Patent Publication Number: US-9903183-B2

Title: Method and apparatus for catching and retrieving objects in a well

Description:
CROSS REFERENCES TO RELATED APPLICATION 
     This application is a continuation of U.S. Non-provisional patent application Ser. No. 13/873,718, filed Apr. 30, 2013, currently pending, which was a continuation-in-part of U.S. Non-provisional patent application Ser. No. 13/553,915, filed Jul. 20, 2012, which claims priority of U.S. Provisional Patent Application Ser. No. 61/510,229, filed Jul. 21, 2011, and U.S. Provisional Patent Application Ser. No. 61/610,757, filed Mar. 14, 2012, all incorporated herein by reference. 
    
    
     STATEMENTS AS TO THE RIGHTS TO THE INVENTION MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
     None 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention pertains to a method and apparatus for preventing unwanted objects from entering subterranean portions of a wellbore. More particularly, the present invention pertains to the use of magnetic field(s) to catch unwanted objects within a wellbore. More particularly still, the present invention pertains to an apparatus for generating magnetic field(s) between a rig floor of a drilling or completion rig and a wellhead, such as in or near a bell nipple or riser assembly, in order to prevent unwanted objects from entering a wellbore below said wellhead. 
     2. Brief Description of the Prior Art 
     A bell nipple is a large diameter length of pipe utilized on most drilling and completion rigs. In most cases, a bell nipple is installed at or near the top of a rig&#39;s blowout preventers and extends to a well&#39;s uppermost opening at the rig floor; the bell nipple typically serves as a “funnel” to guide drilling tools and/or other equipment into and out of the upper opening of a well. Most conventional bell nipples also serve as conduits for drilling muds and/or other fluids present within a well. As such, most conventional bell nipples are typically configured with a side outlet to permit fluid to flow from a well to a rig&#39;s surface fluid equipment such as shale shakers and mud tanks. 
     Unfortunately, not all objects that a bell nipple guides into a wellbore are beneficial. Objects can sometimes accidentally fall into the uppermost opening of a well from the rig floor. In other instances, objects can be purposely thrown or dropped into a well as an intentional act of sabotage. If such objects are not stopped before entering the subterranean portion of the wellbore, the objects can prevent downhole equipment from functioning properly and can often impede the drilling and/or completion process. 
     Relatively large objects can generally be retrieved from a wellbore using specially designed “fishing tools.” Such fishing tools are lowered into a wellbore and connect to a dropped object within the wellbore. Thereafter, the fishing tools and the connected object can both be safely retrieved from the wellbore. In many instances, the retrieval process for such large objects can be relatively simple because the size of the objects enables such objects to be grasped and lifted out of the wellbore. 
     By contrast, relatively small objects dropped in a wellbore—and particularly metal objects—can often cause the most disruption to downhole equipment and related operations. For example, during completion operations, small pieces of metal present in a wellbore can prevent packers and other completion tools from sealing against a casing wall. During open hole drilling operations, such small metal objects can destroy very expensive downhole equipment such as Polycrystalline Diamond Compact (PDC) bits. 
     Such small objects can also be very difficult to retrieve from a wellbore, as they are often too small to be grasped using conventional fishing tools. This is especially true for small metal objects and, in particular, small metal objects that have an irregular shape or small pieces that can be broken up during the retrieval process. Unfortunately, drilling rigs typically have many small metal objects (such as, for example, wrenches, chain, bolts, tong dies and nuts) at or near the rig floor. Such objects, which are in relatively close proximity to the upper opening of a well, are at risk of falling into a wellbore. 
     As noted above, such relatively small metal objects can cause significant disruptions to downhole operations. Further, fishing operations for small metal objects can be very time consuming and, as a result, very costly. Accordingly, the best way to prevent such disruptions and to avoid long and expensive fishing operations for such small objects is to keep such objects from entering a wellbore in the first place. 
     Rig operating procedures frequently dictate that when no pipe is present in a wellbore that blind rams in a blowout preventer (“BOP”) assembly be closed in order to block access to subterranean portion of said wellbore and keep any unwanted falling objects from entering said wellbore from above the BOP assembly. If an object is dropped into a well at the rig floor, with such BOP blind rams closed, the object will not fall all the way into the subterranean portion of a wellbore. However, this solution is less than optimal, because the object must still be retrieved from the top of the rams before operations can resume. Such retrieval process typically requires draining such BOP assembly of fluids to locate the object, opening the bonnet in the BOP assembly, finding and retrieving the object, and then closing and retesting the BOP assembly to the required test pressures. This retrieval process—while frequently quicker and less expensive than fishing the item from the bottom of the well—is nonetheless still relatively expensive, time consuming and dangerous for personnel. 
     Thus, there is a need for an apparatus and method for catching dropped objects, and particularly metallic objects, before such objects enter the subterranean portion of a well. Such apparatus and method should prevent dropped objects from falling further into a wellbore, and should hold such objects for ultimate retrieval and removal from a wellbore. As an added benefit, such apparatus should also allow for the removal of metallic debris from well fluids. Such apparatus can be disposed at virtually any location(s) between a rig floor of a drilling or completion rig, and a wellhead assembly of a well. In many cases, said apparatus can be conveniently and effectively situated at or in proximity with a bell nipple assembly, or as part of a riser assembly on a floating drilling rig. 
     SUMMARY OF THE PRESENT INVENTION 
     The present invention comprises an apparatus for generating a magnetic field that can be attached to, placed in the vicinity of, or made a part of a wellbore. The magnetic field is used to catch falling metal and/or magnetic objects from passing beyond a wellhead and entering the subterranean portions of a wellbore. Said magnetic field can also catch ferrous metallic and/or other magnetic objects and debris present in well fluids, and permit easy and efficient removal thereof. 
     A magnet assembly of the present invention comprises at least one magnet and is disposed on, around, or as an integral part of a wellbore. The magnet(s) of the magnet assembly of the present invention can be sized based on the internal diameter of a wellbore, as well as the ability to catch certain representative objects that have been dropped into or fished out of wellbores. 
     In the preferred embodiment, the magnet assembly of the present invention can be mounted at or near the bell nipple. Typically, the magnet assembly of the present invention can be installed between the upper surface of a BOP assembly and the lower portion of a bell nipple assembly. However, it is to be observed that such magnet assembly can be placed in other areas such as, for example, within a riser assembly situated between a subsea wellhead and a floating drilling vessel. 
     The magnets of the present invention are removably mounted and can be selectively moved away from a wellbore when desired. For example, it may be beneficial to selectively move said magnets away from said wellbore to prevent magnetic interference with logging tools or other equipment that may be sensitive to magnetic fields, or when circulating large concentrations of metallic debris in a rig fluid system (such as, for example, when milling up stuck metal objects in a well). Movement of said magnets can be manually performed, or remotely actuated using pneumatic or hydraulic powered assemblies. 
     In the preferred embodiment, the magnet assembly of the present invention comprises a central housing member defining an internal chamber, as well as an inlet and outlet in communication with said internal chamber. Hinged and recessed hatch doors allow selective access into said internal chamber. Hinged magnet members, which can be partially received within recesses formed in said hatch doors, are mounted in proximity to said hinged hatch doors. Further, said hinged magnet members and hatch doors can be selectively positioned relative to one another. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description of the preferred embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, the drawings show certain preferred embodiments. It is understood, however, that the invention is not limited to the specific methods and devices disclosed. Further, dimensions, materials and part names are provided for illustration purposes only and not limitation. 
         FIG. 1  depicts a side perspective view of a magnet assembly of the present invention in a closed position. 
         FIG. 2  depicts an overhead view of a magnet assembly of the present invention in a closed position. 
         FIG. 3  depicts a side perspective view of a magnet assembly of the present invention with the magnet members in an open position. 
         FIG. 4  depicts an overhead view of a magnet assembly of the present invention with the magnet members in an open position. 
         FIG. 5  depicts a side perspective view of a magnet assembly of the present invention with the hatch door members in an open position. 
         FIG. 6  depicts an overhead view of a magnet assembly of the present invention with the magnet members and hatch doors in an open position. 
         FIG. 7  depicts an overhead sectional view of the magnet assembly of the present invention. 
         FIG. 8  depicts a side sectional view of a conventional wellbore configuration having a ball nipple assembly, BOP assembly and well head assembly. 
         FIG. 9  depicts a side sectional view of a wellbore equipped with a magnet assembly of the present invention. 
         FIG. 10  depicts an alternate side sectional view of a wellbore equipped with a magnet assembly of the present invention. 
         FIG. 11  depicts an alternate side sectional view of a wellbore equipped with a magnet assembly of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION 
     Referring to the drawings,  FIG. 1  depicts a side perspective view of a magnet assembly  10  of the present invention in a closed position. Generally, said magnet assembly  10  of the present invention can be installed in relatively close proximity to the upper opening of a wellbore (such as, for example, near a bell nipple assembly). Said magnet assembly  10  generates a magnetic field that is beneficially directed inwardly toward said wellbore to in order to catch falling magnetic (such as, for example, metallic) objects and prevent such objects from entering a subterranean portion of said wellbore, as more fully described herein. 
     Still referring to  FIG. 1 , magnet assembly  10  comprises central housing member  11 . As depicted in  FIG. 1 , said central housing  11  comprises a substantially hollow, box-shaped enclosure having an internal chamber that defines an inner volume. However, it is to be observed that central housing  11  can exhibit any number of different shapes or configurations while remaining functional and without departing from the scope of the present invention as set forth herein. 
     Upper tubular extension  12  extends from the upper surface of central housing member  11 , while lower tubular extension  14  extends from the bottom surface of said central housing member  11 . Said upper tubular extension  12  and lower tubular extension  14  are axially aligned with one another, and both open into and are in communication with the inner chamber of central housing member  11 . 
     In the preferred embodiment depicted in  FIG. 1 , said upper tubular extension  12  has a central through bore defining an inner surface  13  having internal threads  13   a . Lower tubular extension  14  has a central through bore (not depicted in  FIG. 1 ), drain port  15  and lower base connection flange  16  having bolt holes  17 . The central bores of upper tubular extension  12  and lower tubular extension  14  are in substantial axial alignment and fluid communication with the internal chamber of central housing member  11 . 
     Although said magnet assembly  10  can be installed within a wellbore in many different configurations, in the preferred embodiment said magnet assembly  10  can be installed immediately above a BOP assembly with said base connection flange  16  mating with the upper connection flange of said BOP assembly (typically the uppermost connection flange of an annular blowout preventer). A bell nipple can connect to upper extension member  12 . In this manner, said magnet assembly  10  can be installed “in-line” between said BOP assembly and said bell nipple assembly. 
       FIG. 2  depicts an overhead view of magnet assembly  10  of the present invention in a closed position. Central housing  11  comprises a substantially hollow box-shaped enclosure defining an internal chamber having a volume. Upper tubular extension  12  extends from the upper surface of central housing member  11 ; said upper tubular extension  12  has a central through bore defining an inner surface  13 . 
     It is to be observed that an unobstructed bore and flow path is formed through magnet assembly  10 . Specifically, said bore and flow path extends through upper tubular extension  12 , central housing member  11  and lower tubular extension  14  (not shown in  FIG. 2 ). As such, when said magnet assembly  10  is installed “in-line” within a wellbore (such as, for example, between a BOP assembly and bell nipple assembly, or in the riser assembly of a floating drilling vessel), an unobstructed passage way and a direct flow path exists through said magnet assembly  10 . 
     Still referring to  FIG. 2 , hatch door members  50  are connected to central housing member  11  using hinge assemblies. Specifically, each hinge assembly comprises a housing hinge member  31  pivotally connected to hatch door hinge member  32  using hinge pin  33 . Said hinge assemblies permit each such hatch door members  50  to open or swing outward relative to housing member  11  about an axis passing through said hinge pin  33 . When said hatch doors  50  are open, access is permitted into the inner chamber of central housing  11 ; said hatch doors  50  essentially act as so-called “stripper doors” that allow access into the inner chamber of housing  11 . 
     Referring back to  FIG. 1 , said hatch door members  50  are both in a closed position. Each hatch member  50  has outer hatch plate  51  having substantially flat surfaces, which contacts and engages against substantially flat surfaces of hatch frame  20 . Said hatch members  50  can be selectively secured in a closed configuration, or unsecured as discussed in detail herein. In the configuration depicted in  FIG. 1 , magnet members  70  are partially received within recesses formed by hatch doors  50 . 
     Referring to  FIG. 2 , magnet members  70  are also hingedly attached to central housing member  11 . Specifically, magnet hinge member  71  of each magnet member  70  is pivotally connected to housing hinge member  31  using hinge pin  33 . Said hinge assemblies permit said magnet members  70  to swing outward relative to housing member  11  and/or hatch doors  50 , about an axis passing through said hinge pin  33 . It is also to be observed that said magnet members  70  and hatch doors  50  can independently pivot or hinge about an axis passing through said hinge pin  33 . Handles  71  are provided on magnet members  70  to facilitate gripping and moving of said magnet members  70 . It is also to be observed that magnet members can also be hingedly connected to hatch door members  50  without departing from the scope of the present invention. 
       FIG. 3  depicts a side perspective view of magnet assembly  10  of the present invention with hatch doors  50  secured and locked in a closed position, and magnet members  70  in an open or extended position. Said hatch doors  50  are closed and secured in place relative to housing  11  using locking clamp members  21 , while magnet members  70  are pivotally extended (that is, swung open) relative to said hatch doors  50  and housing  11 . When in the closed and secured position, hatch doors  50  can form a fluid pressure seal with housing  11  of magnet assembly  10 . It is to be observed that gasket members or elastomeric sealing members may be disposed between outer hatch plate  51  and hatch frame  20  to further facilitate a fluid pressure seal when hatch doors  50  are secured in a closed-position. 
     In the preferred embodiment of the present invention, said magnet members  70  comprise rare earth or ceramic magnet segments  73  exhibiting desired magnetic characteristics (that is, creating their own persistent magnetic fields). Further, in the preferred embodiment, each of said magnet members  70  has magnet segments  73  oriented in a V-shaped configuration, which helps to focus the magnetic field(s) generated by said magnet members  70 . 
     Still referring to  FIG. 3 , in the preferred embodiment, hatch door members  50  each have an outer surface that beneficially defines substantially parallel recessed areas  56  that are disposed on both sides of central convex semi-cylindrical member  57 . Said hatch door members  50  and magnet members  70  can open and close independently of each other. As such, it is to be observed that, when said magnet members  70  and hatch doors  50  are joined together, said V-shaped magnet segments  73  of magnet members  70  are partially received within recessed areas  56  defined by said hatch doors  50 . In this position, said magnet segments  73  of said magnet members  70  are partially subsumed within said hatch doors  50 . 
       FIG. 4  depicts an overhead view of a magnet assembly  10  of the present invention with magnet members  70  in an open or extended position. Hatch doors  50  are closed and secured in place relative to housing  11  using locking clamp members  21 . Magnet members  70  comprised of V-shaped magnet segments  73  are pivotally extended or swung open relative to said hatch doors  50  and housing  11 . 
     As depicted in  FIG. 4 , magnet members  70  of said magnet assembly  10  can be selectively opened away from the central axial through-bore  90  formed through magnet assembly  10  when desired. For example, it may be beneficial to selectively move said magnets members  70  away from central axial through-bore  90  formed through magnet assembly  10  to prevent magnetic interference with logging tools or other equipment that may be sensitive to magnetic fields, or when circulating large concentrations of metallic debris in a rig mud system (such as, for example, when milling up stuck metal objects in a well). It is to be observed that said assembly for repositioning said magnets can be manually operated (as depicted herein), or remotely actuated using pneumatic or hydraulic powered means well known to those having skill in the art. 
       FIG. 5  depicts a side perspective view of magnet assembly  10  of the present invention with hatch door members  50  in an open position. As depicted in  FIG. 5 , in the preferred embodiment, said hatch door members  50  can be selectively opened to provide access to the internal chamber within central housing  11 . Internal surface  52  of each hatch door  50  defines substantially parallel wedge-shaped members  53 . Said wedge-shaped members  53  are oriented substantially vertically, while a concave semi-cylindrical recess  54  is disposed between said wedge-shaped members  53 . Lateral wedge-shaped stand-off members  58  having end strip  59  are disposed within inner chamber of central housing  11 . 
       FIG. 6  depicts an overhead view of magnet assembly  10  of the present invention with magnet members  70  and hatch doors  50  in an open position. Said hatch door members  50  can be selectively opened to provide access to an internal chamber within central housing  11 . Each hatch door  50  includes substantially parallel internal wedge-shaped members  53  and concave semi-cylindrical recess  54 . 
       FIG. 7  depicts an overhead sectional view of magnet assembly  10  of the present invention. Referring to  FIG. 7 , when both of said hatch doors  50  are closed, it is to be observed that semi-cylindrical concave recesses  54  of said opposing hatch doors  50 , as well as lateral wedge-shaped stand-off members  58 , cooperate to form a substantially cylindrical through-bore  90  extending vertically through said central housing member  11 . In this manner, an unobstructed path is formed through magnet assembly  10 —that is, an obstructed bore extends through magnet assembly  10  via aligned upper tubular extension  12 , central housing member  11  and lower tubular extension  14 , as depicted in  FIG. 1 , for the passage of tools or equipment, as well as the flow of fluid. 
     Still referring to  FIG. 7 , said hatch door members  50  and magnet members  70  can open and close independently of each other. As such, it is to be observed that, when said magnet members  70  and hatch doors  50  are joined together, said V-shaped magnet members  70  are partially received within recessed areas defined by said hatch doors  50 . In this position, said magnet members  70  are partially subsumed within said hatch doors  50 , and are beneficially positioned proximate to said central through-bore  90 . 
       FIG. 8  depicts a side sectional view of a conventional wellbore configuration on a drilling rig. As depicted in  FIG. 8 , bell nipple  120  is connected at its upper end to rotary assembly  130 , and at its lower end to blowout preventer (“BOP”) assembly  110 . Rotary assembly  130  is mounted at rig floor  140  having upper surface  141 , and defining an upper opening  131 . BOP assembly  110  is connected to wellhead  100  which is mounted to the upper portion of a wellbore (not shown in  FIG. 3 ) extending into the earth&#39;s crust. BOP assembly  110  generally comprises ram assembly  111  and annular preventer assembly  112 . 
     Bell nipple assembly  120  acts as a “funnel” to guide drilling tools into and out of the upper opening of a wellbore. Unfortunately, not all objects that a bell nipple guides into a wellbore are beneficial, such as chain segment  150  that is depicted falling in central through-bore  124  of bell nipple assembly  120 . If falling objects such as chain segment  150  are not stopped before entering the subterranean portion of a wellbore, such objects can prevent downhole equipment from functioning properly and can often negatively impede the drilling process as detailed herein. 
       FIG. 9  depicts a side sectional view of a wellbore equipped with the magnet assembly  10  of the present invention. Magnet assembly  10  of the present invention, and more particularly magnet members  70  thereof, create an inwardly directed magnetic field. In the preferred embodiment, said magnetic field is generally focused or directed toward central through-bore of said magnet assembly, which is in alignment with said wellbore. As a result, metal objects dropped into the upper opening  131  of a well, such as chain segments  150 , are caught in said magnetic field  21 ; accordingly, such metal objects do not pass magnet assembly  10 , and do not enter the subterranean portions of a wellbore. Such objects (such as, for example, chain segments  150 ) can be easily retrieved from magnet assembly  10 . 
     It is to be observed that the magnet assembly  10  of the present invention can be disposed at virtually any position along the distance that exists between: (1) a rig floor of a drilling or completion rig; and (2) a wellhead of a well being serviced by said drilling or completion rig. For example, it is possible that said magnet assembly of the present invention and related method could be incorporated directly within a BOP assembly or wellhead assembly. Additionally, when installed in connection with a floating drilling vessel, it is to be observed that magnet assembly  10  of the present invention can be installed as part of the riser that extends from a rig to a subsea BOP assembly. However, without limiting the scope of the present invention in any manner, the simplest and most effective manner of implementing the present invention will frequently involve installing the magnet assembly of the present invention between a BOP assembly and a bell nipple assembly as described herein. 
     Said magnet assembly  10  can be beneficially situated above or below the side outlet of said bell nipple; however, as depicted herein, when said magnet assembly  10  is installed between a bell nipple assembly and BOP assembly, said magnet assembly  10  will be situated below said fluid outlet part. Because any liquid in central through-bore  124  of bell nipple assembly  120  drains through said side outlet port  121 , the liquid level within said through-bore  124  does not extend above said outlet port  121 . Accordingly, magnet assembly  10  can be positioned below said outlet port  121  of bell nipple assembly  120 . In such an installation, the magnetic field generated by magnet assembly  10  extends into a “wet” portion of bell nipple assembly  120  (that is, a portion of bell nipple central through-bore  124  that contains drilling mud or other liquid). 
       FIG. 10  depicts an alternate side sectional view of a wellbore equipped with magnet assembly  10  of the present invention. As depicted in  FIG. 10 , magnet members  70  of said magnet assembly  10  are shown in the extended or open position. In this position, the magnetic field generated by said magnet members  70  is not directed toward the inner chamber of central housing  11  of magnet assembly  10 . As such, metallic chain segments located within said magnet assembly  10  are not caught within said magnetic field, and would be able to pass by magnet assembly  10  when falling from upper opening  131 . 
     As noted above, in certain circumstances, it may be beneficial to selectively position said magnets members  70  temporarily away from central housing  11  of magnet assembly  10  in order to prevent magnetic interference with logging tools or other equipment that may be run into a well equipped with magnet assembly  10 . Similarly, it may also be beneficial to selectively position said magnets members  70  temporarily away from central housing  11  when circulating large concentrations of metallic debris in a rig mud system (such as, for example, when milling up stuck metal objects in a well) in order to prevent clogging of magnet assembly  10 . Notwithstanding the foregoing, in other circumstances, it may be beneficial to remove metallic particles or debris from wellbore fluids using magnet assembly  10 . 
       FIG. 11  depicts an alternate side sectional view of a wellbore equipped with magnet assembly  10  of the present invention. As depicted in  FIG. 11 , hatch doors  50  (including attached magnet members  70 ) of said magnet assembly  10  are shown in the extended or open position. In this position, said open hatch doors  50  permit access into the inner chamber of central housing member  11  (and, thus, the wellbore). Because magnet members  70  remain in close proximity to said hatch doors  50 , the magnetic field generated by said magnet members  70  is directed through said open hatch doors  50 . As such, metallic chain segments  150  located within said wellbore are caught within said magnetic field even with said hatch doors  50  open, and can be removed from the inner surface of said open hatch doors  50 . 
     In operation, magnet assembly  10  of the present invention can be used to quickly and efficiently capture certain objects dropped in a well. When such an object is dropped into a well, the BOP assembly can be closed as a “fail-safe” to prevent access into a wellhead and the upper portion of a wellbore. Thereafter, any drilling mud or other fluid can be drained from inside said magnet assembly  10  via drain port  15 . One hatch door  50 , with an applicable magnet member  70  (or, more particularly, magnet segments  73  thereof) still partially received within said hatch door, can be opened completely to provide access into the inner chamber of central housing  11 . (In most instances, both hatch doors  50  are not opened simultaneously in order to prevent possible loss of magnetic forces on a caught object, particularly if such object spans substantially across the width of magnet assembly  10 ). Once the object is removed, hatch door(s)  50  can be closed and locked in place. Thereafter, the BOP assembly can be opened, and drilling or other operations can be resumed. 
     In many cases, milling of downhole equipment or other wellbore operations can generate metallic shavings, particles or other debris supported in drilling mud or other fluid within a wellbore. Although efforts are made on virtually all rigs to remove debris and contaminants from drilling mud or other fluids, over time such metallic shavings, particles and/or debris can reach significant concentrations in such drilling mud or other fluids. Such metallic content can adversely affect fluid properties, equipment performance and/or operational effectiveness. Thus, it is generally beneficial to remove such metallic materials from such drilling muds or other fluids. 
     Although magnet assembly  10  of the present invention can be used to catch falling objects, said magnet assembly  10  can also serve the function of catching undesirable metallic materials from drilling mud or other fluid. Such metallic material materials can often attach to the internal surface of hatch doors  50 . Moreover, any such metallic material can be recovered and measured, which can frequently provide valuable insight into ongoing operations within a well. 
     The above-described invention has a number of particular features that should preferably be employed in combination, although each is useful separately without departure from the scope of the invention. While the preferred embodiment of the present invention is shown and described herein, it will be understood that the invention may be embodied otherwise than herein specifically illustrated or described, and that certain changes in form and arrangement of parts and the specific manner of practicing the invention may be made within the underlying idea or principles of the invention.