Title:
APPARATUS AND METHOD FOR WELLBORE ISOLATION
Kind Code:
A1


Abstract:
An apparatus for isolating a selected leg of a wellbore from the remainder of the wellbore includes a packer positionable in the selected leg of the wellbore, a tube extending through the packer from an uphole side of the packer to a downhole side of the packer to permit a fluid flow communication to the selected leg of the wellbore past the packer and a valve positioned in the tube to control fluid flow through the tube. In a method for isolating a selected leg of a wellbore, the apparatus is positioned in the selected wellbore leg and the packer set to permit fluid flow communication past the apparatus only through the tube and the valve of the apparatus.



Inventors:
Themig, Daniel Jon (Cochrane, CA)
Application Number:
12/249602
Publication Date:
03/19/2009
Filing Date:
10/10/2008
Assignee:
PACKERS PLUS ENERGY SERVICES INC. (Calgary, CA)
Primary Class:
International Classes:
E21B33/12
View Patent Images:



Primary Examiner:
BAGNELL, DAVID J
Attorney, Agent or Firm:
OBLON, MCCLELLAND, MAIER & NEUSTADT, L.L.P. (ALEXANDRIA, VA, US)
Claims:
1. A method for isolating a selected open hole wellbore leg from the remainder of the wellbore, the method comprising: providing an apparatus including a packer, slips in association with the packer, a tube extending through the packer from an uphole side of the packer to a downhole side of the packer and a valve positioned in the tube to control fluid flow through the tube; positioning the apparatus in the selected open hole wellbore leg such that the packer and the valve of the apparatus is positioned within the selected open hole wellbore leg such that the tube permits a fluid flow communication to the selected open hole wellbore leg of the wellbore past the packer as controlled by the valve; and expanding the slips and the packer to engage the wall of the selected open hole wellbore leg and to seal between the tube and the wall of the selected open hole wellbore leg.

2. The method of claim 1 further comprising positioning the apparatus in the selected open hole wellbore leg such that the tube is within the selected open hole wellbore leg.

3. The method of claim 1 further comprising opening the valve to permit fluid flow communication with the selected open hole wellbore leg.

4. The method of claim 1 further comprising introducing wellbore treatment fluids through the valve into the selected open hole wellbore leg.

5. The method of claim 1 further comprising deploying a tubing string from surface, connecting the tubing string to the tube of the apparatus and pumping wellbore treatment fluids down the tubing string and through the tube of the apparatus into the selected open hole wellbore leg.

6. The method of claim 5 further comprising manipulating the tubing string to open the valve of the apparatus.

7. The method of claim 1 wherein the packer is a solid body packer.

8. The method of claim 1 wherein in the step of expanding the slips, whickers on the slips are driven to bite into the wellbore wall.

9. A method for isolating a selected wellbore leg from the remainder of the wellbore, the method comprising: providing an apparatus including a packer, a tube extending through the packer from an uphole side of the packer to a downhole side of the packer; positioning the apparatus in the selected wellbore leg downhole of a wellbore junction where the selected wellbore leg extends from the remainder of the wellbore, the packer and the tube of the apparatus being positioned within the selected wellbore leg; expanding the packer to engage the wall of the selected wellbore leg and to create a seal between the tube and the wall of the selected wellbore leg, wherein the apparatus is operable to isolate fluid flow communication with the selected wellbore leg of the wellbore past the packer except through the tube and access remains unimpeded to the remainder of the wellbore.

10. The method of claim 9 further comprising, while the apparatus remains in the selected wellbore leg, accessing a second selected wellbore leg downhole of the wellbore junction.

11. The method of claim 9 further comprising positioning the apparatus in the selected wellbore leg such that an uphole end of the tube is within the selected wellbore leg.

12. The method of claim 9 wherein the selected wellbore leg is an open hole region.

13. The method of claim 9 further comprising introducing wellbore treatment fluids through the tube into the selected wellbore leg.

14. The method of claim 9 wherein the tube includes a valve therein to control fluid flow through the tube and the method further comprises opening the valve to permit fluid flow communication with the selected wellbore leg.

15. The method of claim 14 wherein the valve of the apparatus is selected to permit one way fluid flow into the selected wellbore leg such that the wellbore treatment fluids are isolated in the selected wellbore leg.

16. The method of claim 9 further comprising deploying a tubing string from surface, connecting the tubing string to the tube of the apparatus and pumping wellbore treatment fluids down the tubing string and through the tube of the apparatus into the selected wellbore leg.

17. The method of claim 9 wherein the packer is a solid body packer.

18. The method of claim 9 wherein the apparatus further includes slips in association with the packer and the method further comprises expanding the slips into engagement with the wall of the selected wellbore leg.

19. The method of claim 18 wherein expanding the slips includes driving whickers on the slips to bite into the wall of the selected wellbore leg.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part application of U.S. application Ser. No. 12/039,150, filed Feb. 28, 2008, which is presently pending and which is a continuation application of U.S. application Ser. No. 11/315,494 filed Dec. 23, 2005, now U.S. Pat. No. 7,353,878, which is a continuation application of U.S. application Ser. No. 10/604,811 filed Aug. 19, 2003, now U.S. Pat. No. 7,021,384, issued Apr. 4, 2006. The previous US formal patent applications and the present application all claim priority from U.S. provisional patent application 60/404,783 filed Aug. 21, 2002.

FIELD

An apparatus and a method for wellbore isolation are taught and, in particular, the invention relates to an apparatus and a method for isolating, with controlled access, a lateral wellbore from the remainder of the wellbore.

BACKGROUND

A well may be drilled with multiple legs or laterals that may be vertical, inclined or horizontal, deviated, straight or otherwise. When junctions to the legs are created, isolating one or more legs from the remainder of the wellbore can be especially important to protect the isolated leg or legs from other drilling operations including fluids and debris, to provide the ability to stimulate wellbore legs individually and/or to control fluid flow from the lateral wellbore.

SUMMARY

An apparatus for wellbore isolation has been invented that permits isolation of a selected wellbore from the remainder of the well. The apparatus is mountable in the selected lateral wellbore, so as not to impede access to non-isolated portions of the well.

Thus, in one aspect of the present invention, there is provided an apparatus for isolating a selected leg of a wellbore from the remainder of the wellbore: comprising a packer positionable in the selected leg of the wellbore, a tube extending through the packer from an uphole side of the packer to a downhole side of the packer to permit a fluid flow communication to the selected leg of the wellbore past the packer and a valve positioned in the tube to control fluid flow through the tube.

The apparatus isolates the selected wellbore leg from the remainder of the wellbore, but the provision of a valve permits controlled access to and/or flow from the selected wellbore leg. The selected wellbore leg can vary between a vertical and a horizontal orientation, be open hole or lined, straight or deviated, etc.

The tube can be a mandrel of the packer or another section of tubing installed to extend though the packer. The tube can be connected to a tubing string on the downhole side of the packer, which extends into the selected wellbore leg. The tubing string can be selected to act against wellbore cave in or can be configured to permit wellbore stimulation procedures such as fracturing, sprinkling, cleaning, etc. In one embodiment, the tube, at its uphole end, includes a portion for accepting a tool from surface such as, for example, an end of a tubing string, a seal, and a valve or packer actuator tool. In addition to fluid flow, the tube can permit passage of tools therethrough, if desired.

The valve is selected, when closed, to substantially seal against fluid flow therethrough and, thereby through the tube and through the wellbore past the packer. The valve can be selected to permit one-way or two-way fluid flow control. The valve can, for example, be a check valve or an actuable valve. In one embodiment, the valve is openable by actuation from surface by use, for example, of a tubing string or line conveyed actuator. The valve can be positioned anywhere along the tube to control fluid flow through the tube between its uphole end and its downhole end. In addition to fluid flow, the valve can be selected to permit passage of tools through the tube.

The packer acts to seal fluid flow communication to and from the wellbore except through the tube and valve. The packer can also assist in anchoring the apparatus in the selected wellbore. The packer can be of any type, capable of creating a substantial seal between the tube and the wall of the selected wellbore leg. The packer can be selected, as will be appreciated, based on wellbore conditions, desired permanency of the seal, wellbore wall parameters, etc. In one embodiment, which is particularly beneficial in open hole conditions, the packer is a solid body packer. A solid body packer creates a seal between the tube and the borehole wall, be it lined or open hole, using a packing element, which is mechanically extruded by either mechanically or hydraulically applied force. The solid body packers provide high pressure sealing in open holes and can be equipped with multiple packing elements that will load into each other to provide additional pack-off.

The apparatus can include stabilizers for anchoring the packer in the wellbore, as may be required where there is a considerable pressure differential about the packer. The apparatus can include slips selected to engage the borehole wall. These slips can, for example, be mounted in association with the packer or the tube. Another stabilizer can include a the back to the borehole from which the selected wellbore leg extends.

With reference to the foregoing, in another broad aspect of the present invention, there is provided a method for isolating a selected wellbore leg from the remainder of the wellbore, the method comprising: providing an apparatus according to one of the embodiments of the present invention; positioning the apparatus in the selected wellbore leg such that the valve of the apparatus is positioned within the selected wellbore leg; and expanding the packer to seal between the tube and the wall of the selected wellbore.

In one embodiment, the method includes positioning the apparatus in the selected wellbore leg such that the tube of the apparatus and preferably the uphole end of the tube is within the selected wellbore leg. The method can include anchoring the apparatus in the selected wellbore leg.

In the method, the valve of the apparatus can be opened to permit fluid flow communication with the selected wellbore leg. Fluid flow communication can be for introduction of cleaning, completion or stimulation fluids, production therefrom, etc. For example, the method can include deploying a tubing string from surface, connecting the tubing string to the tube of the apparatus and pumping wellbore treatment fluids down the tubing string and through the tube of the apparatus into the selected lateral. The tubing string can include an actuator for opening the valve of the apparatus and the method can include manipulating the tubing string to open the valve of the apparatus.

In the method, the apparatus can be left in the well for continued or future isolation. Alternately, the valve of the apparatus can be removed or the entire apparatus can be removed once it is no longer desired to isolate the selected wellbore.

It is to be understood that other aspects of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein various embodiments of the invention are shown and described by way of illustration. As will be realized, the invention is capable for other and different embodiments and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. Accordingly the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.

DESCRIPTION OF THE DRAWINGS

Drawings are included for the purpose of illustrating certain aspects of the invention. Such drawings and the description thereof are intended to facilitate understanding and should not be considered limiting of the invention. Drawings are included, in which:

FIG. 1 is a schematic view through a wellbore having multiple legs and having installed in each of the legs an apparatus according to the present invention.

FIG. 2 is a side elevation of a wellbore isolation apparatus included in an assembly for use downhole including a running string aligned for connection of the apparatus uphole end and a wellbore liner string connected on the apparatus downhole end.

FIGS. 3A to 3E are sections through a wellbore having multiple legs and illustrating schematically a process for wellbore isolation.

DESCRIPTION OF VARIOUS EMBODIMENTS

The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments contemplated by the inventor. The detailed description includes specific details for the purpose of providing a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.

Referring to FIG. 1, there is shown a sectional view through a wellbore including multiple lateral wellbore legs 10, 12 extending from a junction 14. A borehole 16 extending uphole from the junction and is connected to surface.

Legs 10, 12 each have disposed therein an apparatus 18a, 18b for isolating, with controlled communication therewith, each of the legs from the remainder of the wellbore. Leg 10 is lined with a liner or casing 20, while leg 12 is open hole.

Apparatus 18a illustrates one embodiment of the invention and includes a packer 22a positioned in the leg of the wellbore, a tube 24a extending through the packer from an uphole end 24a′ on an uphole side of packer 22a to a downhole end 24a″ on a downhole side of the packer. Tube 24a permits a fluid flow communication between the borehole 16 and leg 10 past the packer. The apparatus further includes a valve 26a positioned in the tube to control fluid flow through the tube and anchoring slips 28 in association with the packer. The slips include whickers that bite into the material of the liner to stabilize the packer in the wellbore leg.

Apparatus 18a, and in particular, valve 26a and packer 22a, prevents debris and fluids from the remainder of the wellbore from passing into wellbore leg 10. However, the valve is openable, as by a check arrangement such as a ball valve or flapper valve, to permit one-way fluid flow, such as of produced fluids, from the leg 10 to borehole 16 through the tube. The valve can include a pressure control, which operates to permit fluid only at pressures exceeding a selected pressure to open the valve.

Apparatus 18b also includes a packer 22b positioned in the leg of the wellbore, a tube 24b extending through the packer from an uphole end 24b′ to a downhole end 24b″ to permit a fluid flow communication between the borehole 16 and leg 12 past the packer and a valve 26b positioned in the tube to control fluid flow through the tube. Apparatus 18b is positioned close adjacent junction 14. However, it could be spaced back a distance from the wellbore junction, if desired.

Apparatus 18b isolates wellbore leg 12 from the remainder of the wellbore for the purpose of selective injection of wellbore treatment fluids into the leg for the purpose, for example, of wellbore stimulation. As such, tube 24b at its downhole end is connected into a tubing string 30 for conveying stimulation fluids to selected intervals of the leg. Tubing string 30 includes a plurality of packers 32 (only one can be seen in the drawing) thereabout which divide the leg into a plurality of treatment segments. The tubing string can include ports 34 opened by sleeves 36 (only one can be seen) operable by fluid pressure created by the seating therein of a sealing device, such as a ball. As such, valve 26b is selected to permit passage of the sealing devices used to actuate sleeves 36. Tubing strings similar to tubing string 30 and methods for using those tubing strings for stimulation of a formation are described in detail in applicant's corresponding application US 2003/0127227, published in July, 2003.

Packer 22b is a solid body open hole packer such as is available from the assignee of this application. Valve 26b is a one-way check valve, for example of the flapper type, that can be opened to permit fluid flow through the tube from its uphole end 24b′ to its downhole end 24b″, but not in the reverse. The valve is actuable to be opened by pressures exceeding its flapper force. Valve 26b is opened for example by pumping of fluids therethrough at normal treatment pressures. Treatment fluids can be pumped through a tubing string 38, such as coiled tubing, which is connectable to uphole end 24b′ of the tube. Uphole end 24b′ can be formed as by provision of locking dogs, seals, polishing, collets, etc. to accept and retain the end of the tubing string 38 so that it is secured during wellbore treatment through apparatus 18b. If desired, the valve of the apparatus can be formed to cooperate with tubing string or a part connected thereto such that the valve is openable by connection of a tubing string, or other member conveyed from surface, to the apparatus.

Packers 32 act to anchor the tubing string and apparatus 18b against the pressure differentials that are created during wellbore treatment.

In use to isolate a wellbore leg from the remainder of the wellbore, the apparatus such as that identified as 18a or 18b, is positioned in the selected wellbore leg such that the uphole end of the tube is positioned within the selected wellbore leg and open to the wellbore above the packer. The packer is then expanded to seal between the tube and the wall, which can be open hole or lined, of the selected wellbore leg. If stabilizers, such as slips 28 and/or additional packers 32 are used, they should also be set. The packer and valve of the apparatus act to substantially seal and, therefore, isolate the selected wellbore leg below the packer from the remainder of the well.

In one embodiment, the method includes opening the valve to permit fluid flow communication to the selected wellbore leg. Fluid flow communication can be for introduction of fluids such as, for example, cleaning, completion or stimulation fluids to the isolated leg or release of fluids, such as production fluids, from the wellbore leg, etc. The method can also include passing tools, such as sealing devices noted hereinbefore with respect to tubing string 30, through the valve of the apparatus.

To convey fluids to the apparatus, they can be pumped downhole such as through tubing string 38. Tubing string 38 can be operable to open the valve of the apparatus to permit pumping of fluid to the wellbore leg. Alternately or in addition, the valve can be pressure controlled, openable by pressures, which exceed a selected pressure.

In the method, the apparatus can be left in the well for continued or future isolation or removed once it is no longer needed. In one embodiment, the valve can be sheared out or opened to permit production through the apparatus.

With reference to FIG. 2 another apparatus 118 is shown for use to controllably isolate one portion of a wellbore from another portion thereof. Apparatus 118 illustrates one embodiment of the invention and includes a tube 124 extending through the packer from an uphole end, indicated at 124a to a downhole end, indicated at 124a. Tube 124 carries a packer including in this embodiment three packing elements 122 each annularly extending about tube 124. Packing elements 122 of the packer can be set to create a seal between the tube and any wall of a wellbore in which the apparatus is positioned.

The packer acts, when set, to seal fluid flow communication to and from any wellbore in which it is positioned except through the tube. The packer can also assist in anchoring the apparatus in a wellbore. The packer can be of any type, capable of creating a substantial seal between the tube and the wall of the selected wellbore leg. The packer can be selected, as will be appreciated, based on wellbore conditions, desired permanency of the seal, wellbore wall parameters, etc. In this illustrated embodiment, the packer is selected for use even in open hole conditions and is a solid body type packer wherein packing elements 122 are of the solid body, extrudable type. Two packing elements are mounted on a first packer body 123a and may be extruded out into a sealing position by either mechanically or hydraulically applied force, such as from a setting cylinder 125 positioned therebetween. The dual packing elements on packer body 123a can load into each other to provide additional pack-off.

The third packing element is carried on a second packer body 123b that also carries stabilizers, in the form of slips 128, for anchoring the packer in the wellbore. Slips 128 are positioned on second packer body 123b along with packing element 122 and can be set by a mechanism carried on the body. Slips 128 may be selected to engage the material of the borehole wall in which they are intended to be used. In the illustrated embodiment, slips 128 include whickers selected to bite into the material of the borehole wall. As such, apparatus 118 can be employed in installations a considerable pressure differential may be generated about the packer.

Tube 124 permits a fluid flow communication past the packer, when the packer is set. In addition to fluid flow, the tube can permit passage of tools therethrough, if desired. While tube 124 is referred to as the entire conduit passing through the packer, in the illustrated embodiment, tube 124 includes mandrels of packer bodies 123a, 123b and sections of tubing 124a, 124b, 124c connected at the opposite ends of the two packer bodies 123a, 123b and a section of tubing 124c between bodies 123a, 123b. As will be appreciated, downhole apparatus are often formed in this way including a plurality of tubular parts connected together by shear pins, threaded connections, etc.

Section of tubing 124a on the uphole side may include a portion for accepting connection of a string or tool from surface such as, for example, an end of a tubing string 119, a seal, a valve or packer actuator tool. Section of tubing 124a can include, for example, locking dogs, seals, polishing, collets, etc. to accept and releasably retain the end of the tubing string 119 so that it is secured during running into the hole and for wellbore treatment through apparatus 118. In the illustrated embodiment, section of tubing 124a defines an on-off tool stem for releasable connection to an on-off tool such as the overshot 139 illustrated on the end of tubing string 119.

Section of tubing 124c on the downhole side of the packer can have a free end or, as shown, can be connected to a tubing string 127, which can be run into a wellbore leg. Tubing string 127 can be selected to act against wellbore cave in or can be configured to permit wellbore stimulation procedures such as fracturing, sprinkling, cleaning, etc.

Apparatus 118 may further include a valve (not shown) in the tube to control fluid flow through the tube.

With reference to FIG. 3, further apparatus and methods for wellbore isolation are shown and described. For example, as shown, a wellbore may include multiple lateral wellbore legs such as an upper lateral 210 and a lower lateral 212 extending from a juncture, such as an open hole junction 214. The wellbore legs can vary between a vertical and a horizontal orientation, straight or deviated, be open hole or lined, etc. Although junction 214 and legs 210, 212 are shown in an open hole configuration, all or some of these wellbore intervals may be partially or fully lined by casing, liners, screens, cement, etc., shown for example in FIG. 1. Legs 210, 212 may be accessed through a wellbore 216 extending to surface. Although wellbore 216 is shown mostly lined by casing and cement 217, all or some of wellbore 216 may be partially or fully in an open hole or lined with other wellbore liners such as screen, etc.

In order to isolate a selected wellbore leg, such as leg 210, a wellbore isolation apparatus 218a, for example, according to one of the embodiments of the present invention is positioned in the selected wellbore leg and the packer elements 222a of the apparatus are expanded to seal between its tube 224a and the wall 213 of the selected wellbore leg. In the illustrated embodiment, apparatus 218a is positioned in upper lateral 210 by being conveyed from surface, as on a string 219a commonly called a tubing or work string.

When set in upper lateral 210, packer elements 222a of apparatus 218a operate to fluidly isolate, except as permitted through tube 224a, that portion 210a of the leg below the apparatus from the remainder of the wellbore including junction 214, leg 212 and wellbore 216. Tube 224a permits a fluid flow communication past the apparatus between portion 210a of the upper wellbore lateral and the remainder of the wellbore, past the seal of the packer.

To set the apparatus in the wellbore leg, packing elements 222a are positioned and expanded within the wellbore leg such that the packing elements seal between the wellbore wall and the tube. Additionally, slips 228a may be driven to engage the wall of the wellbore leg. Apparatus 218a is shown positioned close adjacent to junction 214, but can be spaced any distance from the junction, as desired. When set, apparatus 218a can be left in the well, for example if desired, with its uphole end 224a′ open and without continued connection to string 219, as shown in FIG. 3B.

In one embodiment, as illustrated apparatus 218a may be anchored, at least by its packing elements and slips, to be fully within selected leg 210 and even uphole end 224a of the tube may be positioned within the leg 210, such that when apparatus 218a is mounted in its selected lateral wellbore leg, access to non-isolated portions of the well may remain unimpeded. For example, as shown in FIG. 3C, while apparatus 218a remains in wellbore lateral leg 210, access can be made to another region of the well downhole of junction 214 such as, for example, to position and install, as by use of string 219b, another wellbore isolation apparatus 218b, this time in lower lateral leg 212.

Apparatus 218a, 218b each operate to allow fluid isolation of the wellbore legs in which they are each set (below their setting location) from the remainder of the well. Each apparatus may be mounted in its selected lateral wellbore, so as not to impede access to non-isolated portions of the well. For example, with reference to FIG. 3D, while both apparatus 218a, 218b remain installed in their respective wellbore legs, a tool 240 may be run in on a string 242, as by being guided through a tubing string 238a introduced from surface and connected to uphole end 224a′ of the tube. Tool 240 may be introduced through tube 224a, as shown in phantom, into the isolated portion 210a of the upper wellbore leg for operation to treat leg 210.

Another example is shown in FIG. 3E, wherein both apparatus 218a, 218b remain installed in their respective wellbore legs 210, 212 and a tubing string 238b is run in from surface past wellbore lateral 210 and junction 214 to connect to apparatus 218b. Apparatus 218b includes a valve in its tube 224b. The valve is selected, when closed, to substantially seal against fluid flow therethrough and, thereby through tube 224b and through the wellbore past the packer. The valve can be selected to permit one-way or two-way fluid flow control. The valve can, for example, be a check valve, a removable plug or an actuable valve. In one embodiment, the valve is openable by actuation from surface by use, for example, of tubing string 238b or line conveyed actuator. The valve can be positioned anywhere along the tube to control fluid flow through the tube between its uphole end and its downhole end.

In the illustrated method, the valve of the apparatus can be opened to permit fluid flow and/or tool communication with wellbore leg 212. The valve permits controlled communication with fluid and/or tools to and/or from the isolated wellbore leg therebelow. Fluid flow communication can be for introduction of cleaning, completion or stimulation fluids, or for production of fluids, from the wellbore leg. For example, the method can include deploying tubing string 238b from surface, connecting the tubing string to tube 224b of the apparatus and pumping, arrows F, wellbore treatment fluids down the tubing string and through the tube of the apparatus into lateral 212. The tubing string can include an actuator 244 for opening the valve of the apparatus and the method can include manipulating the tubing string and actuator to open the valve of the apparatus. The valve, being positioned in tube 224b, can be positioned in the wellbore leg. Apparatus 118b prevents debris and fluids from other regions of the wellbore from passing into wellbore leg 212 and allows any fluids introduced by the process to leg 212 to be isolated and held downhole of the apparatus, such that the isolated wellbore leg 212 can be selectively treated.

In the method, one or both apparatus 218a, 218b can be left in the well for continued or future isolation. Alternately, one or both apparatus 218a, 218b or the valve in apparatus 218b, can be removed when it is no longer necessary to isolate one or more of the selected wellbore legs.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to those embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the full scope consistent with the claims, wherein reference to an element in the singular, such as by use of the article “a” or “an” is not intended to mean “one and only one” unless specifically so stated, but rather “one or more”. All structural and functional equivalents to the elements of the various embodiments described throughout the disclosure that are know or later come to be known to those of ordinary skill in the art are intended to be encompassed by the elements of the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. For US patent properties, it is noted that no claim element is to be construed under the provisions of 35 USC 112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or “step for”.