The present disclosure relates generally to downhole tools for positioning a tool string, and more specifically to a downhole tool for maintaining the position of a tool string within a wellbore.
In drilling an oil well, a variety of operations may be carried out on a wellbore. For certain operations, the accurate positioning of a tool within the well may be critical. As an example, operations such as acidizing, fracturing, flow testing, washing perforations or pressure testing may specifically target a certain section of wellbore. In these operations, the targeted section of wellbore may be isolated from the wellbore areas both above and below. For these operations, a “straddle packer” assembly may be utilized.
A straddle packer may include inflatable packers positioned on either side of the wellbore section to be treated. Connecting the packers is a tubular member which may include at least one selectively openable port. In order to effectively treat the section of wellbore, positioning of the straddle packer is very important, as the targeted section of wellbore must be between the upper and lower packers so that the ported tubular may act thereon. While the packers are inflated, until contact is made with the wellbore, the straddle packer assembly may move undesirably within the wellbore. Additionally, to ensure the straddle packer assembly remains in position, a portion of the contact area between each packer and the wellbore is typically made up of metal slats. The slats, though effective in preventing movement of the packer, are not as effective in sealing against the wellbore as the flexible outer bladder of the packer.
The present disclosure provides for a downhole tool for use within a wellbore. The downhole tool may include a hydraulic anchor. The hydraulic anchor may include a tool body. The tool body may include a generally cylindrical mandrel, the mandrel having an interior. The tool body may also include a coupler positioned to allow the tool body to couple to a tubular member. The hydraulic anchor may also include a stroking sleeve. The stroking sleeve may be generally tubular, and may be positioned to slide along the mandrel of the tool body. The hydraulic anchor may also include an actuation cylinder, the actuation cylinder formed between the stroking sleeve and the tool body. The actuation cylinder may be fluidly coupled to the interior of the mandrel. The hydraulic anchor may also include an extendible arm. The extendible arm may include a grip plate, a first extension linkage, and a second extension linkage. The first extension linkage may be pivotably coupled between the tool body and the grip plate. The second extension linkage may be pivotably coupled between the grip plate and the stroking sleeve. The downhole tool may also include an inflatable packer. The inflatable packer may include a packer mandrel, the packer mandrel having an interior. The inflatable packer may also include a packer bladder, the packer bladder being generally tubular in shape and positioned about the packer mandrel. The inflatable packer may also include a packer inflation port, the packer inflation port formed in the packer mandrel and positioned to couple the interior of the packer mandrel with the annular space between the packer mandrel and the packer bladder.
The present disclosure also provides for a downhole tool for use within a wellbore. The downhole tool may include a hydraulic anchor. The hydraulic anchor may include a tool body, the tool body including a generally cylindrical mandrel having an interior. The tool body may include a coupler positioned to allow the tool body to couple to a tubular member. The hydraulic anchor may also include a stroking sleeve, the stroking sleeve being generally tubular and positioned to slide along the mandrel of the tool body. The hydraulic anchor may also include an actuation cylinder formed between the stroking sleeve and the tool body. The actuation cylinder may be fluidly coupled to the interior of the mandrel. The hydraulic anchor may also include an extendible arm. The extendible arm may include a grip plate, a first extension linkage, and a second extension linkage. The first extension linkage may be pivotably coupled between the tool body and the grip plate. The second extension linkage may be pivotably coupled between the grip plate and the stroking sleeve. The downhole tool may also include a swellable packer. The swellable packer may include a packer mandrel, the packer mandrel having an interior. The packer mandrel may be coupled to the tool body. The swellable packer may also include an elastomeric swellable body, the elastomeric swellable body being generally tubular in shape and positioned about the packer mandrel.
The present disclosure also provides for a method. The method may include positioning a tool string within a wellbore. The tool string may include a hydraulic anchor. The hydraulic anchor may include a tool body, the tool body including a generally cylindrical mandrel having an interior. The tool body may include a coupler positioned to allow the tool body to couple to a tubular member. The hydraulic anchor may also include a stroking sleeve being generally tubular and positioned to slide along the mandrel of the tool body. The hydraulic anchor may also include an actuation cylinder formed between the stroking sleeve and the tool body. The actuation cylinder may be fluidly coupled to the interior of the mandrel. The hydraulic anchor may also include an extendible arm. The extendible arm may include a grip plate, a first extension linkage, and a second extension linkage. The first extension linkage may be pivotably coupled between the tool body and the grip plate. The second extension linkage may be pivotably coupled between the grip plate and the stroking sleeve. The tool string may also include a swellable packer. The swellable packer may include a packer mandrel having an interior. The packer mandrel may be coupled to the tool body. The swellable packer may include an elastomeric swellable body, the elastomeric swellable body being generally tubular in shape and positioned about the packer mandrel. The method may further include applying fluid pressure to the actuation cylinder. The method may further include extending the extendible arm, the extendible arm contacting the surrounding wellbore. The method may further include exposing the elastomeric swellable body to a swelling fluid, the elastomeric swellable body increasing in volume to form a seal between the packer mandrel and the wellbore.
The present disclosure also provides for a method. The method may include positioning a tool string within a wellbore. The tool string may include a hydraulic anchor. The hydraulic anchor may include a tool body, the tool body including a generally cylindrical mandrel having an interior. The tool body may include a coupler positioned to allow the tool body to couple to a tubular member. The hydraulic anchor may also include a stroking sleeve being generally tubular and positioned to slide along the mandrel of the tool body. The hydraulic anchor may also include an actuation cylinder formed between the stroking sleeve and the tool body. The actuation cylinder may be fluidly coupled to the interior of the mandrel. The hydraulic anchor may also include an extendible arm. The extendible arm may include a grip plate, a first extension linkage, and a second extension linkage. The first extension linkage may be pivotably coupled between the tool body and the grip plate. The second extension linkage may be pivotably coupled between the grip plate and the stroking sleeve. The tool string may also include an inflatable packer. The inflatable packer may include a packer mandrel, the packer mandrel having an interior. The inflatable packer may include a packer bladder, the packer bladder being generally tubular in shape and positioned about the packer mandrel. The inflatable packer may include a packer inflation port formed in the packer mandrel and positioned to couple the interior of the packer mandrel with the annular space between the packer mandrel and the packer bladder. The method may also include applying fluid pressure to the actuation cylinder, and extending the extendible arm, the extendible arm contacting the surrounding wellbore. The method may also include applying fluid pressure to the packer inflation port, inflating the inflatable packer.
The present disclosure also provides for a downhole tool on a tool string having a tool string bore positionable in a wellbore having a wellbore axis. The downhole tool may include a first packer sub coupled to the tool string, the packer sub having a first inflatable element and a first packer inflation port. The downhole tool may also include a valve sub coupled to the tool string. The valve sub may include a valve sub housing, the valve sub housing being generally tubular having at least one packer supply port in fluid communication with the packer inflation port. The valve sub may further include a control tube, the control tube being generally tubular and aligned with the valve sub housing and having an upper and lower end, the upper end coupled to the tool string, and the lower end positioned within the bore of the valve sub housing. The control tube may have a bore and at least one aperture through its side wall. The control tube may have an open position in which the aperture provides fluid communication between the bore of the control tube and the packer supply port and a closed position in which the apertures are covered by the inner wall of the valve sub housing and the bore of the control tube. The control tube bore may be in fluid communication with the tool string bore. The valve sub may further include a shift sleeve coupled to the lower end of the control tube having a hole adapted to accept an axle pin. The valve sub may further include a rotatable ball adapted to rotate about the axle pin. The rotatable ball may have at least one flow path through its body. The rotatable ball may have an open position and a closed position selected by the upward or downward movement of the tool string. The open and closed positions of the rotatable ball may be in opposition to the open and closed position of the control tube, thereby allowing or preventing fluid flow through the at least one flow path from the tool string bore and the bore of the control tube. The rotatable ball may have a rotation pin extending from its outer surface. The valve sub may include a rotation pin sleeve coupled to the rotation pin and adapted to rotate the ball from the closed position to the open position in response to a movement of the ball toward or away from the rotation pin sleeve. The downhole tool may also include a hydraulic anchor. The hydraulic anchor may include a tool body, the tool body including a generally cylindrical mandrel having an interior. The tool body may include a coupler positioned to allow the tool body to couple to a tubular member. The hydraulic anchor may also include a stroking sleeve being generally tubular and positioned to slide along the mandrel of the tool body. The hydraulic anchor may also include an actuation cylinder formed between the stroking sleeve and the tool body. The actuation cylinder may be fluidly coupled to the interior of the mandrel. The hydraulic anchor may also include an extendible arm. The extendible arm may include a grip plate, a first extension linkage, and a second extension linkage. The first extension linkage may be pivotably coupled between the tool body and the grip plate. The second extension linkage may be pivotably coupled between the grip plate and the stroking sleeve.
The present disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
As depicted in
Inflatable packer assembly 151, as understood in the art, may include tubular member 153, upper and lower housings 155, 157, and packer bladder 159. In some embodiments, inflatable packer assembly 151 relies on hydraulic anchor 101 to prevent movement within the wellbore and thus may include no external slats.
As depicted in
In some embodiments, tool body 103 may further include mandrel 119. Mandrel 119 may be generally cylindrical so that stroking sleeve 105 may slide along mandrel 119 in response to hydraulic pressure introduced into actuation cylinder 121. In some embodiments, actuation cylinder 121 may be formed in a space between mandrel 119 and lower extension 123 of stroking sleeve 105. In some embodiments, as depicted in
Fluid may be supplied to actuation cylinder 121 via actuation port 125. In some embodiments, actuation port 125 may be formed through the interior of mandrel 119. Actuation port 125 may extend between the interior of tubular member 153 coupled to coupler 117 and actuation cylinder 121. As fluid pressure within actuation cylinder 121 increases, for example, as a result of an increase in fluid pressure within a tubular member 153, stroking sleeve 105 moves from the run-in position depicted in
Also in response to the increase in fluid pressure, fluid flows through packer actuation port 161 from the interior of tubular member 153. Packer actuation port 161 may be coupled to the interior 163 of packer bladder 159. As fluid pressure increases within the interior 163 of packer bladder 159, packer bladder 159 expands from the run-in position depicted in
When it is desired to move hydraulic anchor 101, pressure is bled from the interior of tubular member 153. Packer bladder 159 thus deflates into the interior of tubular member 153. Likewise, pressure is bled from actuation cylinder 121. In some embodiments, spring 127 may be positioned to return stroking sleeve 105 to the run-in position. Spring 127 may be retained by piston 129 coupled to stroking sleeve 105. Spring 127 may, for example, assist stroking sleeve 105 to move back along mandrel 119. As the distance between tool body 103 and stroking sleeve 105 increases, extension linkages 113, 115 may cause grip plate 111 to move inward, away from the wall of the surrounding wellbore, thus releasing hydraulic anchor 101 from the wellbore.
In some embodiments, rupture disc 131 may be positioned in fluid communication with actuation cylinder 121 and the surrounding wellbore. Rupture disc 131 is positioned to release pressure within actuation cylinder 121 in the event that the differential pressure therebetween reaches a predetermined threshold value. The threshold value may be determined to, for example, prevent damage to either hydraulic anchor 101 or the surrounding wellbore. Additionally, if fluid becomes trapped in actuation cylinder 121 by, for example, a blockage in actuation port 125, a sufficiently strong pull on hydraulic anchor 101 from the attached tubular member may cause rupture disc 131 to rupture and release the pressure, allowing extension arms 109 of hydraulic anchor 101 to retract. As hydraulic anchor 101 is pulled upward within the wellbore, the resultant force of the wellbore may cause a downward movement of grip plate 111, which translates into a movement of stroking sleeve 105. This movement of stroking sleeve 105 may decrease the volume of actuation cylinder 121, thus causing an increase in pressure within actuation cylinder 121. Sufficient increase in pressure may thus cause rupture disc 131 to fail.
In some embodiments, as depicted in
In some embodiments, grip plate 111 may include a surface texture to, for example, increase resistance to the slipping of grip plate 111 along the surrounding wellbore. As depicted in
In some embodiments, one or more seals 135 may be positioned to, for example, retain fluid pressure within actuation cylinder 121. Seals 135 may be positioned between lower sub 107 and mandrel 119, mandrel 119 and stroking sleeve 105 (or any related component including spring retention nut 129 as shown), between components of stroking sleeve 105 (including between stroking sleeve 105, lower extension 123, or spring retention nut 129, and/or between lower extension 123 and lower sub 107).
In some embodiments, hydraulic anchor 101 may be designed such that hydraulic anchor 101 engages wellbore 5 before the inflatable packers begin to inflate. Likewise, hydraulic anchor 101 may be designed such that the inflatable packers fully deflate before hydraulic anchor 101 releases. Such a configuration may, for example, prevent damage to either wellbore 5 or inflatable packer 151 from movement of a partially inflated packer within the wellbore.
Although mandrel 119 is depicted as a solid member having actuation port 125 formed therein, one having ordinary skill in the art with the benefit of this disclosure will understand that mandrel 119 may instead be, for example, a tubular member. Actuation port 125 may, in such an embodiment, be formed within the wall of mandrel 119 or as an external control line. For example,
Actuation port 125 may, in some embodiments, be coupled to a valve assembly positioned in packer actuation port 161. Furthermore, although not depicted, mandrel 119 may include a second coupler positioned on the end opposite coupler 117 positioned to receive an additional tubular member, allowing the tool string to extend below hydraulic anchor 101.
String connection sub 20, as depicted in
Control tube 301, as illustrated, is a generally straight-walled cylindrical tube which extends axially downward from string connection sub 20. The lower end of control tube 301 fits into the bore of upper control housing 305. The bore of upper control housing 305 is generally cylindrical, and at its upper end has a diameter selected to allow a clearance or sliding fit with the outer wall of control tube 301. Outer wall of control tube 301 is fluidly sealed to the interior of upper control housing 305 by at least one seal 307, and is permitted to slide into and out of upper control housing 305 by upward or downward loading of the work string. In some embodiments, spring 309 may be included and configured to apply compressive force between piston 311 and the upper wall of upper control housing 305. Piston 311 is coupled to the outer wall of upstream connection housing 201 by, for example, a threaded connection. Spring 309 is illustrated as a coil spring axially disposed around control tube 301.
Control tube 301 may include, proximal to its lower end, at least one locking feature for preventing removal from upper control housing 305. Likewise, upper control housing 305 at its upper end may include a matching locking feature. For example,
Control tube 301 is coupled at its lower end to control tube extension 321 forming a fluidly sealed connection between the interior bore of control tube 301 and the interior bore of control tube extension 321, here depicted as including seal 323. Control tube extension 321 is a generally cylindrical, straight-walled tube extending downward along central axis 12, the bore of which fluidly connecting to and forming a continuation of valve sub bore 315.
Upper control housing 305 is coupled at its lower end to the upper end of lower control housing 325 forming a fluidly sealed connection between annular space 327 and at least one packer inflation port 329 formed in the body of lower control housing 325. Annular space 327 is defined as the cavity formed between the outer surface of control tube 301 and/or control tube extension 321 and the inner surface of upper control housing 305. Packer inflation port 329 continues through the rest of valve sub 30 to packer sub 40. Lower control housing 325 is a generally cylindrical tube having a smaller inner diameter than the inner diameter of the lower end of upper control housing 305, forming a lower interior flange 331. Lower interior flange 331 is positioned as a means to prevent over-insertion of control tube 301. When actuated, control tube 301 is forced downward into an “actuated position” by downward work string loading. Flanged groove 313 and J-pin 317 abut against upper surface 331, preventing any further movement. One of ordinary skill in the art will understand that this is only an exemplary configuration for preventing overinsertion, and other technically equivalent features may be employed without deviating from the scope of this disclosure. In this example, the axial distance between upper interior flange 319 and lower interior flange 331 defines stroke length A, the distance control tube 301 is allowed to traverse between the run-in position and the actuated position.
Referring to
Proximal to the upper end of control tube extension 321, a series of apertures 333 are positioned through the wall of control tube extension 321. Apertures 333 connect the bore of control tube extension 321 to the surrounding area. When control tube extension 321 is in the run-in position, as depicted in
The axial distance between lower interior flange 331 and topmost extent of apertures 333 defines a packer cut-off length B, which is the distance control tube extension 321 must traverse axially downward before the fluid connection between the bore and annular space 327 is severed.
Referring now to
Shift sleeve 339, may be a generally cylindrical tube extending axially downward, the bore of which fluidly connecting to and forming a continuation of valve sub bore 315. The lower end of shift sleeve 339 may include valve axle holes 347 along valve axle axis 14. Valve axle axis 14 is coincident and orthogonal to central axis 12. A portion of one side of the lower end of shift sleeve 339 is “cut away” along a plane parallel to central axis 12 and a plane parallel to valve axle axis 14. At the cut away portion, shift sleeve 339 is coupled to ball seat 349. Ball seat 349 is a generally cylindrical tube which fits within an inset of shift sleeve 339, the bore of which fluidly connecting to and forming a continuation of valve sub bore 315. One or more seals 351 may be used to ensure a fluid seal between ball seat 349 and shift sleeve 339.
The lower end of ball seat 349 is adapted to closely fit against the surface of rotatable ball 353. In at least one embodiment, the lower end of ball seat 349 is coupled to shift sleeve 339 so that ball seat 349 can move axially relative to rotatable ball 353 and shift sleeve 339 so that ball seat 349 forms sealing contact when fluid is pumped into the valve sub bore 315. One or more seals 355 may be used to ensure there is a sufficient seal between ball seat 349 and rotatable ball 353 to reliably divert fluid to inflate the packer elements with a prescribed volumetric flow rate. Rotatable ball 353 is generally spherical with valve bore 357 through its center. Rotatable ball 353 is rotatably coupled to shift sleeve 339 by valve axle pins 359, and may freely rotate about valve axle axis 14. Rotatable ball 353 is positioned to rotate approximately 90° when transitioned from its run-in position, shown in
Rotatable ball 353 in the actuated position abuts the upper edge of pressure tube 363 and forms a continuous fluid connection between valve sub bore 315 and valve output bore 361. The top surface of pressure tube 363 forms a lower valve seat which is adapted to closely fit the surface of rotatable ball 353.
Rotatable ball 353 is actuated by rotation pin sleeve 365. Shift sleeve 339, rotatable ball 353, and rotation pin sleeve 365 are shown in detail in
In the run-in configuration of
C=w−drotation pin
where w is the axial length of rotation window 369, and drotation pin is the diameter of rotation pin 367.
Rotation pin 367 is positioned a selected distance from valve axle axis 14, defining a rotation pin eccentricity length D. Rotation pin 367 is positioned along a line extending 45 degrees from central axis 12. Eccentricity length D is selected such that rotatable ball 353 is rotated approximately 90° when shift sleeve 339 is moved stroke length A with a ball seal retention length C.
Once shift sleeve 339 and rotatable ball 353 have moved ball seal retention length C, rotation pin 367 contacts the wall of rotation window 369. As shift sleeve 339 continues to move, rotatable ball 353 is rotated about valve axle axis 14 by the resultant force applied by rotation pin sleeve 365 on rotation pin 367 through the wall of rotation window 369. As rotatable ball 353 rotates, valve bore 357 begins to open fluid communication between valve sub bore 315 and valve bore 357, and subsequently valve output bore 361. Ball seal retention length C is selected such that it is greater than packer cut-off length B in order to prevent fluid communication between valve sub bore 315 and valve bore 357 until after apertures 333 have seated within lower control housing 325. Once shift sleeve 339 and rotatable ball 353 have moved stroke length A, valve bore 357 is aligned with central axis 12, thereby allowing fluid continuous flow between valve sub bore 315 and valve output bore 361.
Likewise, as shift sleeve 339 and rotatable ball 353 are moved axially upward, rotation pin 367 contacts the other wall of rotation window 369. As shift sleeve 339 and rotatable ball 353 continue to move upward, the resultant force causes rotatable ball 353 to rotate back approximately 90°, thereby isolating valve sub bore 315 from valve output bore 361 and returning to its run-in configuration. Geometry of rotation window 369 is selected such that rotatable ball 353 remains at least partially open when apertures 333 are opened to annular space 327.
Referring back to
Lower end of lower control housing 325 is coupled to the upper end of crossover housing 373. Crossover housing 373 may include at least one port formed in its wall to form a continuation of packer inflation port 329. Crossover housing 373 is a generally cylindrical tube extending downward along central axis 12. Crossover housing 373 is depicted as threadedly coupled to control housing 325. Pressure tube 363 is coupled within the upper bore of crossover housing 373. Continuing to
Upper packer sub 40 is a generally cylindrical tube, including upper packer mandrel 401 having upper packer bore 403 fluidly connected to valve output bore 361. Upper packer sub 40 is configured to allow fluid to flow from packer inflation port 329 to the interior of upper packer 405. Upper packer sub 40 may include upper ring 407 which is threadedly connected to downwardly and inwardly tapered member 409, thereby compressively sealing the end of upper packer 405 against the interior of upper packer housing 411. Holes in upper ring 407 pass fluid from packer inflation port 329 to the interior of upper packer 405. Upper packer 405 may include upper packer inner layer 413 and upper packer outer layer 415, both depicted as elastomeric material, and an upper and lower metal packer shield 417, 419. Upper and lower metal packer shields 417, 419 may be configured to control the inflation of upper packer 405.
Continuing to
Hose 501 is shown continuing downward through the well bore, having various fittings and configurations to, for example, secure additional lengths of hose, couple hose 501 to fracing mandrel 503, allow strain relief, etc. One of ordinary skill in the art will readily understand that the configuration shown in the figures is meant only as an example, and any reconfiguration would not deviate from the scope of this disclosure.
Fracing mandrel 503 couples, at its lower end, to upper end of lower packer sub 60, here shown as threadedly connected to lower packer top housing 627. Lower packer top housing 627 may include lower packer bore 603 fluidly connected to fracing sub bore 505. Lower packer top housing 627 is coupled at its lower end to the upper end of lower packer mandrel 601, the bore of which fluidly connected to and forming an extension of lower packer bore 603.
Lower packer top housing 627 may also include lower packer hose connector 629 which is coupled to hose 501 and allows fluid to pass from hose 501 to lower packer sub 60, thereby connecting upper packer sub 40 to lower packer sub 60. Fluid from hose 501 can pass through at least one inflation port 631 to the interior of lower packer 605.
Referring to
Lower end of lower packer mandrel 601 is coupled to hydraulic anchor 701. Hydraulic anchor 701 is positioned to be actuated by control hose 725 coupled to lower packer control hose connector 637. Control hose 725 is coupled to actuation cylinder 721. Thus, once valve sub 30 is actuated, upper packer sub 40, lower packer sub 60, and hydraulic anchor 701 are all actuated by the same fluid pressure. In some embodiments, hydraulic anchor 701 may provide anchoring between straddle packer assembly 10 and the surrounding wellbore or tubular to, for example, allow force applied by the tool string to press down against control tube 301. Additionally, hydraulic anchor 701 may include mandrel 719 which, in such an embodiment, may be a tubular member having no apertures. In some embodiments, hydraulic anchor 701 may include a lower connector 741 allowing, for example, the connection of a tubular member below hydraulic anchor 701.
In other embodiments, as depicted in
In operation, swellable packer 851 and hydraulic anchor 801 are positioned in the wellbore. As previously discussed, fluid pressure actuates hydraulic anchor 801, holding swellable packer 851 in position within the wellbore during the time it takes for swellable packer 851 to fully expand and create the seal. In some embodiments, a valve (not shown) may be positioned within mechanical anchor 801 to cause mechanical anchor 801 to permanently remain in the engaged position once pressure inside actuation port 825 is bled. In some embodiments, a mechanical retainer (not shown) may be positioned within actuation cylinder to retain mechanical anchor 801 in the engaged position with extendible arm 809 in the extended position once extended. One having ordinary skill in the art with the benefit of this disclosure will understand that any such mechanical retainer mechanism may be used, including without limitation, a spring-loaded pawl, ratchet system, etc. may be utilized without deviating from the scope of this disclosure. With mechanical anchor 801 retained in the open position, the tool string used to position swellable packer 851 within the wellbore may thus be removed, leaving swellable packer 851 within the wellbore while it expands and, for example, to seal against the wellbore.
The foregoing outlines features of several embodiments so that a person of ordinary skill in the art may better understand the aspects of the present disclosure. Such features may be replaced by any one of numerous equivalent alternatives, only some of which are disclosed herein. One of ordinary skill in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. One of ordinary skill in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure.
This application is a non-provisional application which claims priority from U.S. provisional application No. 61/837,876, filed Jun. 21, 2013, the entirety of which is hereby incorporated by reference; and from U.S. provisional application No. 61/926,571, filed Jan. 13, 2014, the entirety of which is hereby incorporated by reference.
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