured by at most about 90%. The method also includes deploying the mud motor into a well as part of a drill string. The rubber is not further cured prior to deploying the mud motor into the well. The method further includes generating torque using the mud motor by pumping a mud through the stator.

A stator for a downhole motor configured for use in a downhole environment. includes an inner tubular member formed from a first metallic material having an outer surface and a helically lobed inner surface, and an outer tubular member comprising a second metallic material that is different from the first metallic material. The inner tubular member is connected to the outer tubular member by compressive force passing from the outer tubular member through the inner tubular member to a rigid mandrel removably disposed within the inner tubular member. The inner tubular member and the outer tubular member form the stator of the downhole motor.

A method of making a stator includes positioning an inner tubular member having an inner surface within an outer tubular member, installing a rigid mandrel within the inner tubular member, and applying a compressive force to at least one of the inner tubular member and the outer tubular member.

An enhanced elastomeric stator assembly and method of making the same is disclosed. The elastomeric stator may be structurally, thermally, and/or chemically enhanced through the incorporation of graphene particles, cross-linkable polymers, coupling agents that extend cross-links, and by the reduction of filler material. The graphene particles can be incorporated in functionalized or non-functionalized form or in a combination thereof, the functionalized graphene increasing the number of cross-links in the overall structure, thereby enhancing the structural robustness of the elastomeric stator. The compound can be formulated to have a relatively low viscosity and other characteristics that allow the material to flow through a mould cavity.