Shape-memory actuator for use in subterranean wells

The present invention is a wellbore tool which includes as a component an actuator which is composed at least in-part of a shape-memory material characterized by having a property of switching between a deformed shape and a pre-deformed shape upon receipt of thermal energy of a preselected amount. The wellbore tool further includes a component which is movable in position relative to a wellbore tubular conduit into a selected one of a plurality of configurations. The plurality of configurations include a first configuration with the first component in a first position relative to the wellbore tubular conduit, and corresponding to a first mode of operation of the wellbore tool. The plurality of configurations also includes a second configuration with the first component in a second position relative to the wellbore tubular conduit, and corresponding to a second mode of operation in the wellbore tool. The first and second components are physically linked in a manner to transfer motion of a second portion to the first portion. Means is provided for selectively providing thermal energy to at least the second component in an amount of at least the preselected amount of thermal energy required to cause the second portion to switch between the deformed shape and the predeformed shape, resulting in the first component moving from the first position to the second position to urge the wellbore tool from the first mode of operation to the second mode of operation.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to actuators used in subterranean 
wellbores, and specifically to actuators for use with subterranean 
wellbore tools which are operable in a plurality for operating modes and 
switchable between selected operating modes by application of axial force. 
2. Description of the Prior Art 
A variety of conventional wellbore tools which seal, pack, hang, and 
connect with or between concentrically nested wellbore tubular members are 
set into position by application of axial forces to the tool, such as, for 
example, by either lifting up on a tubular string to lessen the load on a 
tool, or by applying a selected amount of set down weight to the tubular 
string, to cause selected components to move relative to one another. For 
example, liner hangers frequently include slip and cone assemblies which 
are loaded to cause a portion of the assembly to come into gripping 
engagement with a selected wellbore surface. For alternative example, 
packers frequently include elastomeric sleeves which are compressed and 
energized to urge the sleeve into sealing engagement with a selected 
wellbore surface. 
Of course, these types of wellbore tools require that operations usually 
performed at the surface cause an intended effect at a remote location 
deep within the wellbore, and in particular require that axial force be 
transferred effectively over great distances, even in difficult wellbores, 
such as deviated or spiral-shaped wellbores. Those knowledgeable about 
wellbore completion operations will appreciate that a force-transmitting 
tubular string may contact other wellbore tubulars or wellbore surfaces at 
a number of locations, dissipating the axial setting force which is 
intended for application at another location, and frustrating completion 
operations. 
Another related problem with the prior art devices is that the wellbore 
tool may be unintentionally subjected to axial, or other, loads during 
running of the tool into the wellbore, which may cause unintentional 
setting of the tool in an undesirable or unintended location. Since many 
wellbore tools, such as liner hangers or packers, are designed to 
permanently lock in a set position, such as accidental setting can result 
in extremely expensive and time-consuming retrieval operations. 
In prior art devices, the interconnected components which are intended, and 
engineered, to provide a permanent lock may, themselves, present operating 
problems, once the tool is disposed at a desired location within the 
wellbore, since they may either fail to operate properly during setting 
procedures, or to operate for the duration of the intended "life" of the 
tool. Failures can occur for a number of reasons, most of which are 
attributable to the harsh wellbore environments frequently encountered. 
The unsetting of wellbore tools which are intended for permanent placement 
can have disastrous financial and engineering consequences. 
SUMMARY OF THE INVENTION 
It is one objective of the present invention to provide an actuator device 
for use in subterranean wellbores which provides an extremely-high, 
localized, preselected axial setting force level. 
It is another objective of the present invention to provide an actuator 
device for use in a subterranean wellbore which is conveyed within a 
wellbore on wellbore tubular members, but which is insensitive to axial 
loading, or other loading, of the wellbore tubular member, and is thus 
unlikely to become unintentionally or inadvertently triggered. 
It is still another objective of the present invention to provide an 
actuator device which is thermally triggered to move between operating 
positions, but which is insensitive to ambient temperatures typically 
encountered within wellbores. 
It is yet another objective of the present invention to provide an actuator 
device for use in subterranean wellbores, which is irreversibly urged 
between pre-actuation and post-actuation positions. 
It is still another objective of the present invention to provide an 
actuator device for use in a subterranean wellbore which depends upon a 
single moving part in moving between pre-actuation and post-actuation 
conditions. 
It is yet another objective of the present invention to provide an actuator 
device for use in a subterranean wellbore which includes a 
forcetransmitting member which maintains a substantially constant force 
level without reliance upon mechanical linkages, connections, or 
couplings, thus providing a force level which is not dependent upon the 
integrity or longevity of linkages, connections, or couplings as are prior 
art wellbore actuators. 
These and other objectives are achieved as is now described. The present 
invention is a wellbore tool which includes a first component an actuator 
which is composed at least in-part of a shape-memory material, which is a 
material characterized by having a property of switching between a 
deformed shape and a pre-deformed shape upon receipt of themal energy of a 
preselected amount. The wellbore tool further includes a second component 
which is movable in position relative to a wellbore tubular conduit into a 
selected one of a plurality of configurations. The plurality of 
configurations include a first configuration with the first component in a 
first position relative to the wellbore tubular conduit, such position 
corresponding to a first mode of operation of the wellbore tool. The 
plurality of configurations also includes a second configuration with the 
first component in a second position relative to the wellbore tubular 
conduit, such position corresponding to a second mode of operation in the 
wellbore tool. The first the second components are physically linked in a 
manner to transfer motion of the second portion to the first portion. 
Means is provided for selectively providing thermal energy to at least the 
second component in an amount of at least the preselected amount of 
thermal energy required to cause the second portion to switch between the 
deformed shape and the predeformed shape, resulting in the first component 
moving from the first position to the second position to urge the wellbore 
tool from the first mode of operation to the second mode of operation. 
In the preferred embodiment of the present invention, the wellbore tool 
includes at least one heating channel disposed within the shape-memory 
material, and a selectively-activated exothermeric substances disposed 
within the heating channel. In this particular embodiment, the means for 
selectively providing thermal energy comprises a device for selectively 
activating the exothermic substance to release thermal energy in an amount 
of at least the preselected amount, causing the second component to switch 
between deformed and pre-deformed shapes. 
Additional objectives, features and advantages will be apparent in the 
written description which follows.

DETAILED DESCRIPTION OF THE INVENTION 
In FIG. 1 wellbore tool 11 is shown disposed within wellbore 9, and 
includes a number of components which are annular in shape and disposed 
about longitudinal axis 13. To simplify the depiction of the preferred 
embodiment of the present invention, FIGS. 1a and 1b are longitudinal 
section views of one-half of wellbore tool 11, which is in actuality 
symmetrical about longitudinal axis 13. In addition, FIGS. 1a and 1b 
should be read together, with FIG. 1a representing the uppermost portion 
of wellbore tool 11, and FIG. 1b representing the lowermost portion of 
wellbore tool 11. As shown in these figures, wellbore tool 11 is 
especially suited for use in a wellbore having a plurality of 
concentrically-nested tubular members therein. For purposes of simplicity, 
FIGS. 1a and 1b show only wellbore tubular conduit 15 disposed within 
wellbore 9, but the concepts of the present invention are equally 
applicable to wellbores which include a greater number of concentrically 
nested tubular members. As shown, wellbore tool 11 of the present 
invention itself includes at least one additional wellbore tubular member. 
All tubular members shown in FIGS. 1a and 1b can comprise lengthy strings 
of tubular members which extend deep into wellbore 9 from the earth's 
surface. 
Preferred wellbore tool 11 of the present invention includes cylindrical 
mandrel 21 which is preferably coupled at its uppermost and lowermost ends 
to other tubular members, together comprising a tubular string which 
extends upward and downward within wellbore 9. FIG. 1b depicts one of such 
couplings, namely threaded coupling 55 between the lowermost end of 
cylindrical mandrel 21 and wellbore tubular conduit 23. 
One particular application of the preferred embodiment of wellbore tool 11 
would be as a component in a liner hanging assembly, in which wellbore 
tubular conduit 15 is a string of casing which extends into wellbore 9 
with cylindrical mandrel 21 being one component in a liner hanger 
assembly, which functions to grippingly and sealingly engage wellbore 
surface 17 of the casing. However, it is not intended that the present 
invention be limited in application to liner hanger assemblies. 
With continued reference to FIGS. 1a and 1b, as shown, the tubing string 
which includes cylindrical mandrel 21 and wellbore tubular conduit 23 
includes inner and outer cylindrical surfaces 57, 59, with inner surface 
57 defining central bore 31 which allows fluids to pass upward and 
downward within wellbore 9. A narrow annular region 25 is provided between 
wellbore tubular conduit 15 and cylindrical mandrel 21. It is one 
objective of the preferred embodiment of the present invention to provide 
for sealing engagement between cylindrical mandrel 21 and wellbore tubular 
conduit 15, with wedge-set sealing flap 35 in sealing engagement with 
wellbore tubular conduit 15 to prevent the passage of fluid (that is, 
broadly speaking, both liquids and gasses) between upper and lower annular 
regions 27, 29. 
Preferably, wedge-set sealing flap 35 is operable in a plurality of modes, 
including a radially-reduced running mode (which is depicted in FIGS. 1a 
and 1b) and a radially-expanded sealing mode with wedge-set sealing flap 
35 urged into sealing contact with inner surface 61 of wellbore tubular 
conduit 15, as is shown in the partial longitudinal section view of FIG. 
3. In the preferred embodiment of the present invention, wedge-set sealing 
flap 35 is integrally formed in cylindrical mandrel 21, which includes a 
radially-reduced portion 49 and radially-enlarged portion 50. Sealing flap 
53 extends radially outward from the portion of radially-reduced portion 
49. Preferably, annular cavity is formed between sealing flap 53 and 
radially-reduced portion 49. 
Wedge-set sealing flap 35 is moved between the radially-reduced running 
position and the radially-enlarged sealing position by operation of 
shape-memory actuator 33. Viewed broadly, shaped-memory actuator 33 
includes first component 45 which is movable relative to radially-reduced 
portion 49 into a selected one of a plurality of configurations, including 
at least a first configuration with the first component 45 in a first 
position relative to cylindrical mandrel 21 corresponding to the running 
mode of operation of wellbore tool 11, and a second configuration with 
first component 45 in a second position relative to cylindrical mandrel 21 
corresponding to a sealing mode of operation of wellbore tool 11. 
Shape-memory actuator 33 further includes a second component 47 which at 
least in-part includes a shape-memory material characterized by having a 
property of switching between a deformed shape and pre-deformed shape upon 
receipt of thermal energy of a preselected amount. In the preferred 
embodiment described herein, first and second components 45, 47 are 
axially aligned along radially-reduced portion 49 of cylindrical mandrel 
21, and are not coupled or linked together. However, in alternative 
embodiments, first and second components 45, 47 may be integrally formed, 
or otherwise coupled or linked together, in a manner to ensure transfer of 
motion of second component 47 to first component 45 to accomplish the 
setting of wedge-set sealing flap 35 against wellbore tubular conduit 15, 
providing a high-integrity seal between upper and lower annular regions 
27, 29. In still other alternative embodiments, both first and second 
components 45, 47 may be formed of shape-memory material. 
The wellbore tool of the present invention requires a mechanism for 
providing thermal energy to shape-memory actuator 33, which will now be 
described. As shown in FIGS. 1a and 1b, second component 47 of 
shape-memory actuator 33 has at least one heating channel 63 disposed 
therein, and filled with a selectively-activated exothermic substance 65. 
The preferred embodiment of the present invention of wellbore tool 11 is 
more clearly depicted in FIG. 2, which is a fragmentary perspective view 
of a portion of the preferred embodiment of the shape-memory actuator 33 
of the present invention, with portions depicted in cut-away and phantom 
view. As shown, second component 47 of shape-memory actuator 33 is 
cylindrical in shape, and is preferably formed at least in-part of 
shape-memory material 67. A plurality of axially-aligned heating channels 
63 are provided within the shape-memory material 67 of second component 47 
and are arranged in a balanced configuration with each channel being 
spaced a selected radial distance from adjacent heating channels 63. An 
annular groove 69 is provided at the lowermost end of second component 47 
of shape-memory actuator 33, and is adapted for also receiving 
selectively-activated exothermic substance 65, and thus linking each of 
the plurality of heating channels 63 to one another. In the preferred 
embodiment, selectively-activated exothermic substance 65 comprises strong 
oxidizing compounds, fuels, and fillers, similar to that which is 
ordinarily found in road flares and solid fuel rocket engines, and which 
can be used to selectively heat second component 47 above 300 degrees 
Fahrenheit, as will be discussed below. The materials which comprise 
shape-memory material 67 will be discussed herebelow in greater detail. 
With reference again to FIGS. 1a and 1b, In the preferred embodiment of the 
present invention, selectively-activated exothermic substance 65 is 
ignited by a conventional heat generating ignitor 71 which is disposed at 
the lowermost end of second component 47 of shape-memory actuator 33 and 
embedded in the selectively actuated exothermic substance 65. Electrical 
conductor 73 is coupled to ignitor 71, and serves to selectively provide 
an electrical actuation signal to ignitor 71 which fires ignitor 71, 
causing an exothermic reaction from selectively-activated exothermic 
substance 65, which generates heat throughout heating channels 63, 
uniformly providing a predetermined amount of thermal energy to the 
shape-memory material 67 of second component 47 of shape-memory actuator 
33. 
Conductor cavity 75 is provided within non-magnetic tool joint 77 which 
includes external threads 41 which couple with internal threads 43 of 
cylindrical mandrel 21. The uppermost portion of non-magnetic tool joint 
77 is concentrically disposed over a portion of the exterior surface of 
cylindrical mandrel 21, forming buttress 79 which is in abutment with the 
lowermost portion of second component 47 of shape-memory actuator 33. 
O-ring seal 81 is provided in O-ring seal groove 83 on the interior 
surface of non-magnetic tool joint 77 to provide a fluid-tight and 
gas-tight seal at the connection of internal and external threads 41, 43. 
Electrical conductor 73 extends downward through conductor cavity 75 to a 
lowermost portion of non-magnetic tool joint 77 and couples to firing 
mechanism 37. 
Firing mechanism 37 includes electromagnetic transmitter portion 85 and 
electromagnetic receiver portion 87, which cooperate to transmit an 
actuation current which serves to energize (and, thus detonate) ignitor 
71, triggering an exothermic reaction from selectively-actuated exothermic 
substance 65. In the preferred embodiment of the present invention, 
electromagnetic transmitter portion 85 comprises permanent magnet 91 which 
is selectively conveyed into position within wellbore 9 on workstring 93, 
for placement in a selected position relative to cylindrical mandrel 21. 
Preferably, workstring 93 is disposed radially inward from cylindrical 
mandrel 21, and is raised and lowered within central bore 31 of the tubing 
string which includes cylindrical mandrel 21. In the preferred embodiment, 
electromagnetic receiver portion 87 comprises a conductor coil 89 which is 
preferably an insulated copper conductive wire which is wound about 
non-magnetic tool joint 39 a plurality of turns, and which is electrically 
coupled to electrical conductor 73. 
Together, ignitor 71, electrical conductor 73, and conductor coil 87 form a 
single electrical circuit. Conductor coil 87 is sensitive to magnetic 
fields generated by rotation of permanent magnet 91, and will generate an 
electric current in response to rotation of workstring 93 relative to 
cylindrical mandrel 21. Preferably, workstring 93 is rotated at a rate of 
between fifty and one hundred revolutions per minute. Conductor coil 89 
need only generate a current sufficient to fire ignitor 71. The current 
may be calculated by conventional means, and depends upon the conductivity 
of the conductor coil 89, the cross-section area of conductor coil 89, the 
number of turns of wire contained in conductor coil 89, and the strength 
of permanent magnet 91. Preferably, a conventional ignitor 71 is employed, 
which requires a known amount of current for effecting firing. The 
requirements of ignitor 71 can be used to work backward to determine the 
design requirements for the gauge of the wire of conductor coil 89, the 
conductivity of the wire of conductor coil 89, the number of turns of 
conductor coil 89, and the strength of permanent magnet 91, and the 
rotation speed required of workstring 93. Permanent magnet 91 may include 
alternating regions of magnetized and non-magnetized material. 
Non-magnetic tool joint 77 is preferably formed of a non-magnetic material 
to allow the magnetic field from permanent magnet 91 to penetrate the tool 
joint, and is preferably formed of Monel. 
The magnetic field produced by rapid rotation of permanent magnet 91 on 
workstring 93 produces a magnetic field which is not usually encountered 
in the wellbore, thus providing an actuation signal which is unlikely to 
be encountered accidentally in the wellbore during run-in operations. 
Firing mechanism 37 is further advantageous in that triggering may be 
performed at the surface by a preselected manipulation of workstring 93. 
Of course, the preselected manipulation (that is, rapid rotation at rates 
of between fifty of one hundred revolutions per minute) is also unlikely 
to be encountered accidentally in the wellbore during run in. Both of 
these features ensure that firing mechanism 37 will not be accidentally 
discharged in an undesirable location within the wellbore. Firing 
mechanism 37 of the present invention is further advantageous in that 
electromagnetic transmitter portion 85 and electromagnetic receiver 
portion 87 are carried into the wellbore mounted in such a way that magnet 
91 is not aligned with receiver 87, until the wellbore tubular conduit 23 
is anchored in the well and workstring 93 is raised or lowered with 
respect to wellbore tubular conduit 23. One way this can be accomplished 
is to carry electromagnetic transmitter portion 85 and electromagnetic 
receiver portion 87 on separate tubing strings. 
With reference again to FIG. 3, the relationship between wedge-set sealing 
flap 35 and shape-memory actuator 33 will be described in detail. As 
discussed above, wedge-set sealing flap 35 is operable in a plurality of 
modes, including a radially-reduced running mode and a radially-expanded 
sealing mode. FIG. 3 is a longitudinal section view of a portion of the 
preferred embodiment of wedge-set sealing flap 35 in a sealing mode of 
operation in sealing engagement with wellbore tubular conduit 15 which is 
disposed radially outward from cylindrical mandrel 21. As shown in FIG. 3, 
sealing flap 53 is integrally formed in cylindrical mandrel 21, and thus 
does not rely upon threaded couplings or other connections for its 
physical placement relative to cylindrical mandrel 21. Sealing flap 53 
overlies a region of radially-reduced portion 49 of cylindrical mandrel 
21. Sealing flap 53 is separated from radially-reduced portion 49 by 
annular cavity 51. 
In the preferred embodiment, upper and lower seal beads 95, 97 are disposed 
on the exterior surface of seal flap 53. Upper and lower seal beads 95, 97 
are raised in cross-section, and extend around the circumference of seal 
flap 53, and serve to sealingly engage inner surface 61 of wellbore 
tubular conduit 15. Thus, wedge-set sealing flap 35 forms a gas-tight 
barrier between upper and lower annular regions 27, 29 which are disposed 
between cylindrical mandrel 21 and wellbore tubular conduit 15. 
In the preferred embodiment, wedge-set sealing flap 35 is urged between the 
radially-reduced running mode of operation and the radially-enlarged 
sealing mode of operation by shape-memory actuator 33. As discussed above, 
shape-memory actuator 33 includes first and second components 45, 47. In 
the preferred embodiment, at least second component 47 is formed of a 
shape-memory material which is urged between a axially-shortened deformed 
position and an axially-elongated pre-deformation condition by application 
of thermal energy to heat shape-memory actuator 33 above a selected 
temperature threshold. In the preferred embodiment, first component 45 
comprises a cylindrical wedge having an inclined outer surface 99 which is 
sloped radially outward from an upper radially-reduced region 101 to a 
lower radially-enlarged region 103. Inclined outer surface 99 is adapter 
for slidably engaging inclined inner surface 105 of wedge-set sealing flap 
35, which is disposed at the lowermost end of wedge-set sealing flap 35 at 
the opening of annular cavity 51. 
When second component 47 of shape-memory actuator 33 is urged between the 
shortened deformed position and the axially-lengthened pre-deformation 
position, first component 45 is urged axially upward into annular cavity 
51, causing inclined outer surface 99 to slidably engage inclined inner 
surface 105 of wedge-set sealing flap 35, to urge wedge-set sealing flap 
35 radially outward to force at least one of upper and lower seal beads 
35, 37 into tight sealing engagement with inner surface 61 of wellbore 
tubular conduit 15. 
In the preferred embodiment of the present invention, cylindrical mandrel 
21 is constructed from 4140 steel. Central bore 31 extends longitudinally 
through cylindrical mandrel 21, and has a diameter of three inches. In the 
preferred embodiment, radially-reduced portion 49 of cylindrical mandrel 
21 has an outer diameter of 4.5 inches, and radially-enlarged portion 50 
of cylindrical mandrel 21 has an outer diameter of 5.5 inches. Preferably, 
annular cavity 51 extends between radially-reduced portion 49 and 
radially-enlarged portion 50 of cylindrical mandrel 21, having a length of 
1.1 inches and a width of approximately 0.2 inches. Preferably, inclined 
inner surface 105 of sealing flap 53 is inclined at an angle of thirty 
degrees from normal. In the preferred embodiment, sealing flap 53 is 
approximately 1.1 inches long, and has a width of 0.3 inches. Also, in the 
preferred embodiment, upper and lower seal beads 95, 97 extend radially 
outward from the exterior surface of sealing flap 53 a distance of 0.04 
inches. As shown in FIG. 5, upper and lower seal beads 95, 97 are 
generally flattened along their outermost surface, and include side 
portions which are sloped at an angle of forty-five degrees from the 
outermost surface of sealing flap 53. 
In the preferred embodiment of the present invention, first component 45 of 
shape-memory actuator 33 is formed of 4140 steel, and includes a central 
bore having a diameter of 4.52 inches, and an outer surface defining an 
outer diameter of 5.5 inches. In the preferred embodiment, first component 
45 is 1.0 inches long, and includes inclined outer surface 99 which is 
sloped at an angle of approximately thirty degrees from normal. Inclined 
outer surface 99 begins at radially-reduced region 101, which has a outer 
diameter of 4.9 inches, in the preferred embodiment, and extends downward 
to radially-enlarged region 103 which has an outer diameter of 5.5 inches. 
It will be appreciate that, at radially-reduced region 101 of first 
component 45 of shape-memory actuator 33, the wedge-shaped member of first 
component 45 will be easily insertable within annular cavity 51, since the 
innermost surface of sealing flap 53 is 4.9 inches in diameter. As first 
component 45 is urged upward within annular cavity 51, inclined outer 
surface 99 and inclined inner surface 105 slidably engage, and sealing 
flap 53 is urged radially outward into gripping and sealing engagement 
with wellbore tubular conduit 15. In the preferred embodiment of the 
present invention, sealing flap 53 is adapted to flex 0.17 inches per 
side. Upper and lower seal beads 95, 97 will engage wellbore tubular 
conduit 15, with at least one of them forming a fluid-tight and gas-tight 
seal with wellbore tubular conduit 15. 
It is one objective of the present invention to employ shape-memory 
actuator 33 to drive first component 45 into annular cavity 51 at a high 
force level, in the range of 150,000 to 500,000 pounds of force. 
Consequently, first component 45 is driven into annular cavity 51 with 
such force that the material of cylindrical mandrel 21, first component 
45, and sealing flap 53 yields, galls, and sticks together, permanently 
lodging first component 45 in a fixed position within annular cavity 51, 
to provide a permanent outward bias to sealing flap 53, keeping it in 
gripping and sealing engagement with wellbore tubular conduit 15. 
In order to accomplish these objectives, at least second component 47 of 
shape-memory actuator 33 is formed of a shape-memory material. This is a 
term which is used to describe the ability of some plastically deformed 
metals and plastics to resume their original shape upon heating. The 
shape-memory effect has been observed in many metal alloys. Shape-memory 
materials are subject to a "thermoelastic martensitic transformation", a 
crystalline phase change that takes place by either twinning or faulting. 
Of the many shape-memory alloys, Nickle-Titanium (Ni-ti) and Copper-based 
alloys have proven to be most commercially viable in useful engineering 
properties. Two of the more common Copper-based shape-memory materials 
include a Copper-Zinc-Aluminum alloy (Cu-Zn-Al) and a 
Copper-Aluminum-Nickle alloy (Cu-Al-Ni). Some of the newer, more-promising 
shape-memory alloys include Iron-based alloys. 
Shape-memory materials are sensitive to temperature changes, and will 
return to a pre-deformation shape from a post-deformation shape, after 
application of sufficient thermal energy to the shape-memory material. A 
shape-memory alloy is given a first shape or configuration, and then 
subjected to an appropriate treatment. Thereafter, its shape or 
configuration is deformed. It will retain that deformed shape or 
configuration until such time as it is subjected to a predetermined 
elevated temperature. When it is subjected to the predetermined elevated 
temperature, it tends to return to its original shape or configuration. 
Heating above the predetermined elevated temperature is the only energy 
input needed to induce high-stress recovery to the original 
pre-deformation shape. The predetermined elevated temperature is usually 
referred to as the transition or transformation temperature. The 
transition or transformation temperature may be a temperature range and is 
commonly known as the transition temperature range (TTR). 
Nickle-based shape-memory alloys were among the first of the shape-memory 
materials discovered. The predominant shape-memory alloy in the 
Nickle-based group is a Nickle-Titanium alloy called Nitinol or Tinel. 
Early investigations on Nitinol started in 1958 by the U.S. Naval 
Ordinance Laboratory which uncovered the new class of novel 
Nickle-Titanium alloys based on the ductile intermetallic compound TiNi. 
These alloys were subsequently given the name Nitinol which is disclosed 
in U.S. Pat. No. 3,174,851, which issued on Mar. 23, 1965, and which is 
entitled Nickle-Based Alloys; others of the early U.S. patents directed to 
the Nickle-based shape-memory alloys include U.S. Pat. No. 3,351,463, 
issued on Nov. 7, 1967, and entitled High Strength Nickle-Based Alloys, 
and U.S. Pat. No. 3,403,238, issued on Sep. 24, 1968, entitled Conversion 
of Heat Energy to Mechanical Energy. All these patents are assigned to the 
United States of America as represented by the Secretary of the Navy, and 
all are incorporated herein by reference as if fully set forth herein. 
Two commercial Copper-based shape-memory alloy systems are: Cu-Cn-Al and 
Cu-Al-Ni. Generally, Copper-based alloys are more brittle than 
Nickle-based alloys. In order to control the grain size, the material must 
be worked in a hot condition. In addition, Copper-based alloys usually 
require quenching to retain the austenitic condition at intermediate 
temperatures, which makes them less stable than the Nickle-based alloys. 
One technical advantage of the Copper-based shape-memory alloys is that 
substantially higher transformation temperatures can be achieved as 
compared with currently available Nickle-based shape-memory alloys. 
Copper-based shape-memory alloys are also less expensive than Nickle-based 
shape-memory alloys. 
The Nickle-based shape-memory alloys can really provide the greatest 
proportionate displacement between pre-deformation and post-deformation 
dimensions. This property is generally characterized as the "recoverable 
strain" of the shape-memory material. Of the commercially available 
shape-memory alloys, the Ni-Ti alloy has a recoverable strain of 
approximately eight percent. The Cu-Cn-Al alloy has a recoverable strain 
of approximately four percent. The Cu-Al-Ni alloy generally has a 
recoverable strain of approximately five percent. 
FIG. 6a depicts a plot of stress versus strain for the physical deformation 
of Nickle-based and Copper-based shape-memory materials. In this graph, 
the X-axis is representative of strain in the material, and the Y-axis is 
representative of stress on material. Portion 141 of the curve depicts the 
stress-strain relationship in the material during a loading phase of 
operation, in which the load is applied to material which is a martensitic 
condition. In the graph, loading is depicted by arrow 143. Portion 145 of 
the curve is representative of the material in a defined martensitic 
condition, during which significant strain is added to the material in 
response to the addition of relatively low amounts of additional stress. 
It is during portion 145 of the curve that the shape-memory material is 
most deformed from a pre-deformation shape to a post-deformation shape. In 
the preferred embodiment of the present invention, it is during this phase 
that second component 47 of shape-memory actuator 33 is physically 
shortened. Portion 147 of the curve is representative of an unloading of 
the material, which is further represented by arrow 149. The shape-memory 
material is an austenite condition. Arrows 151, 153, 155 are 
representative of the response of the material to the application of heat 
sufficient to return the material from the post-deformation shape to the 
pre-deformation shape. In the preferred embodiment of the present 
invention, the operation represented by arrows 151, 153, 157 corresponds 
to a lengthening of second component 47 of shape-memory actuator 33. 
One problem with the use of Nickle-based and Copper-based shape-memory 
materials is that the maximum triggering temperature can be quite low. For 
Nickle-based metal alloys, the maximum triggering temperature for 
commercially available materials is approximately one hundred and twenty 
degrees Celsius. For Copper-based shape-memory alloys, the maximum 
triggering temperature for commercially available materials is generally 
in the range of one hundred and twenty degrees Celsius to one hundred and 
seventy degrees Celsius. This presents some limitation for use of 
Nickle-based shape-memory alloys and Copper-based shape-memory alloys in 
deep wells, which experience high temperatures. Therefore, Nickle-based 
shape-memory alloys and Copper-based shape-memory alloys may be limited in 
wellbore use to rather shallow, or low-temperature applications. 
The Iron-based shape-memory alloys include three main types: 
Iron-Manganese-Silicon; Iron-Nickle-Carbon; and 
Iron-Manganese-Silicon-Nickle-Chrome. 
In the preferred embodiment of the present invention, second component 47 
of shape-memory actuator 33 is composed of an 
Iron-Manganese-Silicon-Nickle-Chrome shape-memory alloy which is 
manufactured by Memry Technologies, Inc. of Brookfield, Conn. In the 
preferred embodiment, shape-memory alloy has a following composition by 
percentage of weight: Manganese (Mn): 13.8%; Silicon (Si): 6%; Nickle 
(Ni): 5%; Chrome (Cr): 8.4%; Iron (Fe): balance. However, in alternative 
embodiments, Nickle-based shape-memory alloys and Copper-based 
shape-memory alloys may be used. Several types are available commercially 
from either Memry Technologies, Inc. of Brookfield, Conn., or Raychem 
Corporation of Menlow Park, Calif. 
In the preferred embodiment of the present invention, second component 47 
of shape-memory actuator 33 is approximately six feet long, and is in a 
cylindrical shape, with an inner diameter of 3.5 inches, and an outer 
diameter of 5.5 inches. The inner and outer diameters define the 
cross-sectional area with which second component 47 engages first 
component 45 in shape-memory actuator 33, and consequently controls the 
amount of force which may be applied to first component 45. 
The Iron-based shape-memory alloys work differently from the Nickle-based 
alloys and Copper-based alloys, as set forth in flowchart form in FIG. 7. 
In step 201 the austenite phase is obtained as a starting point. The 
material in the austenite phase is subjected to deformation is step 203 to 
obtain a stress-induced martensite phase, as shown in step 205. Heat is 
applied (over 300 degrees Fahrenheit, preferably) in step 207 which causes 
second component 47 of shape-memory actuator 33 to return to the austenite 
phase in step 209, yield an axial force in step 210 and simultaneously 
regain shape in step 211. 
In the preferred embodiment of the present invention, at these steps, 
second component 47 regains approximately one to two percent of its 
original length, resulting in the application of a force of approximately 
one hundred and fifty thousand pounds to first component 45, urging it 
into annular cavity 51. In step 213, second component 47 of shape-memory 
actuator 33 cools, resulting in a slight decrease, in step 215, in the 
force applied by second component 47 to first component 45. This decrease 
in force will be insignificant. 
FIG. 6b is a graphic depiction of the stress-strain curve for an iron-based 
shape-memory alloy. In this graph, the X-axis is representative of strain, 
and the Y-axis is representative of stress. Portion 163 of the curve is 
representative of the shape-memory alloy in the austenite phase. Load 
which is applied to the shape-memory alloy is represented by arrow 161. 
Loading of the shape-memory material causes it to transform into a 
stress-induced martensite which is represented on the curve by portion 
165. The release of loading is represented by arrow 167. Portion 169 of 
the curve is representative of application of heat to the material, which 
causes it to return to the austenite phase. The return of the austenite 
phase is represented by arrows 171, 173, and 175. 
FIGS. 4a through 4d are longitudinal section views of portions of the 
preferred embodiment of the wellbore tool of the present invention, in 
time sequence order, to depict the setting of wedge-set sealing flap 35. 
Beginning in FIG. 4a, workstring 93 is lowered into a desired position 
within central bore 31 of cylindrical mandrel 21. Workstring 93 is rotated 
at a rate of between 90 and 100 revolutions per minute, causing permanent 
magnet 91 to rotate and generate a magnetic field which is picked up by 
conductor coil 89. Consequently, an electric current is caused to flow 
through electrical conductor 73 to ignitor 71 which is lodged in the 
selectively-activated exothermic substance 65 of a selected heating 
channel 63, as shown in FIG. 4b. The current causes ignitor 71 to be 
actuated triggering an exothermic reaction in selectively actuated 
exothermic substance 65, which heats second component 47 of shape-memory 
actuator 33 to a temperature above the transformation temperature. 
As shown in FIG. 4c, as a consequence of this heating, second component 47 
is lengthened a selected amount 107. As shown in FIG. 4d, lengthening of 
second component 47 of shape-memory actuator 33 causes first component 45 
to be driven axially upward and into annular cavity 51, where it causes 
sealing flap 53 to be flexed radially outward from a radially-reduced 
running position to a radially-expanded sealing position, with at least 
one of upper and lower seal beads 95, 97 in sealing and gripping 
engagement with inner surface 61 of wellbore tubular conduit 15. First 
component 45 is in fact interference fit into annular cavity 51, and thus 
the materials of sealing flap 53, first component 45, and radially-reduced 
portion 49 may gall or fuse together to place first component 45 in a 
fixed position within annular cavity 51. Of course, second component 47 of 
shape-memory actuator 33 will continue to exert a substantial force 
against first components 45, even after cooling occurs, and thus will 
serve as a buttress preventing downward movement of first component 
relative to annular cavity 51, should the components fail to fuse 
together. 
While the invention has been shown in only one of its forms, it is not thus 
limited but is susceptible to various changes and modifications without 
departing from the spirit thereof.