An insert for forming an end connection in a uni-axial composite material, and an end connection comprising at least one insert, is disclosed. The insert comprises a sleeve which comprises a plurality of fibers having a multi-axial arrangement. At least a portion of the interior surface of the sleeve comprises a thread formation. A method of forming an end connection in a uni-axial composite material is also disclosed. The method comprises providing a sleeve comprising a plurality of fibers having a multi-axial arrangement and providing a thread formation on at least a portion of the interior surface of the sleeve. The sleeve is positioned and secured within the uni-axial composite material.

Methods for improving adhesion or bonding between materials used in forming components of directional drilling assemblies, such as rotors and stators, are provided. A surface of a component may be treated, such as through cleaning, etching and/or activating a surface. The use of plasma treatment may enhance the adhesion between the surfaces and/or materials to be bonded, thereby reducing the degradation or mechanical failure of these materials in oilfield applications.

A rubber compound for use in a stator. The rubber compound includes a fiber reinforcement, which may include fibrillated fibers in some embodiments, and short chop fibers in others. Fibers in the fiber reinforcement create a grain direction. 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 embodiments, the fiber reinforcement may include a fiber loading of greater than 1.0 phr of fibers. In embodiments, the rubber compound may 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. In embodiments, at least some of the fibers may have a Modulus greater than 2.0 GPa.

A rubber compound for use in a stator. The rubber compound includes fibers made from at least one material type selected from the group consisting of: (a) meta-aramid; (b) para-aramid; (c) polyester; (d) polyamide; (e) cotton; (f) rayon; and (g) glass. Fibers in the fiber reinforcement create a grain direction. 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 embodiments, the fiber reinforcement may include a fiber loading of greater than 1.0 phr of fibers. In embodiments, the rubber compound may 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.

The disclosure relates to a screw pump comprising: a casing with an inlet, an outlet and a flow chamber between the inlet and the outlet; and at least two screws housed in the flow chamber to force a fluid flow through the flow chamber from the inlet to the outlet; wherein at least one of the screws comprises a lubricated polymer material.

The disclosure relates to a screw pump comprising: a casing with an inlet, an outlet and a flow chamber between the inlet and the outlet; and at least two screws housed in the flow chamber to force a fluid flow through the flow chamber from the inlet to the outlet; wherein at least one of the screws comprises a lubricated polymer material.