U.S. patent application number 10/936279 was filed with the patent office on 2006-03-09 for shape memory alloy for erosion control of downhole tools.
Invention is credited to Pete C. Dagenais, Michael L. Fripp, Syed Hamid, Robert Ken Michael, Roger L. Schultz, Neal G. Skinner.
Application Number | 20060048936 10/936279 |
Document ID | / |
Family ID | 35385493 |
Filed Date | 2006-03-09 |
United States Patent
Application |
20060048936 |
Kind Code |
A1 |
Fripp; Michael L. ; et
al. |
March 9, 2006 |
Shape memory alloy for erosion control of downhole tools
Abstract
A downhole fluid flow control device (188) and method for
minimizing erosion are disclosed. The downhole fluid flow control
device (188) includes a downhole surface (190) subjectable to an
erosive stress (196, 198) which may be a moving fluid or an erosive
agent, for example. A shape memory alloy (192) is integrated with
the downhole surface (190) in order to provide erosion resistance
by reversibly transforming from an austenitic phase (194) to a
martensitic phase (200) in response to the application of the
erosive stress (196, 198). Further, the shape memory alloy (192)
reversibly transforms from the martensitic phase (200) to the
austenitic phase (192) in response to the presence of sufficient
heat.
Inventors: |
Fripp; Michael L.;
(Carrollton, TX) ; Hamid; Syed; (Dallas, TX)
; Schultz; Roger L.; (Aubrey, TX) ; Dagenais; Pete
C.; (The Colony, TX) ; Michael; Robert Ken;
(Frisco, TX) ; Skinner; Neal G.; (Lewisville,
TX) |
Correspondence
Address: |
LAWRENCE R. YOUST;DANAMRAJ & YOUST, P.C.
5910 NORTH CENTRAL EXPRESSWAY
SUITE 1450
DALLAS
TX
75206
US
|
Family ID: |
35385493 |
Appl. No.: |
10/936279 |
Filed: |
September 7, 2004 |
Current U.S.
Class: |
166/244.1 ;
166/316 |
Current CPC
Class: |
E21B 34/066 20130101;
E21B 43/12 20130101 |
Class at
Publication: |
166/244.1 ;
166/316 |
International
Class: |
E21B 34/00 20060101
E21B034/00 |
Claims
1. A downhole fluid flow control device comprising: a downhole
surface subjectable to an erosive stress; and a shape memory alloy
integrated with the downhole surface, the shape memory material
operable to provide erosion resistance.
2. The downhole fluid flow control device as recited in claim 1
wherein the shape memory alloy is operable to reversibly transform
between austenitic and martensitic phases responsive to the erosive
stress and temperature.
3. The downhole fluid flow control device as recited in claim 1
wherein the shape memory material reversibly transforms from an
austenitic phase to a martensitic phase in response to application
of the erosive stress.
4. The downhole fluid flow control device as recited in claim 1
wherein the shape memory material reversibly phase transforms
responsive to erosive stress and temperature.
5. The downhole fluid flow control device as recited in claim 1
wherein the shape memory material reversibly transforms from a
martensitic phase to an austenitic phase in response to application
of a temperature .E-backward. A.sup.0f.
6. The downhole fluid flow control device as recited in claim 1
wherein the shape memory material is at a temperature .E-backward.
A.sup.0f and reversibly transforms from an austenitic phase to a
martensitic phase in response to application of the erosive
stress.
7. The downhole fluid flow control device as recited in claim 6
wherein the shape memory material reversibly transforms from the
martensitic phase to the austenitic phase in response to removal of
the erosive stress.
8. The downhole fluid flow control device as recited in claim 1
wherein the shape memory material comprises an alloy selected from
the group consisting of titanium nickel (TiNi) alloys, titanium
carbon-Titanium nickel (TiC--TiNi) composite alloys, copper zinc
(CuZn) alloys, copper zinc aluminum (CuZnAl) alloys, copper zinc
gallium (CuZnGa) alloys, copper zinc tin (CuZnSn) alloys, copper
zinc silicon (CuZnSi) alloys, iron platinum (FePt) alloys and
tribological engineering materials.
9. The downhole fluid flow control device as recited in claim 1
wherein the shape memory material has pseudoelasticity recoverable
strain between approximately 1.5% and approximately 8.5%.
10. The downhole fluid flow control device as recited in claim 1
wherein the shape memory material has resistance to chemical
corrosion equivalent to a 304-series stainless-steel.
11. The downhole fluid flow control device as recited in claim 1
wherein the downhole surface and shape memory material form a
portion of an assembly selected from the group consisting of
back-pressure valves, ball valves, check valves, circulation
valves, safety valves, equalizing valves, flapper valves, foot
valves, frac valves, gas-lift valves, gate valves, isolation
valves, operating gas-lift valves, orifice valves, poppet valves,
reverse-circulating valves, sliding sleeves, standing valves,
subsurface safety valves, traveling valves, tubing-retrievable
safety valves and wireline-retrievable safety valves.
12. The downhole fluid flow control device as recited in claim 1
wherein the erosive stress comprises a moving fluid.
13. The downhole fluid flow control device as recited in claim 1
wherein the erosive stress comprises an erosive agent.
14. The downhole fluid flow control device as recited in claim 1
wherein the erosive stress comprises friction.
15. A downhole tool comprising: a downhole component having a
surface subjectable to erosion; and a shape memory alloy integrated
with the surface, the shape memory material operable to resist
erosion by reversibly transforming between austenitic and
martensitic phases.
16. The downhole tool as recited in claim 15 wherein the shape
memory material reversibly transforms from an austenitic phase to a
martensitic phase in response to application of an erosive
stress.
17. The downhole tool as recited in claim 15 wherein the shape
memory material reversibly transforms from a martensitic phase to
an austenitic phase in response to a temperature .E-backward.
A.sup.0f.
18. The downhole tool as recited in claim 15 wherein the shape
memory material is at a temperature .E-backward. A.sup.0f and
reversibly transforms from an austenitic phase to a martensitic
phase in response to application of an erosive stress.
19. The downhole tool as recited in claim 18 wherein the shape
memory material reversible transforms from the martensitic phase to
the austenitic phase in response to removal of the erosive
stress.
20. The downhole tool as recited in claim 15 wherein the shape
memory material comprises an alloy selected from the group
consisting of titanium nickel (TiNi) alloys, titanium
carbon-titanium nickel (TiC--TiNi) composite alloys, copper zinc
(CuZn) alloys, copper zinc aluminum (CuznAl) alloys, copper zinc
gallium (CuZnGa) alloys, copper zinc tin (CuZnSn) alloys, copper
zinc silicon (CuZnSi) alloys, iron platinum (FePt) alloys and
tribological engineering materials.
21. The downhole tool as recited in claim 15 wherein the shape
memory material has pseudoelasticity recoverable strain between
approximately 1.5% and approximately 8.5%.
22. The downhole tool as recited in claim 15 wherein the shape
memory material has resistance to chemical corrosion equivalent to
a 304-series stainless-steel.
23. The downhole tool as recited in claim 15 wherein a moving fluid
creates an erosive stress.
24. The downhole tool as recited in claim 15 wherein an erosive
agent creates an erosive stress.
25. The downhole tool as recited in claim 15 wherein friction
creates an erosive stress.
26. The downhole tool as recited in claim 15 wherein the downhole
component is selected from the group consisting of crossovers,
blast joints, sand screens, valves, nozzles, chokes, wear surfaces
of vanes, pump pistons, turbine blades, flow straighteners, flow
mixers, internal mandrels, barrel slips, flow diverters, seal
assemblies, shifting sleeves, collets, snap rings, c-clamps on ball
valves, landing nipples, poppets, rotors, bearings, races,
slickline wires, venturis and tubulars.
27. An oilfield tool comprising: a component having a surface
subjectable to erosion; and a shape memory alloy integrated with
the surface, the shape memory material operable to resist erosion
by reversibly transforming between austenitic and martensitic
phases.
28. The oilfield tool as recited in claim 27 wherein the shape
memory material reversibly transforms from an austenitic phase to a
martensitic phase in response to application of an erosive
stress.
29. The oilfield tool as recited in claim 27 wherein the shape
memory material reversibly transforms from a martensitic phase to
an austenitic phase in response to a temperature .E-backward.
A.sup.0f.
30. The oilfield tool as recited in claim 27 wherein the shape
memory material is at a temperature .E-backward. A.sup.0f and
reversibly transforms from an austenitic phase to a martensitic
phase in response to application of an erosive stress.
31. The oilfield tool as recited in claim 30 wherein the shape
memory material reversible transforms from the martensitic phase to
the austenitic phase in response to removal of the erosive
stress.
32. The oilfield tool as recited in claim 27 wherein the shape
memory material comprises an alloy selected from the group
consisting of titanium nickel (TiNi) alloys, titanium
carbon-titanium nickel (TiC--TiNi) composite alloys, copper zinc
(CuZn) alloys, copper zinc aluminum (CuZnAl) alloys, copper zinc
gallium (CuZnGa) alloys, copper zinc tin (CuZnSn) alloys, copper
zinc silicon (CuZnSi) alloys, iron platinum (FePt) alloys and
tribological engineering materials.
33. The oilfield tool as recited in claim 27 wherein the shape
memory material has pseudoelasticity recoverable strain between
approximately 1.5% and approximately 8.5%.
34. The oilfield tool as recited in claim 27 wherein the shape
memory material has resistance to chemical corrosion equivalent to
a 304-series stainless-steel.
35. The oilfield tool as recited in claim 27 wherein a moving fluid
creates an erosive stress.
36. The oilfield tool as recited in claim 27 wherein an erosive
agent creates an erosive stress.
37. The oilfield tool as recited in claim 27 wherein friction
creates an erosive stress.
38. The oilfield tool as recited in claim 27 wherein the component
is selected from the group consisting of casing valves, master
valves, stabbing valves, swab valves, wing valves, wellhead
isolation tools, pump jack components, flow lines and vessels.
39. A method for controlling erosion in a component comprising the
steps of: disposing the component downhole, the component including
a shape memory material integrated with a surface of the component;
and exposing the shape memory material to a downhole stimulus that
transforms at least a portion of the shape memory material from a
first phase to a second phase.
40. The method as recited in claim 39 wherein the step of exposing
the shape memory material to the downhole stimuli further comprises
the step of exposing the shape memory material to particulate
impact that transforms the at least a portion of the shape memory
material from an austenitic phase to a martensitic phase.
41. The method as recited in claim 39 wherein the step of exposing
the shape memory material to the downhole stimuli further comprises
the step of exposing the shape memory material to a moving fluid
that transforms the at least a portion of the shape memory material
from an austenitic phase to a martensitic phase.
42. The method as recited in claim 39 wherein the step of exposing
the shape memory material to the downhole stimuli further comprises
the step of exposing the shape memory material to an erosive stress
that transforms the at least a portion of the shape memory material
from an austenitic phase to a martensitic phase.
43. The method as recited in claim 39 wherein the step of exposing
the shape memory material to the downhole stimuli further comprises
the step of exposing the shape memory material to friction that
transforms the at least a portion of the shape memory material from
an austenitic phase to a martensitic phase.
44. The method as recited in claim 39 wherein the step of exposing
the shape memory material to the downhole stimuli further comprises
the step of exposing the shape memory material to temperature
.E-backward. A.sup.0f that transforms the at least a portion of the
shape memory material from a martensitic phase to an austenitic
phase.
45. The method as recited in claim 39 wherein the step of exposing
the shape memory material to the downhole stimuli further comprises
the step of exposing the shape memory material to a temperature #
M.sup.0f that transforms the at least a portion of the shape memory
material from an austenitic phase to a martensitic phase.
46. The method as recited in claim 39 wherein the step of exposing
the shape memory material to a downhole stimuli further comprises
the step of exposing the shape memory material to a combination of
temperature and stress that transforms the at least a portion of
the shape memory material from the first phase to the second
phase.
47. The method as recited in claim 39 further comprising the step
of exposing the shape memory material to another downhole stimuli
that transforms the at least a portion of the shape memory material
from the second phase to the first phase.
48. The method as recited in claim 39 further comprising the step
of exposing the shape memory material to temperature .E-backward.
A.sup.0f that transforms the at least a portion of the shape memory
material from the second phase to the first phase.
49. The method as recited in claim 39 further comprising the step
of removing the downhole stimuli to transform the at least a
portion of the shape memory material from the second phase to the
first phase.
50. The method as recited in claim 39 further comprising the step
of selecting the shape memory material from the group consisting of
titanium nickel (TiNi) alloys, titanium carbon-titanium nickel
(TiC--TiNi) composite alloys, copper zinc (Cuzn) alloys, copper
zinc aluminum (CuznAl) alloys, copper zinc gallium (CuZnGa) alloys,
copper zinc tin (CuZnSn) alloys, copper zinc silicon (CuznSi)
alloys, iron platinum (FePt) alloys and tribological engineering
materials.
51. The method as recited in claim 39 wherein the step of exposing
the shape memory material to a downhole stimuli further comprises
the step of displaying pseudoelasticity recoverable strain between
approximately 1.5% and approximately 8.5%.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates, in general, to preventing
erosion of downhole tools positioned within a wellbore that
traverses a subterranean hydrocarbon bearing formation and, in
particular, to downhole tools having a shape memory alloy
integrated therein to provide erosion resistance.
BACKGROUND OF THE INVENTION
[0002] Without limiting the scope of the invention, the background
will describe surface controlled, subsurface safety valves, as an
example.
[0003] Surface controlled, subsurface safety valves are commonly
used to shut in oil and gas wells in the event of a failure or
hazardous condition at the well surface. Such safety valves are
typically fitted into the production tubing and operate to block
the flow of formation fluid upwardly therethrough. The subsurface
safety valve provides automatic shutoff of production flow in
response to a variety of out of range safety conditions that can be
sensed or indicated at the surface. For example, the safety
conditions include a fire on the platform, a high or low flow line
temperature or pressure condition or operator override.
[0004] During production, the subsurface safety valve is typically
held open by the application of hydraulic fluid pressure conducted
to the subsurface safety valve through an auxiliary control conduit
which extends along the tubing string within the annulus between
the tubing and the well casing. Flapper type subsurface safety
valves utilize a closure plate which is actuated by longitudinal
movement of a hydraulically actuated, tubular piston. The flapper
valve closure plate is maintained in the valve open position by an
operator tube which is extended by the application of hydraulic
pressure onto the piston. A pump at the surface pressurizes a
reservoir which delivers regulated hydraulic control pressure
through the control conduit. Hydraulic fluid is pumped into a
variable volume pressure chamber and acts against the piston. When,
for example, the production fluid pressure rises above or falls
below a preset level, the control pressure is relieved such that
the piston and operator tube are retracted to the valve closed
position by a return spring. The flapper plate is then rotated to
the valve closed position by a torsion spring or tension member in
conjunction with fluid forces.
[0005] In conventional subsurface safety valves of the type
utilizing an upwardly closing flapper plate, the flapper plate is
seated against an annular sealing face, either in metal-to-metal
contact or metal against an annular elastomeric seal. In one
design, the valve seat and the upwardly closing flapper plate each
having a sealing surface with a matched spherical radius of
curvature. That is, the valve seat is a concave spherical segment
and the sealing surface of the flapper plate is a convex spherical
segment. In this arrangement, the spherical radius of curvature of
the concave valve seat spherical segment is matched with the
spherical radius of curvature of the convex spherical segment which
defines the sealing surface on the flapper plate. The matching
spherical surfaces are lapped together to provide a metal-to-metal
seal along the interface between the nested convex and concave
sealing surfaces.
[0006] It has been found, however, that even when using spherical
sealing surfaces leakage may occur. Specifically, erosion of the
concave valve seat spherical segment caused by an erosive stress
may result in the loss of the ability to create a seal between
sealing surfces. These erosive stresses include moving fluids and
erosive agents such as particulate matter. Therefore, a need has
arisen for an erosion resistant material that can be used for the
sealing surfaces of a subsurface safety valve. Additionally, a need
has arisen for such an erosion resistant material that can
withstand erosive stresses such as moving fluids and erosive agents
without exhibiting erosive wear.
SUMMARY OF THE INVENTION
[0007] The present invention disclosed herein comprises a downhole
fluid flow control device and method for minimizing erosion that
utilize an erosive resistant material for sealing surfaces. In
particular, the erosion resistant material comprises a shape memory
alloy that is capable of withstanding erosive stresses such as
moving fluids and erosive agents without exhibiting excessive
erosive wear.
[0008] In one aspect, the downhole fluid flow control device
includes a downhole surface subjectable to an erosive stress which
may be a moving fluid or an erosive agent, for example. A shape
memory alloy is integrated with the downhole surface in order to
provide erosion resistance by reversibly transforming between an
austenitic phase and a martensitic phase in response to the
application of the erosive stress. Further, the shape memory alloy
reversibly transforms from the martensitic phase to the austenitic
phase in response to the application of heat.
[0009] In one embodiment, the shape memory alloy reversibly
transforms from a martensitic phase to an austenitic phase in
response to application of a temperature .E-backward. A.sup.of.
Alternatively, the shape memory alloy may be at a temperature
.E-backward. A.sup.of and reversibly transform from an austenitic
phase to a martensitic phase in response to application of the
erosive stress. Thereafter, the shape memory alloy may reversibly
transform from the martensitic phase to the austenitic phase in
response to removal of the erosive stress.
[0010] In one embodiment, the shape memory alloy may include
titanium nickel (TiNi) alloys, titanium carbon-titanium nickel
(TiC--TiNi) composite alloys, copper zinc (CuZn) alloys, copper
zinc aluminum (CuZnAl) alloys, copper zinc gallium (CuZnGa) alloys,
copper zinc tin (CuZnSn) alloys, copper zinc silicon (CuZnSi)
alloys, iron platinum (FePt) alloys, tribological engineering
materials or the like. The shape memory alloy may have
pseudoelastic recoverable strain between approximately 1.5% and
approximately 8.5% and resistance to chemical corrosion equivalent
to a 304-series stainless-steel.
[0011] The downhole surface including the shape memory alloy may
form a portion of an assembly such as a back-pressure valve, a ball
valve, a check valve, a circulation valve, a safety valve, an
equalizing valve, a flapper valve, a foot valve, a frac valve, a
gas-lift valve, gate valve, an isolation valve, an operating
gas-lift valve, an orifice valve, a poppet valve, a
reverse-circulating valve, a sliding sleeve, a standing valve, a
subsurface safety valve, a traveling valve, a tubing-retrievable
safety valve, wireline-retrievable safety valve or the like.
[0012] In a further aspect, the present invention is directed to a
downhole tool that includes a downhole component having a surface
subjectable to erosion. A shape memory alloy is integrated with the
surface in order to resist erosion by reversibly transforming
between austenitic and martensitic phases.
[0013] In one embodiment, the downhole component may be a
crossover, a blast joint, a sand screen, a valve, a nozzle, a
choke, a wear surface of a vane, a pump piston, a turbine blade, a
flow straightener, a flow mixer, an internal mandrel, a barrel
slip, a flow diverter, a seal assembly, a shifting sleeve, a
collet, a snap ring, a c-clamp on a ball valve, a landing nipple, a
poppet, a rotor, a bearing, a race, a slickline wire, a tubular, a
venturi or the like.
[0014] In another aspect, the present invention is directed to an
oilfield tool that includes a component having a surface
subjectable to erosion. A shape memory alloy is integrated with the
surface to provide resistance to erosion by reversibly transforming
between austenitic and martensitic phases.
[0015] In one embodiment, the oilfield tool may be a casing valve,
a master valve, a stabbing valve, a swab valve, a wing valve, a
wellhead isolation tool, a pump jack component, a flow line, a
vessel or the like.
[0016] In a further aspect, the present invention is directed to a
method for minimizing erosion in a component. The method includes
the steps of disposing the component, which includes a shape memory
alloy integrated with a surface of the component, and exposing the
shape memory alloy to a downhole stimuli that transforms at least a
portion of the shape memory alloy from a first phase to a second
phase. The first phase may be an austenitic phase or a martensitic
phase and the second phase may be a martensitic phase or austenitic
phase, respectively.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] 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:
[0018] FIG. 1 is a schematic illustration of an offshore oil and
gas platform performing completion operations wherein tools having
a shape memory alloy of the present invention are advantageously
deployed;
[0019] FIG. 2 is a schematic illustration of an offshore oil and
gas platform performing production operations wherein tools having
a shape memory alloy of the present invention are advantageously
deployed;
[0020] FIG. 3A-3B are half sectional views of a subsurface safety
valve in the open position utilizing a shape memory alloy of the
present invention at its sealing surface;
[0021] FIG. 4 is a cross sectional view of a flapper closure plate
and seat in the valve closed position utilizing a shape memory
alloy of the present invention at its sealing surface;
[0022] FIG. 5 is a stress-temperature phase diagram illustrating
phase transitions of a shape memory alloy of the present
invention;
[0023] FIG. 6 is a schematic illustration of a section of a tool
having a shape memory alloy of the present invention integrated
into a wear surface that is being subjected to an erosive stress
and returning to its initial phase upon removal of the erosive
stress;
[0024] FIG. 7 is a schematic illustration of a section of a tool
having a shape memory alloy of the present invention integrated
into a wear surface that is being subjected to an erosive stress
and returning to its initial phase upon application of heat;
and
[0025] FIG. 8 is a schematic illustration of a section of a tool
having a shape memory alloy of the present invention integrated
into a wear surface that is being subjected to an erosive stress
following the application of heat.
DETAILED DESCRIPTION OF THE INVENTION
[0026] While the making and using of various embodiments of the
present invention are discussed in detail below, it should be
appreciated that the present invention provides many applicable
inventive concepts which can be embodied in a wide variety of
specific contexts. 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.
[0027] Referring initially to FIG. 1, an offshore oil and gas
platform performing completion operations is schematically
illustrated and generally designated 10. A semi-submersible
platform 12 is centered over a submerged oil and gas formation 14
located below sea floor 16. A subsea conduit 18 extends from deck
20 of platform 12 to wellhead installation 22 including blowout
preventers 24. Platform 12 has a hoisting apparatus 26 and a
derrick 28 for raising and lowering pipe strings such as completion
string 30.
[0028] A wellbore 32 extends through the various earth strata
including formation 14. A casing 34 is cemented within wellbore 32
by cement 36. Casing 34 has been perforated at formation 14 to
create perforations 38 using perforating guns 40 which have been
released into the rat hole of wellbore 32. Thereafter, completion
string 30 has been lowered to locate a sand control screen assembly
44 proximate to formation 14 such that a pair of seal assemblies 46
can isolate production from formation 14. Uphole of sand control
screen assembly 44 is a cross-over 42 that allows for a treatment
operation within the production interval at formation 14 such as a
gravel pack, fracture stimulation, frac pack or the like. Uphole of
cross-over 42 is a fluid loss control valve 48 that prevents the
loss of fluid from within completion string 30 to formation 14
during completion operations to other formations (not pictured)
uphole of formation 14.
[0029] Also depicted within completion string 30 is a tubing test
valve 50 that allows for the periodic pressure testing of
completion string 30 during installation thereof. Completion string
30 also includes a plurality of landing nipples, such as landing
nipple 52, which is used to receive, for example, wireline set
tools such as permanent and temporary bridge plugs as well as other
types of flow control devices. A sliding side door valve 54 is also
depicted within completion string 30. Sliding side door valve 54
may be used to selectively permit and prevent fluid communication
between the interior of completion string 30 and the wellbore
annulus. Completion string 30 includes one or more subsurface
safety valves, such as safety valve 56, that prevent out of control
well conditions from traveling to the surface.
[0030] Many of these completion tools, as well as numerous other
downhole tools such as drilling tools and production tools, may
utilize downhole components having shape memory materials, such as
shape memory alloys, phase changing ceramics and phase changing
polymers, for example, integrated at wear surfaces. For purposes of
explanation and not by way of limitation, however, the shape memory
material will be presented as a shape memory alloy. As an example,
crossover 42 is subjected to significant volumes of high velocity
slurry during treatment operations which commonly result in erosive
wear. Utilizing a shape memory alloy of the present invention for
these wear surfaces, however, minimizes or prevents such erosive
wear. Likewise, the other components through which the slurry is
pumped are also subjected to the erosive stress. Accordingly, fluid
loss control valve 48, tubing test valve 50, sliding side door
valve 54, subsurface safety valve 56 as well as numerous other
valving and flow control devices may utilize shape memory alloy
components to minimize or prevent erosive wear, whether the erosive
wear is caused by an erosive agent, such as particulars, or
friction between components, for example. By way of example, these
other devices may include blast joints, sand screens, nozzles,
chokes, wear surfaces of vanes, pump pistons, turbine blades, flow
straighteners, flow mixers, internal mandrels, barrel slips, flow
diverters, shifting sleeves, collets, snap rings, c-clamps on ball
valves, landing nipples, poppets, rotors, bearings (e.g., bearing
surfaces in journal bearings and thrust bearings), races, slickline
wires, tubulars or venturis. As will be explained in further detail
hereinbelow, the shape memory alloy components of the downhole
tools resist erosion by reversibly transforming from an austenitic
phase to a martensitic phase in response to the application of the
erosive stress. Rather than wear, shape memory alloy components
absorb the stress erosion by reversibly transforming or reversibly
transitioning phase.
[0031] Referring next to FIG. 2, offshore oil and gas platform 10
is depicted during production operations. Disposed within casing 34
and extending from wellhead 60 is a production tubing 40. During
production, formation fluids enter wellbore 32 through perforations
38 of casing 34 and travel into production tubing string 40 through
sand control screen assembly 44 to wellhead 60 that is installed on
deck 20. Wellhead 60 includes numerous valves such as lower master
valve 61 and upper master valve 63 which provide redundant surface
isolation. Additionally, wellhead 60 includes a wing valve 65 and
swab valve 67. A flowline 69 connects wellhead 60 to vessel 71
wherein production fluid brought up from formation 14 may be
processed. Many of surface production tools may utilize the shape
memory alloys of the present invention. For example, in addition to
the valves described hereinabove, flowline 69 and vessel 71 may
utilize the shape memory alloy of the present invention at wear
surfaces such as elbows or other transition regions. Other oilfield
equipment that may utilize the shape memory alloys include casing
valves, stabbing valves and pump jack components, for example. In
addition, various downhole production tools may also benefit from
the shape memory alloy of the present invention such as downhole
choke 73, downhole turbine 75, gas lift valve 77, landing nipple
79, subsurface safety valve 56 and the like. Further, although
completion and production operations have been depicted in FIGS. 1
and 2, it should be appreciated that the shape memory alloy of the
present invention may be utilized with components of drilling
operations as well.
[0032] Referring now to FIGS. 3A and 3B, subsurface safety valve 56
is illustrated in further detail. Safety valve 56 has a relatively
larger production bore and is, therefore, intended for use in high
flow rate wells. Safety valve 56 is connected directly in series
with production tubing 40. Control conduit 62 provides hydraulic
control pressure to longitudinal bore 64 formed in the sidewall of
the top connector sub 66. Pressurized hydraulic fluid is delivered
through the longitudinal bore 64 into an annular chamber 68 defined
by a counterbore 70 which is in communication with an annular
undercut 72 formed in the sidewall of the top connector sub 66. An
inner housing mandrel 74 is slidably coupled and sealed to the top
connector sub 66 by a slip union 76 and seal 78, with the undercut
72 defining an annulus between inner mandrel 74 and the sidewall of
top connector sub 66.
[0033] A piston 80 is received in slidable, sealed engagement
against the internal bore of inner mandrel 74. The undercut annulus
72 opens into a piston chamber 82 in the annulus between the
internal bore of a connector sub 86 and the external surface of
piston 80. The external radius of an upper sidewall piston section
84 is machined and reduced to define a radial clearance between
piston 80 and connector sub 86. An annular sloping surface 88 of
piston 80 is acted against by the pressurized hydraulic fluid
delivered through control conduit 62. In FIGS. 3A-3B, piston 80 and
operator tube 94 are fully extended with the lower shoulder of
operator tube 94 engaging an annular face of bottom subconnector
106. In this valve open position, a return spring 96 is fully
compressed.
[0034] In the illustrated embodiment, a flapper plate 98 is
pivotally mounted onto a hinge sub 100 which is threadably
connected to the lower end of spring housing 102. A valve seat 104
is confined within a counterbore formed on hinge sub 100. The lower
end of safety valve 56 is connected to production tubing 40 by a
bottom sub connector 106. The bottom sub connector 106 has a
counterbore 108 which defines a valve chamber 110. Thus, the bottom
sub connector 106 forms a part of the valve housing enclosure.
Flapper plate 98 pivots about pivot pin 112 and is biased to the
valve closed position by spring 114. In the valve open position as
shown in FIGS. 3A-3B, the spring bias force is overcome and flapper
plate 98 is retained in the valve open position by operator tube 94
to permit formation fluid flow up through tubing 40.
[0035] During operation, when an out of range condition occurs and
subsurface safety valve 56 must be operated from the valve open
position to the valve closed position, hydraulic pressure is
released from conduit 62 such that return spring 96 acts on the
lower end of piston 80 which retracts operator tube 94
longitudinally through valve chamber 110. Flapper closure plate 98
will then rotate through chamber 110 to effectuate the valve
closure. Further, it is necessary to have a complete seal between
flapper closure plate 98 and valve seat 104, which is subjected to
considerable erosive stress in the form of upward moving fluids
having particulate matter. Valve seat 104 includes a sealing
surface 116 having integrated therewith a shape memory alloy of the
present invention in order to resist erosion by absorbing the
erosive stresses and reversibly transforming phases.
[0036] Referring next to FIG. 4, therein is depicted the sealing
elements of a valve that is generally designated 120. Valve 120 has
valve closure member shown as a flapper closure plate 122, which
has a convex flapper closure plate sealing surface 124.
Additionally, valve 120 includes a valve seat 126 which has concave
valve seat sealing surface 128. It should be appreciated that
concave sealing surface 128 of valve seat 126 has a radius of
curvature that is substantially equal to that of convex flapper
closure plate sealing surface 124. As previously discussed, valve
seat 126 includes a shape memory alloy layer 130 in order to resist
erosion and maintain the radius of curvature necessary to create an
effective seal with flapper closure plate sealing surface 124.
[0037] While a particular type of flow control device has been
described with respect to FIG. 4, it should be appreciated that the
shape memory alloys of the present invention may be used with other
types of valves. For example, the shape memory alloys of the
present invention may be utilized with back-pressure valves, ball
valves, check valves, circulation valves, equalizing valves, foot
valves, frac valves, gas-lift valves, gate valves, isolation
valves, orifice valves, poppet valves, reverse-circulating valves,
sliding sleeves, standing valves, traveling valves,
tubing-retrievable safety valves and wireline-retrievable safety
valves, for example. Use of the shape memory alloys of the present
invention as the wear surfaces of any of these flow control devices
will provide for shape memory effect and superelastic responses to
impingement of sand or other particulate matter, thus providing
increased wear-resistance.
[0038] Referring now to FIG. 5, therein is depicted a
stress-temperature phase diagram 150 illustrating phase transitions
of the shape memory alloy of the present invention. The x-axis is
temperature (T) and the y-axis is stress (.sigma.). In general,
shape memory alloys are metallic alloys that exist in two phases
and display both thermal and mechanical memory. By way of example,
a titanium nickel (TiNi) shape memory alloy is represented in each
of the crystal lattice structure phases. It should be appreciated
that other shape memory alloys are within the teachings of the
present invention. For example, the shape memory alloy may include
titanium carbon-titanium nickel (TiC--TiNi) composite alloys,
copper zinc (CuZn) alloys, copper zinc aluminum (CuZnAl) alloys,
copper zinc gallium (CuZnGa) alloys, copper zinc tin (CuZnSn)
alloys, copper zinc silicon (CuZnSi) alloys, iron platinum (FePt)
alloys and the like. Additionally, the shape memory may include
tribological engineering materials such as nickel (Ni)-based and
cobalt (Co)-based tribo-alloys.
[0039] An austenitic phase, depicted as austenite 152, is a
high-temperature phase in which the shape memory alloy displays a
high-symmetry, usually cubic crystal lattice structure. The
martensitic phase is a low temperature phase in which the shape
memory alloy displays a low-symmetry, monoclinic variant crystal
lattice structure. As a low-symmetry lattice structure, martensite
includes several variants such as detwinned martensite 154 and
twinned martensite 156. A martensitic phase transformation
characterizes the phase transformations between martensite and
austenite. As those skilled in the art will appreciate, the
martensitic phase transformation includes a shear-dominant
diffusionless solid-state phase transformation that occurs by
nucleation and growth. More specifically, the martensitic phase
transformation possesses several well-defined characteristics. The
phase transformation is associated with an inelastic deformation of
the crystal lattice that results from a cooperative and collective
motion of atoms on distances smaller than the lattice parameters.
Accordingly, the phase transformation is substantially
instantaneous and characterized by an absence of diffusion. Both
phases of the shape memory alloy, however, can coexist during the
phase transformation. An invariant plane having well defined mutual
orientation relationships, which are alloy specific, partitions the
phases from one another.
[0040] As illustrated in the stress-temperature phase diagram, the
austenite-to-martensite phase transformation occurs once the free
energy of martensite becomes less than the free energy of austenite
at a temperature below a critical temperature T.sub.0 (not
illustrated) at which the free energies of the two phases are
equal. The phase transformation does not begin exactly at the
critical temperature T.sub.0, however. In the absence of stress,
the phase transformation begins at a martensite start temperature,
denoted M.sup.0s 158, which is less than T.sub.0, and continues to
evolve as the temperature is lowered until a martensite finish
temperature, denoted M.sup.0f 160, is reached.
[0041] Similarly, when the shape memory alloy is heated in the
absence of stress from martensite, the martensite-to-austenite
phase transformation begins at a austenite start temperature,
denoted A.sup.0s 162, and the material is fully austenite at an
austenite finish temperature, denoted A.sup.0f 164. Hence, the
martensite-to-austenite transformations exhibit a hysteresis and a
dependence on the direction of the temperature change. Moreover,
the difference between the transition temperatures is related to
the critical temperature, T.sub.0, which may be approximated as
follows: (M.sup.0s+A.sup.0f)/2
[0042] Shape memory alloys exhibit the shape memory effect during
austenite-to-martensite-to-austenite loading paths. More
specifically, when a stress or load is applied to the shape memory
alloy, the shape memory alloy is transformed from austenite to
martensite. Upon a subsequent heating to a temperature .E-backward.
A.sup.0f, the shape memory alloy returns to austenite. Shape memory
alloy also exhibits pseudoelasticity, which is a property that is
similar to the shape memory effect and encompasses both
superelastic and rubberlike behavior. More particularly, when a
stress or load is applied to the shape memory alloy, the shape
memory alloy is transformed from austenite to martensite. Upon a
subsequent heating to a temperature .E-backward. A.sup.0s, a
partial strain recovery of the shape memory alloy occurs. The phase
transformations of the shape memory alloy are the basis for the
shape memory effect and pseudoelasticity properties that make the
shape memory alloy resistant to erosive stresses.
[0043] Additional properties, such as thermal stability and
corrosion resistance, of shape memory alloys are presented in the
following table wherein a Titanium nickel (TiNi) alloy is presented
by way of example: TABLE-US-00001 TABLE 1 Physical Properties of
TiNi Property Austenite Martensite Melting Temperature, EC 1300
1300 Density, g/cm.sup.3 6.45 6.45 Resistivity, .phi..OMEGA./cm
Approx. 100 Approx. 70 Thermal Conductivity, wEC/cm 18 8.5
Corrosion Resistance Similar to 300 Similar to 300 series series
stainless stainless steel or steel or titanium titanium alloys
alloys Yield Strength, Mpa (ksi) 195 to 690 70 to 140 (28 to 100)
(10 to 20) Ultimate Tensile Strength, Mpa (ksi) 895 (130) 895 (130)
Transformation Temperatures, EC -200 to 110 -200 to 110 Latent Heat
of Transformation, 167 (40) 167 (40) KJ atom/kg (cal atom/g) Shape
Memory Strain Approx. 1.5 to Approx. 1.5 to Approx. 8.5% Approx.
8.5%
[0044] The properties of the shape memory material may be further
influenced by cold working the material which refines the grain
size and orients the direction of the grains, thereby improving the
crystallographic orientation of the grains and the erosion
behavior. Cold working may be done when the material is in a billet
form, a partially formed shape (e.g., sheet form) or after the
final shaping of the material has been accomplished.
[0045] Referring now to FIG. 6, therein is depicted an
austenite-to-martensite-to-austenite shape memory alloy phase
transformation in panels 180 through 186. As illustrated in panel
180, a tool 188, such as the downhole fluid flow control device
illustrated in FIGS. 3A, 3B and 4, includes a surface 190 having a
shape memory material, such as shape memory alloy 192, integrated
therewith. While the shape memory alloy 192 is depicted as a layer
on surface 190 for purposes of explanation, it should be
appreciated by those skilled in the art that shape memory alloy 192
may form the entire component and not just the surface of tool 188.
Initially, an ambient temperature .E-backward. A.sup.0f is present
about tool 188 as indicated by the expression T .E-backward.
A.sup.0f. Accordingly, as previously discussed, at temperature
.E-backward. A.sup.0f, shape memory alloy 192 is in austenitic
phase as represented by austenite 194 in the enlarged
representation of shape memory alloy 192. In panel 182, tool 188
and, in particular, shape memory alloy 192 is subjected to an
erosive stress as represented by arrow 196. As previously
discussed, the erosive stress may be a moving fluid, erosive agent
such as particulate matter or mechanical stress that causes erosion
by friction. In panel 184, the erosive stress is continuing as
indicated by arrow 198. Further, the sustained erosive stress is
sufficient to transform the phase of shape memory alloy 192 from
austenite 194 to detwinned martensite 200. In particular
implementations, it should be appreciated that the sustained
erosive stress generates heat which furthers the phase
transformation in accordance with the transition diagram presented
in FIG. 5. In panel 186, the erosive stress is concluded and the
ambient temperature .E-backward. A.sup.0f persists proximate to
tool 188. The ambient temperature heats shape memory alloy 192 to a
temperature .E-backward. A.sup.0f, thereby returning shape memory
alloy 192 to austenite 194. Hence, tool 188 having shape memory
alloy 192 absorbed erosive stress without exhibiting erosive wear
by executing a reversible phase transformation.
[0046] Referring now to FIG. 7, therein is depicted an
austenite-to-martensite-to-austenite shape memory alloy phase
transformation in panels 200 through 208. As illustrated in panel
200, a tool 210 includes a surface 212 having a shape memory alloy
214 integrated therewith that is subjected to erosion. Initially,
shape memory alloy 214 is austenite 216 and shape memory alloy 214
is being subjected to an erosive stress as represented by arrow
218. In panel 202, the erosive stress continues as indicated by
arrow 220. The continued stress transforms shape memory alloy 214
from austenite 216 to detwinned martensite 222. In panel 204, the
erosive stress has stopped and shape memory alloy 214 remains in
martensitic phase 222. Further, as illustrated, a heat source 224
applies heat 226 to shape memory alloy 214 in order to heat the
shape memory alloy and effectuate the martensite-to-austenite
transformation. The heat source may be a power generator, friction
heater, electric line, fuel generator, resistance heater,
radioactive source or other downhole or surface heat source. In
panel 208, the temperature of shape memory alloy 214 has been
increased to a temperature .E-backward. A.sup.0f and martensite 222
has transformed into austenite 216.
[0047] Referring now to FIG. 8, therein is depicted a
martensite-to-austenite-to-martensite-to-austenite-to-martensite
shape memory alloy phase transformation in panels 230 through 240.
More particularly, a tool 242 includes a surface 244 having a shape
memory alloy 246 that is subject to erosive stress. Initially,
shape memory alloy 246 is detwinned martensite 248 in an
environment having a temperature # M.sup.0f. In panel 232, a heat
source 250 applies heat 252 in order to raise the temperature to a
temperature .E-backward. A.sup.0f and transform detwinned
martensite 248 to austenite 254, which is depicted in panel 234. In
one embodiment, heat source 250 may be utilized periodically to
remove residual stress that accumulates from excessive stress such
as erosion.
[0048] In addition to heating, it should be appreciated that in
certain situations it may desirable to cool shape memory alloy 246
as well using a refrigerator with thermal cycles or solid state
thermoelectric device, for example. In one implementation, a
dissolvable component may be used and it may be desirable to erode
the component. For example, if the ambient temperature is higher
than the phase transformation temperature of the dissolvable
component having a shape memory material in accordance with the
present invention, the dissolvable component may be cooled to
effectuate a phase transformation and the dissolution of the
component
[0049] Furthermore, in panel 234, tool 242 is subjected to an
erosive stress, as indicated by arrow 256, which continues in panel
236, as indicated by arrow 258. The continued erosive stress has
transformed the austenite 254 to detwinned martensite 248. In panel
238, the erosive stress has ceased and the temperature of tool 242
is above A.sup.0f. Hence, the detwinned martensite 248 transforms
into austenite 254. In panel 240, the temperature has fallen to
less than M.sup.0f and austenite 254 returns to detwinned
martensite 248.
[0050] While this invention has been described with reference to
illustrative embodiments, this description is not intended to be
construed in a limiting sense. Various modifications and
combinations of the illustrative embodiments as well as other
embodiments of the invention, will be apparent to persons skilled
in the art upon reference to the description. It is, therefore,
intended that the appended claims encompass any such modifications
or embodiments.
* * * * *