U.S. patent application number 12/002710 was filed with the patent office on 2009-06-18 for nano particle reinforced polymer element for stator and rotor assembly.
This patent application is currently assigned to HALLIBURTON ENERGY SERVICES, INC., A DELAWARE CORPORATION. Invention is credited to Thomas Wayne Ray, Jeremy Buc Slay.
Application Number | 20090152009 12/002710 |
Document ID | / |
Family ID | 40510441 |
Filed Date | 2009-06-18 |
United States Patent
Application |
20090152009 |
Kind Code |
A1 |
Slay; Jeremy Buc ; et
al. |
June 18, 2009 |
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.
Inventors: |
Slay; Jeremy Buc; (Fort
Worth, TX) ; Ray; Thomas Wayne; (Tyler, TX) |
Correspondence
Address: |
LAWRENCE R. YOUST;Lawrence Youst PLLC
2900 McKinnon, Suite 2208
DALLAS
TX
75201
US
|
Assignee: |
HALLIBURTON ENERGY SERVICES, INC.,
A DELAWARE CORPORATION
Houston
TX
|
Family ID: |
40510441 |
Appl. No.: |
12/002710 |
Filed: |
December 18, 2007 |
Current U.S.
Class: |
175/107 ;
418/178; 418/61.3 |
Current CPC
Class: |
E21B 4/02 20130101; F04C
2/1071 20130101; C08K 7/24 20130101; C08K 3/041 20170501; F01C
1/107 20130101; F04C 15/0015 20130101; C08K 5/549 20130101; E21B
43/128 20130101; C08K 3/041 20170501; C08L 101/00 20130101 |
Class at
Publication: |
175/107 ;
418/61.3; 418/178 |
International
Class: |
E21B 4/02 20060101
E21B004/02; F01C 1/107 20060101 F01C001/107; F04C 18/107 20060101
F04C018/107; F04C 15/00 20060101 F04C015/00; F04C 2/107 20060101
F04C002/107 |
Claims
1. A stator and rotor assembly comprising: a stator having an inner
surface; an inner core disposed within the inner surface of the
stator and defining a cavity, the inner core comprising a polymer
material having a plurality of nano particles integrated therein;
and a rotor disposed within the cavity, operable to rotate within
the inner core.
2. The stator and rotor assembly as recited in claim 1, wherein the
stator further comprises a substantially cylindrical inner
surface.
3. The stator and rotor assembly as recited in claim 1, wherein the
rotor further comprises a spiral rotor.
4. The stator and rotor assembly as recited in claim 1, wherein the
rotor further comprises a helical rotor.
5. The stator and rotor assembly as recited in claim 1, wherein the
stator and rotor assembly is part of a positive displacement fluid
motor.
6. The stator and rotor assembly as recited in claim 1, wherein the
stator and rotor assembly is part of a progressive cavity pump.
7. The stator and rotor assembly as recited in claim 1, wherein the
polymer material is selected from an elastomer, a thermoset and a
thermoplastic.
8. The stator and rotor assembly as recited in claim 1, wherein the
polymer material further comprises an elastomer selected from the
group consisting of nitrile, carboxylated acrylonitrile butadiene,
hydrogenated acrylonitrile butadiene, carboxylated hydrogenated
acrylonitrile butadiene, hydrogenated carboxylated acrylonitrile
butadiene, tetrafluoroethylene and propylene, perfluoroelastomers,
ethylene propylene, ethylene propylene diene, polychloroprene
rubber, natural rubber, polyether eurethane and styrene butadiene
rubber.
9. The stator and rotor assembly as recited in claim 1, wherein the
polymer material further comprises a thermoplastic selected from
the group consisting of polyphenylene sulfides,
polyetherketone-ketones, polyetheretherketones, polyetherketones
and polytetrafluorethylenes.
10. The stator and rotor assembly as recited in claim 1, wherein
the nano particles further comprise nano clays.
11. The stator and rotor assembly as recited in claim 1, wherein
the nano particles further comprise carbon nano fibers.
12. The stator and rotor assembly as recited in claim 1, wherein
the nano particles are selected from the group consisting of single
wall carbon nano tubes, multi-wall carbon nano tubes and carbon
nano tube arrays.
13. The stator and rotor assembly as recited in claim 1, wherein
the nano particles are selected from the group consisting of
polysilane resins, polycarbosilane resins, polysilsesquioxane
resins and polyhedral oligomeric silsesquioxane resins.
14. The stator and rotor assembly as recited in claim 1, wherein
the nano particles are in the range from approximately 0.1
nanometers to approximately 500 nanometers, at the least
dimension.
15. The stator and rotor assembly as recited in claim 1, wherein
the nano particles are in the range from approximately 0.5
nanometers to approximately 100 nanometers, at the least
dimension.
16. The stator and rotor assembly as recited in claim 1, wherein
the nano particles are chemically functionalized.
17. A stator and rotor assembly comprising: a stator having an
inner surface; an inner core disposed within the inner surface of
the stator and defining a cavity, the inner core comprising a
polymer host material having a plurality of nano structures
integrated therein, the nano structures selected from the group
consisting of polysilane resins, polycarbosilane resins,
polysilsesquioxane resins, polyhedral oligomeric silsesquioxane
resins, monomers, polymers and copolymers of any of these resins,
carbon nanotubes and any of the preceding nano structures that are
chemically functionalized; and a rotor disposed within the cavity,
operable to rotate within the inner core.
18. The stator and rotor assembly as recited in claim 17, wherein
the stator further comprises a substantially cylindrical inner
surface.
19. The stator and rotor assembly as recited in claim 17, wherein
the rotor further comprises a spiral rotor.
20. The stator and rotor assembly as recited in claim 17, wherein
the rotor further comprises a helical rotor.
21. The stator and rotor assembly as recited in claim 17, wherein
the stator and rotor assembly is part of a positive displacement
fluid motor.
22. The stator and rotor assembly as recited in claim 17, wherein
the stator and rotor assembly is part of a progressive cavity
pump.
23. The stator and rotor assembly as recited in claim 17, wherein
the polymer material is selected from an elastomer, a thermoset and
a thermoplastic.
24. The stator and rotor assembly as recited in claim 17, wherein
the polymer material further comprises an elastomer selected from
the group consisting of nitrile, carboxylated acrylonitrile
butadiene, hydrogenated acrylonitrile butadiene, carboxylated
hydrogenated acrylonitrile butadiene, hydrogenated carboxylated
acrylonitrile butadiene, tetrafluoroethylene and propylene,
perfluoroelastomers, ethylene propylene, ethylene propylene diene,
polychloroprene rubber, natural rubber, polyether eurethane and
styrene butadiene rubber.
25. A stator and rotor assembly comprising: a stator having an
inner surface; an inner core disposed within the inner surface of
the stator and defining a cavity, the inner core comprising an
elastomer host material and chemically functionalized carbon
nanotubes; and a rotor disposed within the cavity, operable to
rotate within the inner core.
26. The downhole tool system as recited in claim 25 wherein the
elastomer host material further comprises a copolymer of
acrylonitrile and butadiene.
27. The downhole tool system as recited in claim 25 wherein the
elastomer host material is selected from the group consisting of
acrylonitrile butadiene, carboxylated acrylonitrile butadiene,
hydrogenated acrylonitrile butadiene, highly saturated nitrile,
carboxylated hydrogenated acrylonitrile butadiene, hydrogenated
carboxylated acrylonitrile butadiene, ethylene propylene, ethylene
propylene diene, tetrafluoroethylene and propylene, fluorocarbon
and perfluorocarbon.
28. The downhole tool system as recited in claim 25 wherein the
elastomer host material and the nanomaterial have interfacial
interactions.
29. The downhole tool system as recited in claim 25 wherein the
nanomaterial structurally complements the elastomer host
material.
30. The downhole tool system as recited in claim 25 wherein the
nanomaterial chemically complements the elastomer host
material.
31. The downhole tool system as recited in claim 25 wherein the
nanomaterial structurally and chemically complements the elastomer
host material.
32. The stator and rotor assembly as recited in claim 25 wherein
the stator and rotor assembly is part of a positive displacement
fluid motor.
33. The stator and rotor assembly as recited in claim 25 wherein
the stator and rotor assembly is part of a progressive cavity
pump.
34. A stator and rotor assembly comprising: a stator having an
inner surface and defining a cavity; a rotor disposed within the
cavity, operable to rotate within the cavity; and a polymer layer
disposed exteriorly on the rotor, the polymer layer having a
plurality of nano particles integrated therein.
35. The stator and rotor assembly as recited in claim 34, wherein
the stator and rotor assembly is part of a positive displacement
fluid motor.
36. The stator and rotor assembly as recited in claim 34, wherein
the stator and rotor assembly is part of a progressive cavity
pump.
37. The stator and rotor assembly as recited in claim 34, wherein
the polymer layer is formed from a material selected from an
elastomer, a thermoset and a thermoplastic.
38. The stator and rotor assembly as recited in claim 34, wherein
the polymer layer is formed from an elastomer selected from the
group consisting of nitrile, carboxylated acrylonitrile butadiene,
hydrogenated acrylonitrile butadiene, carboxylated hydrogenated
acrylonitrile butadiene, hydrogenated carboxylated acrylonitrile
butadiene, tetrafluoroethylene and propylene, perfluoroelastomers,
ethylene propylene, ethylene propylene diene, polychloroprene
rubber, natural rubber, polyether eurethane and styrene butadiene
rubber.
39. The stator and rotor assembly as recited in claim 34, wherein
the polymer layer is formed from a thermoplastic selected from the
group consisting of polyphenylene sulfides,
polyetherketone-ketones, polyetheretherketones, polyetherketones
and polytetrafluorethylenes.
40. The stator and rotor assembly as recited in claim 34, wherein
the nano particles further comprise carbon nano fibers.
41. The stator and rotor assembly as recited in claim 34, wherein
the nano particles are selected from the group consisting of single
wall carbon nano tubes, multi-wall carbon nano tubes and carbon
nano tube arrays.
42. The stator and rotor assembly as recited in claim 34, wherein
the nano particles are selected from the group consisting of
polysilane resins, polycarbosilane resins, polysilsesquioxane
resins and polyhedral oligomeric silsesquioxane resins.
43. The stator and rotor assembly as recited in claim 34, wherein
the nano particles are chemically functionalized.
44. A stator and rotor assembly comprising: a stator having an
inner surface and defining a cavity; a rotor disposed within the
cavity, operable to rotate within the cavity; and a polymer layer
disposed exteriorly on the rotor, the polymer layer having a
plurality of nano particles integrated therein, the nano particles
selected from the group consisting of polysilane resins,
polycarbosilane resins, polysilsesquioxane resins, polyhedral
oligomeric silsesquioxane resins, monomers, polymers and copolymers
of any of these resins, carbon nanotubes and any of the preceding
nano structures that are chemically functionalized.
45. A stator and rotor assembly comprising: a stator having an
inner surface and defining a cavity; a rotor disposed within the
cavity, operable to rotate within the cavity; and a elastomer layer
disposed exteriorly on the rotor, the elastomer layer having a
plurality of chemically functionalized carbon nanotubes integrated
therein.
46. A stator and rotor assembly comprising: a stator having an
inner surface with a polymer layer disposed thereon defining a
cavity; and a rotor disposed within the cavity and operable to
rotate within the cavity, the rotor having a polymer layer disposed
exteriorly thereon; wherein the polymer layer of the stator and the
polymer layer of the rotor each have a plurality of nano particles
integrated therein.
47. The stator and rotor assembly as recited in claim 46, wherein
the stator and rotor assembly is part of a positive displacement
fluid motor.
48. The stator and rotor assembly as recited in claim 46, wherein
the stator and rotor assembly is part of a progressive cavity
pump.
49. The stator and rotor assembly as recited in claim 46, wherein
the polymer layer is formed from a material selected from an
elastomer, a thermoset and a thermoplastic.
50. The stator and rotor assembly as recited in claim 46, wherein
the polymer layer is formed from an elastomer selected from the
group consisting of nitrile, carboxylated acrylonitrile butadiene,
hydrogenated acrylonitrile butadiene, carboxylated hydrogenated
acrylonitrile butadiene, hydrogenated carboxylated acrylonitrile
butadiene, tetrafluoroethylene and propylene, perfluoroelastomers,
ethylene propylene, ethylene propylene diene, polychloroprene
rubber, natural rubber, polyether eurethane and styrene butadiene
rubber.
51. The stator and rotor assembly as recited in claim 46, wherein
the polymer layer is formed from a thermoplastic selected from the
group consisting of polyphenylene sulfides,
polyetherketone-ketones, polyetheretherketones, polyetherketones
and polytetrafluorethylenes.
52. The stator and rotor assembly as recited in claim 46, wherein
the nano particles further comprise carbon nano fibers.
53. The stator and rotor assembly as recited in claim 46, wherein
the nano particles are selected from the group consisting of single
wall carbon nano tubes, multi-wall carbon nano tubes and carbon
nano tube arrays.
54. The stator and rotor assembly as recited in claim 46, wherein
the nano particles are selected from the group consisting of
polysilane resins, polycarbosilane resins, polysilsesquioxane
resins and polyhedral oligomeric silsesquioxane resins.
55. The stator and rotor assembly as recited in claim 46, wherein
the nano particles are chemically functionalized.
56. A stator and rotor assembly comprising: a stator having an
inner surface with a polymer layer disposed thereon defining a
cavity; and a rotor disposed within the cavity and operable to
rotate within the cavity, the rotor having a polymer layer disposed
exteriorly thereon; wherein the polymer layer of the stator and the
polymer layer of the rotor each have a plurality of nano particles
integrated therein, the nano particles selected from the group
consisting of polysilane resins, polycarbosilane resins,
polysilsesquioxane resins, polyhedral oligomeric silsesquioxane
resins, monomers, polymers and copolymers of any of these resins,
carbon nanotubes and any of the preceding nano structures that are
chemically functionalized.
57. A stator and rotor assembly comprising: a stator having an
inner surface with a polymer layer disposed thereon defining a
cavity; and a rotor disposed within the cavity and operable to
rotate within the cavity, the rotor having a polymer layer disposed
exteriorly thereon; wherein the polymer layer of the stator and the
polymer layer of the rotor each have a plurality of chemically
functionalized carbon nanotubes integrated therein.
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. High pressure fluid flows through
the power section of the positive displacement fluid motor causing
the rotor to turn rotatably within the stator. The positive
displacement fluid motor converts the hydraulic energy of high
pressure fluid to mechanical energy in the form of torque output at
the rotor; for example, to turn a drill bit.
[0004] The rotor is typically a steel helix with a circular cross
section with a smooth hard surface for wear resistance. The rotor
is disposed inside the stator and a plurality of cavities defined
by a seal plane between the rotor and the helical curve of the
polymer core of the stator. As the rotor turns inside the stator,
the seal plane between the rotor surface and the polymer lining of
the stator rotates around the centerline of the stator, advancing
the cavities lengthwise along the stator and rotor assembly. Each
of the cavities is sealed from adjacent cavities by the seal
plane.
[0005] The pressure differential that may be sustained across an
individual stage of a power section is improved by maintaining a
compression interference between the rotor and the stator.
[0006] Slip of the power section occurs when high pressure fluid
bypasses the interface between the rotor and the stator without
producing a resultant rotational force in the rotor. 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.
[0007] Progressive cavity pumps, also known as progressing cavity
pumps or eccentric screw pumps, are typically comprised of a
helical steel rotor that turns rotatably within a helical-shaped,
polymer-lined stator.
[0008] The rotor is typically turned by a mechanical means, such as
a motor or subassembly of a drill string. As the rotor turns, the
interface between the rotor and the stator rotates around the
centerline of the stator, advancing the cavities lengthwise along
the stator to force the contents of the cavities through the stages
of the pump.
[0009] 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.
[0010] 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.
[0011] 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.
[0012] 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.
[0013] 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.
[0014] Polymer elements of stators are typically manufactured with
elastomer compounds comprised of a nitrile-base polymer,
reinforcing materials, curatives, accelerators, and
plasticizers.
[0015] Stators are typically manufactured by an injection molding
process that introduces a relatively high viscosity, uncured
polymer compound into an annular space between a mold and the inner
wall of the stator housing. It is preferred that the polymer
element of the stator lining is formed evenly and uniformly to
avoid inconsistent thickness of the polymer that may cause
excessive flexure of the rotor and excessive stress in the
polymer.
[0016] 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.
[0017] Therefore, need exists for an improved polymer compound for
a stator and rotor assembly for a power section of a positive
displacement fluid motor or a progressive cavity pump that has a
high resistance to heat and abrasion, a low coefficient of
friction, high durability, sustains repeated stress and strain
loading without premature failure, and is resistant to chemical
interaction. Additionally, need exists for a polymer for a stator
or rotor for a power section of a positive displacement fluid motor
or a progressive cavity pump that has a reduced uncured viscosity
to allow for improved injection molding of a polymer element in a
stator housing or molding onto the surface of a rotor.
SUMMARY OF THE INVENTION
[0018] While the stator and rotor assembly and the method of
manufacturing the present invention are discussed in the context of
a positive displacement fluid motor and a progressive cavity pump,
it will be appreciated that the present invention is also
applicable to other systems that require repetitive flexure of
polymers.
[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.
[0021] The polymer host material may be polymers, including but not
limited to, elastomers, thermosets, or thermoplastics.
[0022] The polymer host material may be an elastomer, such as
nitrile, a copolymer of acrylonitrile and butadiene (NBR), or
carboxylated acrylonitrile butadiene (XNBR), or hydrogenated
acrylonitrile butadiene (HNBR), commonly referred to as highly
saturated nitrile (HSN), or carboxylated hydrogenated acrylonitrile
butadiene (XHNBR), or hydrogenated carboxylated acrylonitrile
butadiene (HXNBR).
[0023] The polymer host material may be a flurocarbon (FKM), such
as tetrafluoroethylene and propylene (FEPM), or perfluoroelastomer
(FFKM).
[0024] The polymer host material may also be polychloroprene rubber
(CR), natural rubber (NR), polyether eurethane (EU), styrene
butadiene rubber (SBR), ethylene propylene (EPR), or ethylene
propylene diene (EPDM) or similar elastomers.
[0025] The polymer host material may be a thermoplastic, such as
polyphenylene sulfide (PPS), polyetherketone-ketone (PEKK),
polyetheretherketone (PEEK), polyetherketone (PEK),
polytetrafluorethylene (PTFE) or polysulphones (PSU).
[0026] The nano structures of the nano composite material may
include nano-sized particles approximately 0.1 nanometers to
approximately 500 nanometers in the smallest dimension. Nano
structures may be from a variety of shapes, such as plates,
spheres, cylinders, tubes, fibers, three-dimensional structures,
linear molecules, molecular rings, branched molecules and
crystalline, amorphous, or symmetric shapes.
[0027] Nano particles may be from a variety of materials, such as
carbon, silica, calcium, calcium carbonate, inorganic clays, or
minerals. The nano structures may be formed from materials, such as
nano clays, carbon nano fibers, carbon nano tubes or nano
arrays.
[0028] The polymer host material and the nano structures may
interact via interfacial interactions, such as co-polymerization,
crystallization, van der Waals interactions, covalent bonds, ionic
bonds, and cross-linking interactions. The interfacial interactions
may be improved by chemical functionalization of the nano
particles.
[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.
[0032] In an alternate embodiment, the inner surface of the stator
may be a helical curve-shaped surface with a plurality of lobes
dispersed longitudinally along the inner surface of the stator, and
the rotor may be a steel helix coated with a uniform layer of
compliant polymer of sufficient thickness to hydraulically engage
the helical curve-shaped surface of the stator.
[0033] In another aspect, the present invention is directed to a
method for forming a stator assembly of a power section of a
positive displacement drill motor or a progressive cavity pump that
comprises injection molding a nano particle reinforced polymer
comprised of a polymer host material and one or more nano-sized
structures into an annular area between a mold disposed inside a
metal stator housing and the stator housing and curing the
elastomer.
[0034] In an alternate embodiment, the method comprises steps that
include coating a rotor with a nano particle reinforced polymer
layer of sufficient uniform thickness to hydraulically engage a
helical curve-shaped surface of the stator housing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] For a more complete understanding of the features and
advantages of the present invention, reference is now made to the
detailed description of the invention along with the accompanying
figures in which corresponding numerals in the different figures
refer to corresponding parts and in which:
[0036] FIG. 1 is an elevation view of a stator and rotor assembly
comprised of a stator housing, a contoured metal rotor disposed
internally in the stator housing and a helically-lobed polymer
element lining the stator housing according to an embodiment of the
present invention;
[0037] FIG. 2 is a cross section illustration of a contoured metal
rotor disposed internally in a stator housing, said housing having
an improved polymer element lining the stator housing according to
an embodiment of the present invention;
[0038] FIG. 3 is a cross section illustration of a contoured metal
rotor disposed internally in a stator housing, said rotor having an
improved polymer layer that engages the helical curve-shaped
surface of the stator housing;
[0039] FIG. 4 is a schematic illustration of a nano particle
composite polymer material comprised of a polymer host material and
interlinked nano particles according to an embodiment of the
present invention;
[0040] FIG. 5 is a schematic illustration of a nano particle
composite polymer material comprised of a polymer host material and
interlinked nano tubes or nano fibers according to an embodiment of
the present invention;
[0041] FIG. 6 is a schematic illustration of a single-wall carbon
nano tube;
[0042] FIG. 7 is a schematic illustration of a multi-wall carbon
nano tube;
[0043] FIG. 8 is a schematic illustration of a single-wall carbon
nano tube imbedded in a polymer host material and interlinked nano
particles according to an embodiment of the present invention;
[0044] FIG. 9 is a schematic illustration of a nano particle
composite polymer material comprising a polymer host material and a
nanostructure according to an embodiment of the present
invention;
[0045] FIG. 10 is a schematic illustration of a silicon-based
nanostructure according to an embodiment of the present
invention;
[0046] FIG. 11 is a schematic illustration of a silicon-based
nanostructure according to an embodiment of the present
invention;
[0047] FIG. 12 is a schematic illustration of a silicon-based
nanostructure according to an embodiment of the present
invention;
[0048] FIG. 13 is a schematic illustration of a silicon-based
nanostructure according to an embodiment of the present invention;
and
[0049] FIG. 14 is a schematic illustration of a nano particle
composite polymer material, including a polymer host material, a
plurality of nanostructures and an additive according to an
embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0050] In the following description, numerous details are set forth
to provide an understanding of the present invention. It should be
understood by those of ordinary skill in the art that the present
invention may be practiced without these details and that numerous
variations or modifications from the described embodiments may be
possible. The specific embodiments discussed herein are merely
illustrative of specific ways to make and use the invention and do
not delimit the scope of the present invention.
[0051] The present invention generally relates to a system and
method of manufacture for an improved polymer element of a stator
and rotor assembly. The system and method are useful, for example,
with a variety of applications related to a power section of a
positive displacement fluid motor or a progressive cavity pump or a
fluid pulse generating device; for example, Halliburton's Pulsonix
Deep Wave technology.
[0052] Referring generally to FIG. 1, a system 25 is illustrated
according to an embodiment of the present invention. In this
embodiment, a stator and rotor assembly 25 is comprised of a stator
20 comprising an external tubular member 21 having an internal core
of a polymer material 22 molded therein to define an elongated
annular space 23. The rotor 24 is formed of a rigid material, for
example, metal, and is disposed axially within the annular space
23.
[0053] In this embodiment, the tubular member 21 may be a metal
tube and the uncured polymer may be molded into the tubular member
by utilizing a helical-shaped mold (not shown) that is extended
through center of the tubular member 21 before the uncured polymer
22 is injected into the annular space 23 between the mold and the
inner wall of the tubular member 21. The mold is subsequently
removed from the annular space 23 after the polymer 22 is cured.
The polymer may be cured by applying heat treatment or pressure or
a combination.
[0054] Referring generally to FIG. 2, a cross section of a stator
and rotor assembly 25' is illustrated according to an embodiment of
the present invention. The rotor 24' may be machined of metal with
an elongated helical configuration. The outer surface of the rotor
24' is preferably polished and may even be coated with a
friction-reducing surface to reduce the torque necessary to
overcome friction between the polymer element 22' of the stator 20'
and the rotor 24' which are in contact with one another with an
interference fit.
[0055] In one embodiment of stator and rotor assembly 25', the
annular space 23' in the stator 20' is a two-start helical thread
which extends in the same direction as that of the thread of the
rotor 24', wherein each thread of the two-start configuration has a
pitch length double that of the rotor 24'.
[0056] Referring generally to FIG. 3 and in alternative embodiments
of the present invention, the rotor 24'' may have a plurality of
lobes 26'' of quantity N and the polymer element 22'' of the stator
20'' may have a number N+1 of threads forming the annular space
23'' of the stator 20''.
[0057] In alternative embodiments of the present invention, the
inner surface of the stator 20'' may be a helical curve-shaped
profile with a plurality of lobes 29'' dispersed longitudinally
along the inner surface of the stator 20''. In the alternate
embodiment, the rotor 24'' may be bonded to an outer layer of
compliant polymer 28'' of sufficient uniform thickness to
hydraulically engage the helical curve-shaped inner surface of the
stator 20''.
[0058] Referring again to FIG. 1, as the rotor 24 is rotated
relative to the stator 20 within the annular space 23 of the stator
20, the single-start thread of the rotor 24 progressively contacts
the two-start threads of the annular space 23 to form a series of
pockets which progress from one end of the stator and rotor
assembly 25 to the other. While rotating, the central axis of the
rotor 24 orbits about the central axis of the stator 20. One end of
the rotor 24 is provided with a connective end for receiving a tool
(not shown). The rotor 24 rotates the tool and imparts the
above-described orbital movement.
[0059] In an alternate embodiment of the present invention, the
stator and rotor assembly 25 function as a power section of a
positive displacement mud motor and the output of the rotor 24 is
affixed to a drive shaft (not shown) connected to a downhole well
tool; for example, a drill bit (not shown).
[0060] Conduits (not shown) may be attached to opposite ends of the
stator and rotor assembly 25, which conduits provide inlet and
outlet ports for the pumped fluid.
[0061] As indicated above, the diameter of the cross section of the
annular space 23 of the stator 20 is the same or less than the
diameter of the circular shape of the rotor 24, thus providing an
interference fit between the inner surface of the stator polymer 22
and the outer surface of the rotor 24. At the points of contact
between the stator 20 and the rotor 24, there may be distortion of
the polymer material 22 as the stator 20 engages with the rotor 24.
The points of engagement trace the elongated path of the rotor 24
as it rotates and contacts the polymer material 22. The annular
spaces 23 formed by the points of engagement between the rotor 24
and polymer material 22 move progressively toward an outlet end of
the stator and rotor assembly 25 as the rotor 24 rotates relative
to the stator 20. The points of engagement define a seal between
the annular spaces 23. The more effective the seal between the
rotor 24 and polymer material 22, the greater the differential
pressure that may be achieved without stalling of the stator and
rotor assembly 25; thereby producing a higher output torque.
[0062] In an alternate embodiment of the present invention, the
stator and the rotor assembly 25 comprise a progressive cavity
pump. In this embodiment, the rotor 24 is turned rotatably by a
drive source (not shown), for example, a motor, and a fluid is
pumped from stage to stage of the pump to an outlet by the
progressing annular spaces 23 of the stator and rotor assembly 25.
In this embodiment, the more effective the seal between the rotor
24 and the polymer material 22, the greater the discharge pressure
of the pump.
[0063] The elastomers of the stator and rotor assembly 25 of the
present invention are preferably formed from a polymer material
that has improved properties for substantially recovering in shape
and size after removal of a deforming force; that is, a polymer
material that exhibits physical and mechanical properties relative
to elastic memory and elastic recovery. Accordingly, elastomers of
the stator and rotor assembly 25 of the present invention are
preferably formed from a polymer material produced by a curing
method that involves compounding or mixing a base polymer with
filler additives or agents that reinforce the polymer and improve
the physical and chemical properties of the cured polymer 22.
[0064] In the various embodiments of the present invention, the
polymer material of the stator and rotor assembly 25 may be
manufactured from a polymer composite that includes a polymer host
reinforced with a plurality of nano-sized filler material.
Introduction of nano-sized filler particles to the uncured polymer
may improve the physical and chemical properties of the cured
polymer by reducing improving impact strength, improving stress
relaxation resistance, improving compression set properties,
improving durability and modulus, increasing tear strength,
reducing creep, increasing resistance to thermal and hysteresis
failure and improving resistance to chemical degradation of the
polymer.
[0065] The filler material is generally a nano-sized material in
the range from approximately 0.1 nanometers to approximately 500
nanometers, at the least dimension.
[0066] Nano particle reinforced polymers generally require smaller
amounts of filler material than traditional fillers to achieve
comparable improvements in physical and chemical properties as
compared to polymers with significantly larger particles or
non-reinforced polymers. The smaller amount of nano material
required to reinforce the elastomer has a concomitant effect of
lowering the uncured viscosity of the elastomer thus improving the
ability to form longer and thinner profiles of polymer elements of
stator and rotor assemblies.
[0067] Referring generally to FIG. 4, a polymer reinforced with
nano-sized particles is illustrated 50. In this embodiment, a
polymer composite 50 comprises a polymer host material, formed of
polymer chains 52, and reinforced with a plurality of nano-sized
particles 54 functionalized with chemical agents that serve as
cross-linking agents.
[0068] The polymer host material may be elastomers, thermosets or
thermoplastics.
[0069] The polymer host material may be an elastomer, such as
nitrile, a copolymer of acrylonitrile and butadiene (NBR), or
carboxylated acrylonitrile butadiene (XNBR), or hydrogenated
acrylonitrile butadiene (HNBR), commonly referred to as
highly-saturated nitrile (HSN), or carboxylated hydrogenated
acrylonitrile butadiene (XHNBR), or hydrogenated carboxylated
acrylonitrile butadiene (HXNBR).
[0070] In an alternative embodiment of the present invention, the
polymer host material may be a flurocarbon (FKM), such as
tetrafluoroethylene and propylene (FEPM), or perfluoroelastomer
(FFKM).
[0071] In an alternative embodiment of the present invention, the
polymer host material may also be polychloroprene rubber (CR),
natural rubber (NR), polyether eurethane (EU), styrene butadiene
rubber (SBR); ethylene propylene (EPR), ethylene propylene diene
(EPDM) or similar elastomers.
[0072] In an alternative embodiment of the present invention, the
polymer host material may be a thermoplastic (TPE), such as
polyphenylene sulfide (PPS), polyetherketone-ketone (PEKK),
polyetheretherketone (PEEK), polyetherketone (PEK),
polytetrafluorethylene (PTFE), or polysulphone (PSU).
[0073] Nano structures may include shapes, such as plates, spheres,
cylinders, tubes, fibers, three-dimensional structures, linear
molecules, molecular rings, branched molecules and crystalline,
amorphous, and symmetric shapes.
[0074] Nano particles may be from a variety of materials, such as
carbon, silica, metals, graphite, diamond, ceramics, metal oxides,
other oxides, calcium, calcium carbonate, inorganic clays,
minerals, and polymer materials. For example, the nano structures
may be formed from silicon material, such as polysilane resins,
polycarbosilane resins (PCS), polysilsesquioxane resins (POS) and
polyhedral oligomeric silsesquioxane resins (POSS).
[0075] Nano clay may be derived, for example, from montmorillonite,
bentonite, hectorite, attapulgite, kaolin, mica and illite.
[0076] Nano tubes can be formed from a variety of materials, for
example, carbon. Carbon nano tubes exhibit desirable combinations
of mechanical, thermal and electrical properties for applications
defined by the present invention. Nano fibers may be derived, for
example, from graphite, carbon, glass, cellulose substrate and
polymer materials. Carbon nano tubes are generally in the range
from approximately 0.5 nanometers to approximately 100 nanometers,
at the least dimension. Carbon nano fibers are generally in the
range from approximately 10 nanometers to approximately 500
nanometers, at the least dimension. Nano clays are generally in the
range from approximately 0.1 nanometers to approximately 100
nanometers, at the least dimension.
[0077] Referring generally to FIG. 5, in an alternate embodiment,
the polymer composite 55 comprises a polymer host material, formed
of polymer chains 52 and reinforced with nano-sized particles 56
comprised of nano tubes or nano fibers. As illustrated in FIG. 5,
nano tubes can be formed as single-wall nano tubes. As illustrated
in FIG. 7, nano tubes also can be formed as multi-wall nano tubes.
As illustrated in FIG. 8, nano tubes can be formed as arrays of
nano tubes.
[0078] Nano particles may include metal oxides of zinc, iron,
titanium, magnesium, silicon, aluminum, cerium, zirconium and
equivalents thereof, as well as mixed metal compounds, such as
indium-tin and equivalents thereof.
[0079] Referring generally to FIG. 9, in an alternate embodiment,
nano structure 160 may be formed from polysilane resins (PS), as
depicted in FIG. 10, polycarbosilane resins (PCS), as depicted in
FIG. 11, polysilsesquioxane resins (PSS), as depicted in FIG. 12,
or polyhedral oligomeric silsesquioxane resins (POSS), as depicted
in FIG. 13, as well as monomers, polymers and copolymers thereof.
In the formulas presented in FIGS. 10, 11, 12 and 13, R represents
a hydrogen or an alkane, alkenyl or alkynl hydrocarbons, cyclic or
linear, with 128 carbon atoms, substituted hydrocarbons R--X,
aromatics where X represents halogen, phosphorus or
nitrogen-containing groups. The incorporation of halogen or other
inorganic groups, such as phosphates and amines, directly onto
these nano particles may afford additional improvements to the
mechanical properties of the material. For example, the
incorporation of halogen group may afford additional heat
resistance to the material. These nano structures may also include
termination points, such as chain ends that contain reactive or
nonreactive functionalities, such as silanols, esters, alcohols,
amines or R groups.
[0080] Referring generally to FIG. 9, a nano composite material 150
forming an elastomer element of a stator and rotor assembly 25 of
the present invention is depicted. Nano composite material 150 is
comprised of a polymer host material 152 that may include a
plurality of polymers 154, 156, 158 and a plurality of nano
structures. 160. The polymer host material 152 exhibits
microporocity as represented by a plurality of regions of free
volume 162. The nano particles 160 are positioned within free
volume region 162.
[0081] The polymer host material 152 and the nano structures 160
may interact via interfacial interactions, such as
co-polymerization, crystallization, van der Waals interactions,
covalent bonds, ionic bonds, and cross-linking interactions between
nano structure 160 and polymers 154, 156, 158 to improve the
physical and chemical characteristics of the polymer thereby
resulting in an extended life for the stator and rotor assembly 25
of the present invention.
[0082] In an alternative embodiment, the nano particle structures
may be functionalized to enhance the effective surface area and
improve the availability of potential chemical reactions or
catalysis sites for chemical functional groups on the nano
structure. Surface functionalization introduces chemical functional
groups to a surface, such as the surface of the polymer, thereby
providing a surface layer with increased surface area and
containing uniform pores with a high effective surface area, thus
increasing the number of potential chemical reactions or catalysis
sites on the nano particle structure.
[0083] While the present invention has been illustrated and
described with reference to particular apparatus and methods of
use, it is apparent that various changes can be made thereto within
the scope of the present invention as defined by the appended
claims.
* * * * *