Nano particle reinforced polymer element for stator and rotor assembly

Abstract

A nano particle reinforced polymer element of a stator and rotor assembly for a power section of a positive displacement fluid motor or a progressive cavity pump. Nano-sized particles are blended with an uncured polymer to improve the physical and chemical properties of the polymer. The use of nano-sized particles reduces the quantity of reinforcement material required to manufacture the polymer for the stator and rotor assembly and lowers the viscosity of the uncured polymer to improve manufacturing characteristics. The use of chemically functionalized nano particles improves the chemical and physical characteristics of the polymer.

Description

FIELD OF THE INVENTION[0001]This invention relates, in general, to a polymer element of a stator and rotor assembly for power sections of positive displacement downhole fluid motors and progressive cavity pumps and, in particular, to an improved polymer element of a stator or rotor element comprised of a nano particle reinforced polymer internally disposed in a stator lining or disposed as a uniform compliant layer along a rotor surface.BACKGROUND OF THE INVENTION[0002]Without limiting the scope of the present invention, its background will be described with reference to stator and rotor assemblies of power sections of positive displacement fluid motors and progressive cavity pumps, as examples.[0003]A typical power section of a positive displacement fluid motor comprises a helical-shaped steel rotor that turns rotatably about the centerline of a polymer-lined stator and rotor assembly. A typical stator is a steel tube, lined with a bonded polymer with a helical-shaped inner cavity....

AI Technical Summary

Benefits of technology

[0019]The present invention discloses a stator and rotor assembly of a power section of a positive displacement fluid motor or a progressive cavity pump that includes a polymer element wherein the polymer is a polymer matrix reinforced with nano-sized particles to create a nano composite material with improved mechanical, thermal, physical, chemical, and processing properties.

[0020]The polymer element may be manufactured from a nano particle polymer composite that includes a polymer host and one or more of a plurality of nano-sized structures. Introduction of nano particles to the uncured polymer may improve the physical properties of the polymer by reducing processing viscosity, improving impact strength, improving stress relaxation resistance, improving compression set properties, increasing tear strength, reducing creep, increasing resistance to thermal and hysteresis failure, and improving resistance to chemical degradation of the polymer.

[0029]Incorporation of nano particles in the polymer improves the particle reinforced polymer matrix by reducing processing viscosity, improving impact strength, improving stress relaxation resistance, improving compression set properties, increasing tear strength, increasing resistance to thermal and hysteresis, reducing heat buildup failure, increasing thermal conductivity, reducing creep, improving resilience and abrasion resistance, and improving resistance to chemical degradation of the polymer.

[0030]Nano particle reinforced polymers generally require lesser amounts of filler material than traditional fillers to achieve comparable physical properties. The lesser amount of nano material required to reinforce a cured polymer has a concomitant effect of lowering the uncured viscosity of the polymer and thereby improving the ability to manufacture longer and thinner profiles of polymer stator elements and improving physical properties at elevated temperatures.

[0031]In another aspect, the nano particle composite structures may be chemically functionalized to enhance the effective surface area of the composite structure and improve the availability of potential chemical reactions or catalysis sites for chemical functional groups on the nano composite structure and increase the interaction between the polymer matrix and the nano particles.

Problems solved by technology

Slip results in speed and power reduction of a power section until, at some point, the power section stalls, allowing substantially all fluid to bypass the interface between the rotor and the stator with no resultant rotation produced by the power section.

Failure of the polymer element of a power section of a positive displacement fluid motor or a progressive cavity pump typically occurs due to high mechanical loading, polymer fatigue, incompatibility of the fluid and polymer, or high temperature effects on the polymer element.

Failure may be associated with a reduction in the performance of the polymer element or with catastrophic failure.

Mechanical failure of the polymer element occurs when the polymer is subject to conditions that exceed the critical strain limit or when the polymer is subject to excessive cyclic loading.

Excessive polymer temperatures generally result from high downhole temperature, hysteresis heat buildup caused by repeated flexing of the polymer by the lobes rotor and pressurized fluid or a combination and may lead to failure of the polymer element or the bond between the polymer and the metal surface of a stator and rotor assembly.

Excessive operating temperature may cause expansion of the polymer that increases the compressive interference between the rotor and the stator, further increasing hysteresis heat generation and wear.

Certain chemicals may react with the polymer element of the stator and rotor assembly and cause degradation of the polymer or the bond between the polymer and the metal surface by weakening the molecular bonding of the polymer.

For example, synthetic oils or aromatic compounds found in drilling fluids and drilling fluids buffered with chemicals or composed of high alkalinity brine solutions may cause degradation of the polymer.

Uniform thickness of the polymer element of the stator may be difficult to achieve due to the length of the stator housing into which the uncured polymer is injected and the relatively high viscosity of the uncured polymer.

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