CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Application Serial No. 17/326,723, filed on May 21, 2021, entitled “A WELLBORE ANCHOR INCLUDING ONE OR MORE ACTIVATION CHAMBERS,” commonly assigned with this application and incorporated herein by reference in its entirety.

BACKGROUND

[0002] Multilateral wells include one or more lateral wellbores extending from a main wellbore. A lateral wellbore is a wellbore that is diverted from the main wellbore. A multilateral well may include one or more windows or casing exits to allow corresponding lateral wellbores to be formed. The window or casing exits for multilateral wells are typically formed by positioning (e.g., anchoring) one or more whipstock assemblies in a casing string with a running tool at desired locations in the main wellbore. In some embodiments, whipstocks may be used to deflect a window mill relative to the casing string. The deflected window mill penetrates part of the casing joint to form the window or casing exit in the casing string and is then withdrawn from the wellbore. Downhole assemblies can be subsequently inserted through the casing exit in order to cut the lateral wellbore, fracture the lateral wellbore, and/or service the lateral wellbore.

BRIEF DESCRIPTION

[0003] Reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0004] FIG. 1 is a schematic view of a well system according to one or more embodiments disclosed herein;

[0005] FIGs. 2A and 2B illustrate one embodiment of an anchor designed and manufactured according to one or more embodiments of the disclosure;

[0006] FIGs. 3A and 3B illustrate another embodiment of an anchor designed and manufactured according to one or more embodiments of the disclosure; and

[0007] FIGs. 4A and 4B illustrate yet another embodiment of an anchor designed and manufactured according to one or more embodiments of the disclosure. DETAILED DESCRIPTION

[0008] In the drawings and descriptions that follow, like parts are typically marked throughout the specification and drawings with the same reference numerals, respectively. The drawn figures are not necessarily to scale. Certain features of the disclosure may be shown exaggerated in scale or in somewhat schematic form and some details of certain elements may not be shown in the interest of clarity and conciseness. The present disclosure may be implemented in embodiments of different forms.

[0009] Specific embodiments are described in detail and are shown in the drawings, with the understanding that the present disclosure is to be considered an exemplification of the principles of the disclosure, and is not intended to limit the disclosure to that illustrated and described herein. It is to be fully recognized that the different teachings of the embodiments discussed herein may be employed separately or in any suitable combination to produce desired results. [0010] Unless otherwise specified, use of the terms “connect,” “engage,” “couple,” “attach,” or any other like term describing an interaction between elements is not meant to limit the interaction to direct interaction between the elements and may also include indirect interaction between the elements described.

[0011] Unless otherwise specified, use of the terms “up,” “upper,” “upward,” “uphole,” “upstream,” or other like terms shall be construed as generally toward the surface of the ground; likewise, use of the terms “down,” “lower,” “downward,” “downhole,” or other like terms shall be construed as generally toward the bottom, terminal end of a well, regardless of the wellbore orientation. Use of any one or more of the foregoing terms shall not be construed as denoting positions along a perfectly vertical axis. Unless otherwise specified, use of the term “subterranean formation” shall be construed as encompassing both areas below exposed earth and areas below earth covered by water such as ocean or fresh water.

[0012] FIG. 1 is a schematic view of a well system 100 according to one or more embodiments disclosed herein. The well system 100 includes a platform 120 positioned over a subterranean formation 110 located below the earth’s surface 115. The platform 120, in at least one embodiment, has a hoisting apparatus 125 and a derrick 130 for raising and lowering pipe strings, such as a drill string 140. Although a land-based oil and gas platform 120 is illustrated in FIG. 1, the scope of this disclosure is not thereby limited, and thus could potentially apply to offshore applications. The teachings of this disclosure may also be applied to other land-based well systems different from that illustrated.

[0013] As shown, a main wellbore 150 has been drilled through the various earth strata, including the subterranean formation 110. The term “main” wellbore is used herein to designate a wellbore from which another wellbore is drilled. It is to be noted, however, that a main wellbore 150 does not necessarily extend directly to the earth's surface, but could instead be a branch of yet another wellbore. A casing string 160 may be at least partially cemented within the main wellbore 150. The term “casing” is used herein to designate a tubular string used to line a wellbore. Casing may actually be of the type known to those skilled in the art as a “liner” and may be made of any material, such as steel or composite material and may be segmented or continuous, such as coiled tubing. The term “lateral” wellbore is used herein to designate a wellbore that is drilled outwardly from its intersection with another wellbore, such as a main wellbore. Moreover, a lateral wellbore may have another lateral wellbore drilled outwardly therefrom.

[0014] A whipstock 170 according to one or more embodiments of the present disclosure may be positioned at a location in the main wellbore 150. Specifically, the whipstock 170 could be placed at a location in the main wellbore 150 where it is desirable for a lateral wellbore 180 to exit. Accordingly, the whipstock 170 may be used to support a milling tool used to penetrate a window in the main wellbore 150, and once the window has been milled and a lateral wellbore 180 formed, in some embodiments, the whipstock 170 may be retrieved and returned uphole by a retrieval tool, in some embodiments in only a single trip.

[0015] In some embodiments, an anchor 190 may be placed downhole in the wellbore 150 to support and anchor downhole tools, such as the whipstock 170, for maintaining the whipstock 170 in place while drilling the lateral wellbore 180. The anchor 190, in accordance with the disclosure, may be employed in a cased region of the wellbore 180 or alternatively in an open- hole region of the wellbore 180. As such, the anchor 190 may be configured to resist at least 6,750 newton meters (Nm) (e.g., about 5,000 lb-ft) of torque. In yet another embodiment, the anchor 190 may be configured to resist at least 13,500 newton meters (Nm) (e.g., about 10,000 lb-ft) of torque, and in yet another embodiment configured to resist at least 20,250 newton meters (Nm) (e.g., about 15,000 lb-ft) of torque. Similarly, the anchor 190 may be configured to resist at least 1814 kg (e.g., about 4,000 lb) of axial force. In yet another embodiment, the anchor 190 may be configured to resist at least 4536 kg (e.g., about 10,000 lb) of axial force, and in yet another embodiment the anchor 190 may be configured to resist at least 6804 kg (e.g., about 15,000 lb) of axial force. The anchor 190 may include, in some aspects, a base pipe and one or more expandable chambers positioned radially about the base pipe. The one or more expandable chambers may be configured to move from a first collapsed state while running in hole, to a second activated state once the anchor is positioned within the wellbore 150.

[0016] In some embodiments, the anchor 190 may be hydraulically activated. Once the anchor 190 reaches a desired location in the wellbore 150, fluid pressure may be applied to the one or more expandable chambers to move the one or more expandable chambers from the first collapsed state to the second activated state and engage a wall of the wellbore 150. The anchor 190 may also include, in some embodiments, an exterior sleeve positioned radially about the one or more expandable chambers. In some aspects, the exterior sleeve may be configured to grip and engage the wall of the wellbore 150 when the one or more expandable chambers are in the second activated state.

[0017] Turning now to FIGs. 2A and 2B, illustrated is one embodiment of an anchor 200 designed and manufactured according to one or more embodiments of the disclosure. FIG. 2A illustrates the anchor 200 in the collapsed state, whereas FIG. 2B illustrates the anchor 200 in the activated state. The anchor 200, in one embodiment, may include a base pipe 205. The base pipe 205, in at least on embodiment, does not include openings connecting the interior of the base pipe with the exterior of the base pipe. However, in yet other embodiments, openings may exist between the interior of the base pipe and the exterior of the base pipe.

[0018] One or more expandable chambers 210 may be positioned radially about the base pipe 205. In at least one embodiment, one or more full donut shaped expandable chamber 210 is positioned about the base pipe 205. In at least one other embodiment, two or more expandable chambers 210 may be positioned radially about the base pipe 205. In some embodiments the two or more expandable chambers 210 may be generally linearly aligned with one another. As used herein, generally linearly aligned may mean the two or more expandable chambers 210 may be linearly aligned within 10 percent of their length. In other embodiments, the two or more expandable chambers 210 may be substantially linearly aligned with each other, wherein the two or more two or more expandable chambers 210 may be linearly aligned within 5 percent of their length. In still other embodiments, the two or more expandable chambers 210 may be ideally linearly aligned, wherein the two or more two or more expandable chambers 210 may be linearly aligned within 1 percent of their length.

[0019] In other embodiments, the two or more expandable chambers may be generally angularly aligned, substantially angularly aligned, or ideally angularly aligned with one another. The term “generally angularly aligned” as used herein, means that the two or more expandable chambers are within 10 degrees of parallel with one another. The term “substantially angularly aligned” as used herein, means that the two or more expandable chambers are within 5 degrees of parallel with one another. The term “ideally angularly aligned” as used herein, means that the two or more expandable chambers are within 2 degrees of parallel with one another.

[0020] The two or more expandable chambers 210 may be configured to move from a first collapsed state shown in FIG. 2A to a second activated state shown in FIG. 2B to engage a wall of a wellbore. In some embodiments, when in the second activated state, the one or more expandable chambers 210 may be operable to handle at least 20.7 Bar (about 300 psi) of internal pressure in the second activated state to engage the wall of a wellbore. In some embodiments, when in the second activated state, the one or more expandable chambers 210 may be operable to handle at least 27.6 Bar (about 400 psi) of internal pressure in the second activated state to engage the wall of a wellbore. In some embodiments, when in the second activated state, the one or more expandable chambers 210 may be operable to handle at least 51.7 Bar (about 750 psi) of internal pressure in the second activated state to engage the wall of a wellbore. In some alternative embodiments, when in the second activated state, the one or more expandable chambers 210 may be operable to handle at least 68 Bar (about 1000 psi) of internal pressure in the second activated state to engage the wall of a wellbore.

[0021] In some embodiments, the anchor 200 may include an exterior sleeve 220, which may be positioned radially about the two or more expandable chambers 210. In certain embodiments, the exterior sleeve 220 may be configured to split apart or deform as the two or more expandable chambers 210 expand into the second activated state such that the exterior sleeve 220 may thereafter engage and dig into the wall of the wellbore.

[0022] The exterior sleeve 220 may include openings 225 therein. The openings 225, in certain embodiments, allow for the exterior sleeve 220 to easily expand. The general size and shape of the openings 225 may vary greatly and remain within the scope of the disclosure. In at least one embodiment, the openings 225 are larger than the opening in a typical sand screen. For example, the openings 225 would have a mesh value of at least about 36 (e.g., 485 pm) or greater. In yet another embodiment, the openings 225 would have a mesh value of at least about 20 (e.g., 850 pm) or greater, or in yet another embodiment the openings 225 would have a mesh value of at least about 10 (e.g., 2,000 pm) or greater.

[0023] The exterior sleeve 220, in certain other embodiments, may include a textured surface on an outer surface thereof for engaging the wall of the wellbore. In certain instances, the textured surface has a plurality of undulations, crenellations, corrugations, ridges, depressions, or other surface variations where the radial amplitude of the surface variation is at least about 1 mm (e.g., about .04 inches). In yet another embodiment, the radial amplitude of the surface variation is at least about 1.25 mm (e.g., about .05 inches), and in yet another embodiment the radial amplitude of the surface variation is between about 1.25 mm (e.g., about .06 inches) and about 25 mm (e.g., about 1.0 inches). Any known or hereafter discovered method for creating the textured surface is within the scope of the disclosure.

[0024] The exterior sleeve 220 may comprise metals, carbide, polymers, and other materials used in downhole tool applications. In some embodiments, the exterior sleeve 220 may also comprise a swellable elastomer on an outer surface thereof in order to engage and grip the wall of the wellbore once the two or more expandable chamber 210 have been expanded to the second activated state. The swellable elastomer, in some aspects, may be activated by temperature alone, fluid existing in the wellbore, completion fluid inserted in to the wellbore, or any combination of the above. In an alternative embodiment, the swellable elastomer may be activated by a dedicated well treatment run to pump the activation fluid to the swellable elastomer.

[0025] In yet other embodiments, the exterior sleeve 220 may comprise an expandable/expanded metal. The expandable metal, in some embodiments, may be chemically activated by reactive fluid (e.g., completion fluid) inserted into the wellbore, and result in expanded metal. The term expandable metal, as used herein, refers to the expandable metal in a pre-expansion form. Similarly, the term expanded metal, as used herein, refers to the resulting expanded metal after the expandable metal has been subjected to reactive fluid, as discussed below. The expanded metal, in accordance with one or more aspects of the disclosure, comprises a metal that has expanded in response to hydrolysis. In certain embodiments, the expanded metal includes residual unreacted metal. For example, in certain embodiments the expanded metal is intentionally designed to include the residual unreacted metal. The residual unreacted metal has the benefit of allowing the expanded metal to self-heal if cracks or other anomalies subsequently arise, or for example to accommodate changes in the tubular or mandrel diameter due to variations in temperature and/or pressure. Nevertheless, other embodiments may exist wherein no residual unreacted metal exists in the expanded metal.

[0026] The expandable metal, in some embodiments, may be described as expanding to a cement like material. In other words, the expandable metal goes from metal to micron-scale particles and then these particles expand and lock together to, in essence, assist in preventing extrusion within the sealing assembly. The reaction may, in certain embodiments, occur in less than 2 days in a reactive fluid and in downhole temperatures. Nevertheless, the time of reaction may vary depending on the reactive fluid, the expandable metal used, and the downhole temperature.

[0027] In some embodiments, the reactive fluid may be a brine solution such as may be produced during well completion activities, and in other embodiments, the reactive fluid may be one of the additional solutions discussed herein. The expandable metal is electrically conductive in certain embodiments. The expandable metal may be machined to any specific size/shape, extruded, formed, cast or other conventional ways to get the desired shape of a metal, as will be discussed in greater detail below. The expandable metal, in certain embodiments has a yield strength greater than about 8,000 psi, e.g., 8,000 psi +/- 50%.

[0028] The hydrolysis of the expandable metal can create a metal hydroxide. The formative properties of alkaline earth metals (Mg - Magnesium, Ca - Calcium, etc.) and transition metals (Zn - Zinc, A1 - Aluminum, etc.) under hydrolysis reactions demonstrate structural characteristics that are favorable for use with the present disclosure. Hydration results in an increase in size from the hydration reaction and results in a metal hydroxide that can precipitate from the fluid.

[0029] The hydration reactions for magnesium is:

Mg + 2H ₂ 0 Mg(OH) ₂ + H ₂ , where Mg(OH) ₂ is also known as brucite. Another hydration reaction uses aluminum hydrolysis. The reaction forms a material known as Gibbsite, bayerite, and norstrandite, depending on form. The hydration reaction for aluminum is:

A1 + 3H ₂ 0 Alices + 3/2 H ₂ . Another hydration reaction uses calcium hydrolysis. The hydration reaction for calcium is:

Ca + 2¾0 Ca(OH) ₂ + H ₂ ,

Where Ca(OH) ₂ is known as portlandite and is a common hydrolysis product of Portland cement. Magnesium hydroxide and calcium hydroxide are considered to be relatively insoluble in water. Aluminum hydroxide can be considered an amphoteric hydroxide, which has solubility in strong acids or in strong bases. Alkaline earth metals (e.g., Mg, CA, etc.) work well for the expandable metal, but transition metals (Al, etc.) also work well for the expandable metal. In one embodiment, the metal hydroxide is dehydrated by the swell pressure to form a metal oxide. [0030] In an embodiment, the expandable metal used can be a metal alloy. The expandable metal alloy can be an alloy of the base expandable metal with other elements in order to either adjust the strength of the expandable metal alloy, to adjust the reaction time of the expandable metal alloy, or to adjust the strength of the resulting metal hydroxide byproduct, among other adjustments. The expandable metal alloy can be alloyed with elements that enhance the strength of the metal such as, but not limited to, Al - Aluminum, Zn - Zinc, Mn - Manganese, Zr - Zirconium, Y - Yttrium, Nd - Neodymium, Gd - Gadolinium, Ag - Silver, Ca - Calcium, Sn - Tin, and Re - Rhenium, Cu - Copper. In some embodiments, the expandable metal alloy can be alloyed with a dopant that promotes corrosion, such as Ni - Nickel, Fe - Iron, Cu - Copper, Co - Cobalt, Ir - Iridium, Au - Gold, C - Carbon, Ga - Gallium, In - Indium, Mg - Mercury, Bi - Bismuth, Sn - Tin, and Pd - Palladium. The expandable metal alloy can be constructed in a solid solution process where the elements are combined with molten metal or metal alloy. Alternatively, the expandable metal alloy could be constructed with a powder metallurgy process. The expandable metal can be cast, forged, extruded, sintered, welded, mill machined, lathe machined, stamped, eroded or a combination thereof.

[0031] Optionally, non-expanding components may be added to the starting metallic materials. For example, ceramic, elastomer, plastic, epoxy, glass, or non-reacting metal components can be embedded in the expandable metal or coated on the surface of the expandable metal. Alternatively, the starting expandable metal may be the metal oxide. For example, calcium oxide (CaO) with water will produce calcium hydroxide in an energetic reaction. Due to the higher density of calcium oxide, this can have a 260% volumetric expansion (e.g., converting 1 mole of CaO may cause the volume to increase from 9.5cc to 34.4cc). In one variation, the expandable metal is formed in a serpentinite reaction, a hydration and metamorphic reaction. In one variation, the resultant material resembles a mafic material. Additional ions can be added to the reaction, including silicate, sulfate, aluminate, carbonate, and phosphate. The metal can be alloyed to increase the reactivity or to control the formation of oxides.

[0032] In certain embodiments, two or more bridging plates 230 may be positioned radially about the two or more expandable chambers 210. The two or more bridging plates 230 may be configured to extend across at least a gap between outer portions of the two or more expandable chambers 210 when the two or more expandable chambers 210 are in the second activated state as shown in FIG. 2B. The two or more bridging plates 230 may be configured, in some aspects to provide support for the exterior sleeve 220 positioned about the two or more expandable chambers 210. While it is illustrated that the two or more bridging plates 230 include openings therein, other embodiments may exist wherein the two or more bridging plates 230 do not include openings therein. Although not shown in the illustrated embodiment, certain embodiments of the two or more bridging plates 230 may include protrusions or a textured surface which may engage the wall of the wellbore, and in some embodiments, the protrusions may extend through openings 225 in the exterior sleeve 220.

[0033] FIGs. 3A and 3B illustrate another embodiment of an anchor 300 designed and manufactured according to one or more embodiments of the disclosure. FIG. 3A illustrates the anchor 300 in the collapsed state, whereas FIG. 3B illustrates the anchor 300 in the activated state. The anchor 300 is similar in many respects to the anchor 200 of FIGs. 2A and 2B. Accordingly, like reference numbers have been used to reference similar, if not identical, features. The anchor 300 differs, for the most part, from the anchor 200, in that one embodiment of an exterior sleeve 220 may include protrusions 335 on an outer surface thereof for engaging a wall of a wellbore. As the two or more expandable chambers 210 are expanded to the second activated state, as shown in FIG. 3B, the exterior sleeve 220 moves radially outward toward the wall of the wellbore and the protrusions 335 may grip into and engage the wall of the wellbore. [0034] FIGs. 4A and 4B illustrate another embodiment of an anchor 400 designed and manufactured according to one or more embodiments of the disclosure. FIG. 4A illustrates the anchor 400 in the collapsed state, whereas FIG. 4B illustrates the anchor 400 in the activated state. The anchor 400 is similar in many respects to the anchor 200 of FIGs. 2A and 2B. Accordingly, like reference numbers have been used to reference similar, if not identical, features. The anchor 400 differs, for the most part, from the anchor 200, in that in this embodiment the two or more expandable chambers 210 may include protrusions 415 on an outer circumference thereof. The protrusions 415 may engage the wall of the wellbore as the two or more expandable chambers 210 are expanded outward to the second activated state, as shown in FIG. 4B. In some embodiments, the protrusions 415 on the outer circumference of the two or more expandable chambers 210 may be configured to protrude through the openings 225 in the exterior sleeve 220 positioned radially about the two or more expandable chambers 210.

[0035] Certain embodiments of an anchor disclosed herein may be constructed and function similar to endurance hydraulic screens (EHS) used in wellbore applications. However, anchors according to one or more embodiments of the disclosure may not need to provide any sand or debris control generally required by EHS and as such, may not include any filter mediums or screen members. For example, the anchor may not include any screen members having a filter medium having a size less than 500 micron.

[0036] Aspects disclosed herein include:

A. An anchor for use with a downhole tool in a wellbore, the anchor including: 1) a base pipe; and 2) one or more expandable chambers positioned radially about the base pipe; 3) wherein the one or more expandable chambers are configured to move from a first collapsed state to a second activated state; and 4) wherein the one or more expandable chambers are operable to handle at least 20.7 Bar of internal pressure in the second activated state to engage a wall of a wellbore.

B. A method for anchoring a downhole tool in a wellbore, the method including: 1) running a downhole tool including an anchor into a wellbore, the anchor including: a) a base pipe; b) one or more expandable chambers positioned radially about the base pipe; c) wherein the one or more expandable chambers are configured to move from a first collapsed state to a second activated state; and d) wherein the one or more expandable chambers are operable to handle at least 20.7 Bar of internal pressure in the second activated state to engage a wall of the wellbore; and 2) applying fluid pressure to the one or more expandable chambers to move the one or more expandable chambers from the first collapsed state to the second activated state and anchor the downhole tool within the wellbore.

C. A well system, the well system including: 1) a wellbore; and 2) a downhole tool including an anchor positioned within the wellbore, the at least one anchor including: a) a base pipe; b) one or more expandable chambers positioned radially about the base pipe; c) wherein the one or more expandable chambers are configured to move from a first collapsed state to a second activated state; and d) wherein the one or more expandable chambers are operable to handle at least 20.7 Bar of internal pressure in the second activated state to engage a wall of a wellbore.

[0037] Aspects A, B, and C may have one or more of the following additional elements in combination: Element 1: wherein the one or more expandable chambers are two or more expandable chambers positioned radially about the base pipe, the two or more expandable chambers generally linearly aligned with one another. Element 2: further comprising an exterior sleeve positioned radially about the two or more expandable chambers. Element 3: wherein the exterior sleeve includes protrusions on an outer surface thereof for engaging the wall of the wellbore. Element 4: wherein the exterior sleeve includes a textured surface on an outer surface thereof for engaging the wall of the wellbore. Element 5: wherein the exterior sleeve comprises a swellable elastomer on an outer surface thereof. Element 6: wherein exterior sleeve comprises an expandable metal. Element 7: wherein the two or more expandable chambers include protrusions on an outer circumference thereof, the protrusions for engaging the wall of the wellbore. Element 8: wherein the protrusions on the outer circumference of the two or more expandable chambers are configured to protrude through openings in an exterior sleeve positioned radially about the two or more expandable chambers. Element 9: further comprising two or more bridging plates positioned radially about the two or more expandable chambers, wherein the two or more bridging plates are configured to extend across at least a gap between outer portions of the two or more expandable chambers in the second activated state. Element 10: wherein the anchor does not include a screen member having a filter medium having a size less than 36 mesh. Element 11: wherein the one or more expandable chambers are two or more expandable chambers positioned radially about the base pipe, the two or more expandable chambers generally linearly aligned with one another. Element 12: wherein the anchor further includes an exterior sleeve positioned radially about the two or more expandable chambers. Element 13: wherein the exterior sleeve includes protrusions on an outer surface thereof for engaging the wall of the wellbore. Element 14: wherein the two or more expandable chambers include protrusions on an outer circumference thereof, the protrusions for engaging the wall of the wellbore. Element 15: wherein the protrusions on the outer circumference of the two or more expandable chambers are configured to protrude through openings in an exterior sleeve positioned radially about the two or more expandable chambers. Element 16: further comprising two or more bridging plates positioned radially about the two or more expandable chambers, wherein the two or more bridging plates are configured to extend across at least a gap between outer portions of the two or more expandable chambers in the second activated state. Element 17: wherein the one or more expandable chambers are two or more expandable chambers positioned radially about the base pipe, the two or more expandable chambers generally linearly aligned with one another. Element 18: wherein the anchor further includes an exterior sleeve positioned radially about the two or more expandable chambers. Element 19: wherein the exterior sleeve includes protrusions on an outer surface thereof for engaging the wall of the wellbore. Element 20: wherein the exterior sleeve includes a textured surface on an outer surface thereof for engaging the wall of the wellbore. Element 21: wherein the two or more expandable chambers include protrusions on an outer circumference thereof, the protrusions for engaging the wall of the wellbore and wherein the protrusions on the outer circumference of the two or more expandable chambers are configured to protrude through openings in an exterior sleeve positioned radially about the two or more expandable chambers. Element 22: wherein the anchor further includes two or more bridging plates positioned radially about the two or more expandable chambers, wherein the two or more bridging plates are configured to extend across at least a gap between outer portions of the two or more expandable chambers in the second activated state.

[0038] Those skilled in the art to which this application relates will appreciate that other and further additions, deletions, substitutions and modifications may be made to the described embodiments.