Patent Publication Number: US-9845650-B2

Title: Running tool lock open device

Description:
BACKGROUND 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the presently described embodiments. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the described embodiments. Accordingly, it should be understood that these statements are to be read in this light and not as admissions of prior art. 
     When preparing a well for production, an open hole may be lined with pipes known as casings to stabilize the borehole and protect the borehole from contaminants. One or more pipes may be coupled, connected, or otherwise joined together to form a casing string. Although one casing string may be used, multiple casing strings may be run through a wellhead assembly and into a borehole using a device such as a running tool. 
     Running tools may be used in the oil and gas industry to run, set, retrieve, or otherwise position, equipment or other tools within a borehole. Running tools may include a traveling block, for example, or may refer to a variety of tools such as wireline tools, slickline tools, and coiled tubing tools, among many others. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a detailed description of the embodiments of the invention, reference will now be made to the accompanying drawings in which: 
         FIG. 1A  is an illustrative view of an oilfield in accordance with one or more embodiments of the present disclosure; 
         FIG. 1B  is a cross-sectional view of a wellhead in accordance with one or more embodiments of the present disclosure; 
         FIG. 1C  is a cross-sectional view of a seal assembly in accordance with one or more embodiments of the present disclosure; 
         FIGS. 2A-2E  are cross-sectional cut away views showing operation of a lock open device in accordance with one or more embodiments of the present disclosure; 
         FIGS. 3A-3F  are cross-sectional cut away views showing resetting of a lock open device in accordance with one or more embodiments of the present disclosure; 
         FIGS. 4A-4D  are cross-sectional side views showing collar profiles in accordance with one or more embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     One or more specific embodiments of the present disclosure will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, any use of any form of the terms “connect,” “engage,” “couple,” “attach,” “mate,” or any other term describing an interaction between elements is intended to mean either an indirect or a direct interaction between the elements described. In addition, as used herein, the terms “axial” and “axially” generally mean along or parallel to a central axis (e.g., central axis of a body or a port), while the terms “radial” and “radially” generally mean perpendicular to the central axis, and the term “rotational” generally means along a circumference, portion of a circumference, helical or other rotational path around the central axis. For instance, an axial distance refers to a distance measured along or parallel to the central axis, a radial distance means a distance measured perpendicular to the central axis, and a rotational distance means a distance measured along a path around the central axis. The use of “top,” “bottom,” “above,” “below,” “upper,” “lower,” “up,” “down,” “raise,” “lower,” “vertical,” “horizontal,” and variations of these terms is made for convenience, but does not require any particular orientation of the components. 
     Certain terms are used throughout the description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. 
     Referring now to  FIG. 1A , an illustrative oilfield environment is shown. A drilling platform  102  is equipped with a derrick  104  that supports a hoist  106  for raising and lowering a drill string  108 . The hoist  106  suspends a top drive  110  that rotates the drill string  108  as the drill string is lowered through the wellhead  112 . Sections of the drill string  108  are connected by threaded connectors  107 . Connected to the lower end of the drill string  108  is a drill bit  114 . As bit  114  rotates, a borehole  120  is created that passes through various formations  121  of the earth. A pump  116  may be used to circulate drilling fluid through a supply pipe  118  to top drive  110 , through the interior of drill string  108 , through orifices in drill bit  114 , back to the surface via the annulus around drill string  108 , and into a retention pit  124 . The drilling fluid transports cuttings from the borehole into the pit  124  and aids in maintaining the integrity of the borehole  120 . 
     Various other components may also be included in the drill string  108 . For example, in wells employing telemetry, downhole sensors or transducers (e.g., within resistivity logging or induction tool  126 ) may be coupled to a telemetry module  128  having a transmitter (e.g., acoustic telemetry transmitter) that may continuously or intermittently transmit telemetry signals or data (e.g., in the form of acoustic data or vibrations in the tubing wall of drill string  108 ). A receiver array  130  may be coupled to tubing below the top drive  110  to receive transmitted signals. One or more repeater modules  132  may be optionally provided along the drill string to receive and retransmit the telemetry signals. Of course other telemetry techniques can be employed within the scope of this disclosure including mud pulse telemetry, electromagnetic telemetry, and/or wired drill pipe telemetry, for example. Further, signals or data transmitted may be in any form known in the art, including without limitation electric or electro-magnetic signals or data. Many telemetry techniques also offer the ability to transfer commands from the surface to the tool, thereby enabling adjustment of the tool&#39;s configuration and operating parameters. In some embodiments, the telemetry module  128  also or alternatively stores measurements for later retrieval when the tool returns to the surface. 
     Referring now to  FIG. 1B , a cross-sectional view of a wellhead  112  in accordance with one or more embodiments is shown. At various times during the drilling process, the drill string  108  may be removed from the borehole and casing may be installed in the borehole  120  through wellhead  112 . Installation of a casing string may be completed by performing a number of processes. For example, installation of a casing string may include running the casing string into the borehole  120 , positioning the casing string within the borehole  120 , cementing the casing string in place by pumping cement through a bore of the casing string and along an outside of the casing string, and sealing the casing hanger. As will be appreciated, not all processes mentioned herein are needed for installing a casing string, and other processes may be performed in addition to or in the alternative to the above mentioned processes. 
     Although a single casing string may be installed within a borehole  120 , multiple casing strings may be used, as shown in  FIG. 1B . For example, when drilling a borehole  120 , a first section of the borehole  120  may be drilled using drill string  108 , and the drill string  108  may be pulled out of the borehole  120 . Thereafter, a casing string, such as conductor pipe  152  may be installed within the borehole  120 . The conductor pipe  152  may be the preliminary casing string run in a borehole  120  and may be connected to or integral with a conductor head  153 . After the conductor pipe  152  is installed, the drill string  108  may be used to further drill the borehole  120  until a particular depth is reached. The depth may depend on equipment limitations or may depend on the location of potential hydrocarbon reservoirs, among other factors. 
     After reaching the particular depth, the drill string  108  may then be pulled out of the borehole  120  and another casing string, such as surface casing  154 , may be installed in the borehole  120 . The surface casing  154  may be sealed against conductor head  153  using one or more seal assemblies  155 . The surface casing  154  may be connected to or integral with wellhead housing  157  in which casing hangers may be hung and sealed, as will be discussed below. 
     The drilling and installing process may be repeated for multiple casing strings. As will be appreciated, in one or more embodiments, each of the casing strings installed in the borehole  120  is of a different size, shape, and/or composition. For example, as shown in  FIG. 1B , intermediate casing strings  156 ,  158 , and  160  may be installed in the borehole  120  through the wellhead  112 . Conductor pipe  152  may be 30 inches in diameter, while surface casing  154  is 20 inches in diameter. Intermediate casings  156 ,  158 , and  160  may be 13⅜ inches in diameter, 9⅝ inches in diameter, and 7 inches in diameter, respectively. In other embodiments, casing strings installed within a borehole  120  may be of similar or varying size, shape, and/or composition, or any combinations of the foregoing. Other diameters for the casing strings may be considered without departing from the scope of the present disclosure. 
     To install casing, a casing string may be hung on a hanger and positioned within the borehole  120  using a running tool  150 . A running tool  150  may be connected to a drill string and may include a number of engagement points (not shown). The running tool  150  may also include other components used to run casing or other equipment into the borehole. As will be appreciated, the running tool  150  may be used to retrieve downhole tools or equipment, as is known in the art. 
     The running tool  150  may be configured to run a casing string, casing hanger, and seal assembly through the wellhead  112  and into a borehole  120 . In one or more embodiments, each casing string may be hung on a corresponding hanger and landed in at least one of the conductor head  153 , the wellhead housing  157 , or a previously installed casing hanger. For example, as shown in  FIG. 1B , the running tool  150  may engage with a casing hanger  162  and run casing string  160  into casing string  158 . The running tool  150  may be used to position casing string  160  within casing string  158  and land casing hanger  162  in casing hanger  164  attached to casing string  158 . In one or more embodiments, casing hanger  164  may be previously installed and landed within casing hanger  166  attached to intermediate casing string  156 . 
     Once the casing hanger  162  has landed within casing hanger  164 , cement may be pumped through a bore  168  of casing string  160  and around an annulus  170  between casing string  160  and casing string  158 . The cement is allowed to set, and a seal assembly  172  may be activated in order to seal annulus  174  between the casing hanger  162  and the wellhead housing  157 . As also shown, seal assemblies  176  and  178  may be located in the wellhead  112  and activated in order to seal against wellhead housing  157  and prevent leakage between casing hangers  164  and  166 . 
     Referring now to  FIG. 1C , a cross-sectional view of an example seal assembly in accordance with one or more embodiments is shown. In one or more embodiments, a seal assembly  180  may include a number of components designed to seal against a wellhead housing, such as wellhead housing  157  in  FIG. 1B , or other components in a borehole  120  or wellhead  112 . As shown, seal assembly  180  may include an upper seal  182 , a lower seal  184 , and a middle seal  186 , and may be used to seal between a casing hanger  188  and a wellhead housing  190 , for example and without limitation, by moving between an open position  192  and a sealed position  194 . As will be appreciated, the seal assembly  180  may be used to seal between any components known in the art. 
     To activate the seal assembly  180  a running tool, such as running tool  150  in  FIG. 1B , may be used to direct upper seal  182  toward lower seal  184  and form a seal as shown by sealed position  194 . In some embodiments, lower seal  184  may be directed toward upper seal  182  or both upper and lower seals  182  and  184  may be directed toward each other. Directing the seals may be performed by activating pistons in a running tool, casing hanger, or other downhole equipment to push one or more of the upper and lower seals  182  and  184  toward one another. In one or more embodiments, the running tool may include a mandrel  169  (as shown in  FIG. 1B ), which may be used to engage, position, and/or operate equipment (such as activating a seal assembly) in the borehole  120 . Those having ordinary skill in the art would appreciate that a number of other operations may be performed in order to move the seal assembly from an open position  192  to a sealed position  194 . Also as shown, optional sealing components may be placed within open portions  196  and  198 . 
     In one or more embodiments, a running tool may be configured to perform a number of operations in a particular order. For example, during well completion, a casing string may be run through a wellhead assembly at a surface end of a borehole using a running tool. The casing string may be hung from a casing hanger, and the casing hanger may be landed onto a wellhead or another previously installed casing hanger. Next, as described above, the casing string may be cemented into place within the borehole, and a seal assembly may then be set in order to seal an annulus between the wellhead assembly and the casing hanger. 
     In order to prevent a running tool from performing certain operations prematurely, a lock open device may be used. In one or more embodiments of the present disclosure, a lock open device may be used in combination with or separate from a running tool or may be included therein. In some embodiments, the lock open device may be integral or a part of the running tool. 
     Referring now to  FIG. 2A , a cross-sectional cut away view of a lock open device  200  is shown. The lock open device  200  includes a body  202  around and/or adjacent to a mandrel  204  of a running tool  206 . The device  200  may also include a collar  208  that may be attached, coupled, or otherwise connected to the mandrel  204 . For example, the collar  208  may be attached to the mandrel  204  using set screws (as shown) or any other form of connection known in the art. In such a configuration, rotation of the mandrel  204  causes the collar  208  to rotate as well. 
     The lock open device  200  also includes a can  210  having one or more pins  212  located thereon or connected thereto. Each of the one or more pins  212  may be configured to engage with a slot  207  formed within the collar  208 , as will be described in more detail below. The can  210  may be configured to allow a top plate  214  to be set thereon. 
     The top plate  214  may include one or more screws  216 , one or more cogs  218 , and one or more rods  220 . The screws  216  may be configured to displace (i.e., raise or lower) the top plate  214  from the can  210  or bias the top plate  214  down onto the can  210  using a biasing mechanism, such as biasing mechanism  222  for example. The top plate  214  may be displaced from the can  210  by rotating the screws  216  through corresponding threaded holes within the top plate  214 . The cogs  218  may extend from the top plate  214  and may be configured to engage with the collar  208 . As shown, the cogs  218  are formed integrally with the top plate  214 , but those having ordinary skill would appreciate that the cogs may be formed separate from the top plate  214  and connected or attached thereto. 
     Each of the rods  220  may be connected or attached to the top plate  214 . For example, the rods  220  may be screwed into top plate  214 . The rods  220  may extend through the can  210  and may engage with a biasing mechanism  222 . The biasing mechanism  222  may be housed within the can  210 , as shown. However, those having ordinary skill in the art would appreciate that the biasing mechanism  222  may be placed outside of the can  210 , along the can  210 , at the top plate  214 , or at any other location. The biasing mechanism  222  (e.g., a spring) may be configured to bias the top plate  214  onto the can  210  and may act as a resistance force when screws  216  displace the top plate  214  from the can  210 . The lock open device  200  may also include one or more dowel pins  224  to provide alignment (or other alignment or locating device known in the art), as will be described below. 
     Although the components of the lock open device  200  illustrated in  FIGS. 2A-2E  are arranged with respect to one another as shown, those having ordinary skill in the art would appreciate that other arrangements of the components may be considered without departing from the scope of the present disclosure. 
     Referring now to  FIGS. 4A-4D , side views of a collar profile  231  are shown in accordance with one or more embodiments of the present disclosure. As shown in  FIGS. 4A-4E , top plate  214  includes a cog  218 . Collar  208  may include a slot  207  having a rotational travel section  201  and an axial travel section  203 . The slot  207  may be configured to guide a pin, such as pin  212  of can  210 , along or within the rotational travel section  201  and/or along or within axial travel section  203 . 
     The collar profile  231  may be considered an open position profile in that the configuration of the profile  231  may enable the lock open device  200  to allow rotational movement of the collar  208  relative to the can  210 . The collar profile  231  also may be considered an anti-return profile if the configuration of the profile  231  enables the lock open device  200  to allow axial movement of the collar  208  relative to the can  210 , while restricting rotational movement of the collar  208  with respect to the can  210 . 
     In one or more embodiments, a profile  231  may be formed within a collar  208 . Although formed within collar  208 , as shown, one or more profiles may be formed within the collar  208 , can  210 , top plate  214 , and/or mandrel, among other components, without departing from the scope of the present disclosure. 
     Further, multiple profiles, possibly of different configurations, may be formed within a collar  208 . Indeed, a variety of different profile arrangements, shapes, and configurations may be considered without departing from the scope of the present disclosure. For example, profiles  231  are shown in  FIGS. 4A-4D  in an open position profile. In  FIG. 4A , an open position profile  231  of the arrangement and configuration illustrated in  FIGS. 2A-2E  is shown. The open position profile  231  may include a ramp  219  configured to engage with a cog  218 . The cog  218  may slide (or otherwise move) along ramp  219  and into anti-return slot  223 . Once positioned in anti-return slot  223 , rotation of the collar  208  may be restricted by engagement of the cog  218  with an edge  221  of anti-return slot  223  configured to mate with cog  218 . In this position (not shown in  FIG. 4A ), the lock open device may be considered to be in the anti-return profile. The cog  218  and/or the anti-return slot  223  may be configured to mate with each other such that once the cog  218  is positioned in the anti-return slot  223 , relative movement between the collar  208 , the can  210 , and the top plate  214  may be restricted and/or prevented. 
     Other examples of profiles  231  are shown in  FIGS. 4B-4D . For instance, as shown in  FIG. 4B , a cross section of cog  218  may include a circular or curved shape, or may be spherical, cylindrical, or any other shape known in the art. The cog  218  may be configured to mate with a curved edge  221  of anti-return slot  223 . As shown in  FIG. 4C , ramp  219  formed within collar  208  may have a curved shape and may be configured to engage with a curved shape of cog  218 . In addition, cog  218  may include an angled portion configured to mate or engage with edge  221  of anti-return slot  223 . In another example, as shown in  FIG. 4D , ramp  219  may include a number of steps  211 . The steps  211  may be formed at different angles relative to horizontal in order to provide varying resistance forces when cog  218  slides along ramp  219  and into engagement with anti-return slot  223 . As shown, cog  218  has an angled shape configured to engage with edge  221  of anti-return slot  223 . Those having ordinary skill in the art would appreciate that many open position profiles  231  exist that a cog  218  of a top plate  214  may engage with in order to allow or restrict relative movement between components. 
     Further, although the illustrative embodiments in  FIGS. 4A-4D  depict a single cog, a single slot, and a single anti-return slot, among other items, multiple cogs, slots, and/or anti-return slots, among other items may be used in accordance with one or more embodiments of the present disclosure. 
     Referring back to  FIGS. 2A-2E , each of the rods  220  may be connected to the top plate  214  and extend through the can  210 . A portion of each of the rods  220  may engage with a biasing mechanism  222  housed within the can  210 . 
     In one or more embodiments, the lock open device  200  may be set in an open position on a running tool  206  after a seal assembly (such as seal assembly  180  in  FIG. 1C ) and the running tool are engaged with a casing hanger, as shown in  FIG. 1B  (see, e.g., running tool  150 , seal assembly  172 , casing hanger  162 ). Referring again to  FIGS. 2A-2E , to operate the lock open device  200 , torque may be applied to the mandrel  204 . At a predetermined torque value, the cog  218  may slide along a ramp  219 . Although cog  218  is shown configured to engage with ramp  219 , it should be understood that multiple cogs may engage with one or more ramps without departing from the scope of the present disclosure. The predetermined torque value may depend on a slope of the ramp  219  or the force of the biasing mechanism  222 , or both. For example, a steeper slope of the incline may result in a higher resistance such that the predetermined torque value needed to overcome the resistance is higher, while a less steep slope may result in less resistance such that the predetermined torque value needed to overcome the resistance is lower. Further, a stronger biasing mechanism force may result in a higher predetermined torque value, while one or more cogs engaging with one or more ramps may also result in a higher predetermined torque value. The resistance may also depend on the profiles formed in the collar  208 , as shown and described above in  FIGS. 4A-4D . 
     As shown, the ramp  219  may extend from the slot  207  and form an angle. For a non-limiting example, the angle may be between about 45° and about 75° with respect to horizontal. In some embodiments, the angle of the ramp  219  may vary or incrementally change about the length of the ramp  219 , as will be discussed below. 
     In one or more embodiments, the form of ramp  219  may be based on the one or more cogs  218 . For example, a ramp  219  may be formed such that the shape is complementary to the one or more cogs  218 . In addition, although the ramp  219  is illustrated in  FIGS. 2A and 4A  (for example) as an incline, the ramp  219  may be any shape, such as a curve or stepped shape, among others, as discussed above with reference to  FIGS. 4C-4D . 
     As torque is applied, the cog  218  slides (or otherwise moves) along the ramp  219 , as shown in  FIG. 2B . After sliding along the ramp  219 , the cog  218  may land in an anti-return slot  223  formed within the collar  208  (see also  FIGS. 4A-4D ). The anti-return slot  223  may be configured to prevent the cog  218  from sliding back down the ramp  219 . The anti-return slot  223  may be formed to complement the shape of the cog  218 . In addition, or in the alternative, as shown in  FIG. 2C  a steep edge  221  may be formed within the collar  208  and used to prevent backward movement of the cog  218 . As the cog  218  slides up the ramp  219  and lands in the anti-return slot  223 , one or more pins  212  of the can  210  slide along slot  207  and reach an end or edge  225  of a horizontal portion of the slot  207 . In this position, the pins  212  are unable to move any further horizontally in order to prevent drill pipe wind up and/or premature unlocking of the running tool from the casing hanger. In addition, once the cog  218  lands in anti-return slot  223 , relative motion between the can  210  and the collar  208  is restricted. For example, the collar  208  and the can  210  may be configured to rotate with respect to each other, while being able to move axially independent of each other. In other embodiments, the collar  208  and the can  210  may be allowed to rotate independent of one another, while axial movement relative to each other is restricted. 
     As the pins  212  reach the end  225  of the horizontal portion of the slot  207 , the mandrel is in an actuation position and the pins  212  are able to move vertically along the slot  207  due to the shape of the slot  207 . Weight may then be set down on the drill string, as shown in  FIGS. 2D-2E , to lower the mandrel  204 . In this position, the mandrel  204  may close a valve (not shown) in a lower portion of the running tool  206 , and a seal assembly may be installed and pressure tested. Once the seal assembly is tested, the mandrel  204  and the collar  208  are free to rotate about corresponding vertical axes with respect to the lock open device  200 . Thereafter, the mandrel  204  and the collar  208  may be rotated a predetermined number of times, for example, to release the running tool  206  from the casing string. In one or more embodiments, the mandrel  204  and collar  208  may be rotated about four times to release the running tool from the casing string. A force may be applied to the mandrel  204 , raising the mandrel  204  and the collar  208 . At this point, even if the one or more pins  212  do not align with corresponding slots  207  in the collar  208 , the collar  208  will lift the can  210  and top plate  214  off of the dowel pins  224  allowing the running tool to be retrieved, as is known in the art. 
     Referring now to  FIGS. 3A-3F , cross section cut away views of resetting a lock open device in accordance with one or more embodiments are shown. In order to run the next casing string, the lock open device may need to be reset from a retrieved position, as shown in  FIG. 3A , to an initial position. Similar to the above, in  FIGS. 3A-3F , a lock open device  300  may include without limitation a number of components, such as for example a body  302  surrounding a mandrel  304  of a running tool  306 , a collar  308 , and a can  310  having one or more pins  312  configured to engage with the collar  308 . 
     With the pins  312  sitting on top of collar  308 , mandrel  304  may be rotated a predetermined number of turns, for example, to lock the running tool into a casing hanger (not shown). In embodiments, the mandrel  304  may be rotated counter-clockwise to lock the running tool into the casing hanger. However, those having ordinary skill would appreciate that one the mandrel  304  may be rotated in any direction without departing from the scope of this disclosure. 
     Once locked, the mandrel  304  may be rotated again in an opposite direction (e.g., clockwise) and in order to align the pins  312  disposed on the can  310  with the slots of the collar  308 , can  310  may be lifted and rotated. Thereafter, the pins  312  of the can  310  may be set into the slots  307  of the collar  308 , as shown in  FIG. 3B . 
     Next, screws  316  of a top plate  314  may be engaged in order to displace the top plate  314  from the can  310 , as shown in  FIG. 3C . This allows for one or more cogs  318  of the top plate  314  to extend above the anti-return slot (as shown in  FIGS. 2B-2C ). Once the one or more cogs are extended above the anti-return slot, the mandrel  304  may be rotated until dowel pins  324  align with holes in a flowtube  326 , as shown in  FIG. 3D . 
     Continuing rotation of the mandrel  304  allows the pins  312  to slide along slot  307  and position the one or more cogs  318  out from the anti-return slot (as shown in  FIGS. 2B-2C ) and above a vertical portion of the slot  307 , as shown in  FIG. 3E . This enables proper arrangement and alignment of the can  310 , collar  308 , pins  312 , and cogs  318 , and the screws  316  may be disengaged. This sets the top plate  314  onto can  310  and positions the one or more cogs  318  with respect to the collar  308 , as shown in  FIG. 3F . In this arrangement and position, the lock open device  300  is ready to run the next casing string. 
     A lock open device in accordance with embodiments of the present disclosure provides a resettable and consistent method of locking a running tool in the open position when running a casing string and seal assembly into a wellhead system. In addition, as shear pins are not being used, components of the lock open device, running tool, or other equipment do not need to be replaced between runs. As a result, time for completing the well may be saved, costs may be reduced, and the overall well completion process may be more efficiently performed. 
     Further, in accordance with embodiments of the present disclosure, a lock open device may be easier to operate as the configuration and arrangement of the components of the lock open device account for drill wind up and other potential issues when running a casing string in deep water. In addition, one or more embodiments of the lock open device may prevent prematurely unlocking the running tool from the casing before setting the seal assembly. 
     This discussion is directed to various embodiments of the invention. The drawing figures are not necessarily to scale. Certain features of the embodiments may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. It is to be fully recognized that the different teachings of the embodiments discussed may be employed separately or in any suitable combination to produce desired results. In addition, one skilled in the art will understand that the description has broad application, and the discussion of any embodiment is not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment. 
     Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present disclosure. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment. 
     Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims.