Tapered stator designs are engineered in a positive displacement motor (PDM) power section to relieve stator stress concentrations at the lower (downhole) end of the power section in the presence of rotor tilt. A contoured stress relief (i.e. a taper) is provided in the stator to compensate for rotor tilt, where the taper is preferably more aggressive at the lower end of the stator near the bit.

A downhole motor or pump assembly that includes a housing that includes a metal. A stator that includes an elastomer compound with an uncured plasticizer is secured and sealed within the housing using an adhesive system that includes an adhesive and a dried film thickness of 2.5 mil to 7 mil. The assembly also includes a rotor rotatable within the stator. The motor or pump is operable by rotation of the rotor within the stator. In the case of a motor assembly, the motor assembly may be part of a drilling assembly that includes a drillstring and a drill bit to drill a borehole.

A rubber compound for use in a stator. The stator may be deployed in a positive displacement motor. The rubber compound includes a fiber reinforcement, wherein fibers in the fiber reinforcement create a grain direction in which “with the grain” is generally orthogonal to “across the grain”. In some embodiments, the rubber compound has a first value for 25% tensile Modulus across the grain and a second value for 25% tensile Modulus with the grain, wherein the first value is at least 10% lower than the second value. In such embodiments, the fiber reinforcement may further include a fiber loading of greater than 1.0 phr of fibers. In such embodiments, the rubber compound may further have a 25% tensile Modulus of greater than 400 psi across the grain and a 50% tensile Modulus of greater than 700 psi across the grain.

Progressing cavity devices and systems are provided. In one embodiment, a stator of a progressing cavity device includes metal plates with apertures that are rotationally offset to form a winding rotor conduit for receiving a rotor of the progressing cavity device. A layer of elastomer can be provided on edges of the apertures of the metal plates in the winding rotor conduit, and the stator can also include a gas breakout port through the metal plates to enable gas between the metal plates to escape the stator. Additional systems, devices, and methods are also disclosed.

Downhole tools for earth-boring applications may include a component of a steel material and including a bore. An inner surface defining the bore may be treated with a surface treatment. The surface treatment may include a nitrided region having nitrogen diffused into the steel material and a ceramic material adjacent to the nitrided region; the ceramic material defining the inner surface. Methods of making downhole tools for earth-boring applications may involve exposing a component of the downhole tool to an elevated temperature to heat the component in a nitrogen-rich environment. Nitrogen may be diffused into a steel material of the component and a nitrided region may be formed at one or more surfaces of the component. A ceramic material may be coated on the nitrided region of the component.

A molding method for producing a screw drill stator using an elastomer material includes: S1. sequentially roughening, cleaning and drying an inner surface of the stator tube; mixing an adhesive and a diluent, coating the mixture obtained on the inner surface, and heating it for later use; S2, uniformly coating a mold release agent on a surface of a mandrel mold, and heating or drying it naturally for later use; S3. assembling the processed stator tube and the processed mandrel mold to obtain an assembled mold; S4. performing a vacuum defoaming under negative pressure on a mixture obtained by uniformly mixing a prepolymer of the elastomer material with a defoaming agent; S5. uniformly mixing the defoamed prepolymer of the elastomer material with a curing agent, and pouring the obtained mixture into the assembled mold, sealing and curing the poured assembled mold by hierarchical heating to obtain the stator.

A mud motor, system, and method for using same are disclosed. A mud motor can include a continuously formed power section stator housing having a first end, a second end, and an internal cavity comprising a series of stator lobes and a housing portion passing. The stator lobes can extend from the first end of the power section stator housing until a first end of a transition portion. The transition portion can form a unitary combination with the stator lobes. The mud motor further includes a rotor assembly including a power section rotor having rotor lobes to be disposed completely within the internal cavity. Additional apparatuses, systems, and methods are disclosed.

The dynamic fatigue and hysteresis performances of fiber reinforced rubber compounds are compared using different plasticizers. Polymer-based fiber reinforced rubber compounds including a non-linear functionalized fatty acid ester, preferably a trimellitate, and more preferably Tris (2-Ethylhexyl) Trimellitate (TOTM) are shown to demonstrate greatly improved dynamic fatigue and hysteretic performance as compared to reference fiber reinforced rubber compounds including conventional reference plasticizers such as Di-isodecyl phthalate (DIDP).

The present invention comprises: a stator 2 that is cylindrical and has a through hole 10, the through hole 10 in the shape of a female screw and being formed at a certain pitch in the flow direction from an inlet to an outlet; and a rotor 3 that is formed in the shape of a male screw, is inserted into the through hole 10 of the stator 2 to form a transport space 11 with the inner circumferential surface of the through hole, and rotates to move a fluid from the inlet to the outlet through the transport space 11 while being inscribed on the inner circumferential surface. The volume of the transport space 11 is reduced toward the flow direction. This prevents, reliably, the occurrence of bubbles from a fluid at a downstream-side when the fluid is transported through the transport space 11 formed between the stator 2 and the rotor 3.

A stator assembly for a progressing cavity pump is provided. The stator assembly includes a number of stator laminates having a planar body defining a primary, inner passage and a number of outer passages, the outer passages disposed effectively adjacent the inner passage whereby the inner passage is at least partially defined by a band, wherein the band is outwardly flexible. The stator laminates are coupled to each other in a stack wherein the stator laminate body inner passages define a helical passage. The helical passage is a flexible helical passage.