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BACKGROUND OF THE INVENTION 
       [0001]    1. Field of Invention 
         [0002]    The present invention relates to hydrocarbon well control in general and in particular method and apparatus for sealing an open well bore. 
         [0003]    2. Description of Related Art 
         [0004]    In hydrocarbon production, it is frequently desired to seal or isolate one zone of an oil well from an adjacent zone. In such situations, a sealing element is frequently used to seal and isolate the production string to the main bore or to seal adjacent zones from each other. Such sealing elements may be components of a production packer, an open hole production packer, seal adapter, pressure chamber seal adapter (with charged high pressure chamber on board), a liner hanger packer, a full bore liner top packer, a straddle type stimulation tool, a hybrid type stimulation tools (hydraulic and mechanical packer), a element made from swellable rubber compounds, an open hole seal or a cased hole seal all of which may be mechanically, hydraulically, hydrostatically or pressure chamber operated. Existing sealing elements may be of an open well or a sleeved well type. Such sealing elements may also be utilized to seal the well bore during completion, hydraulic fracturing or reworking procedures. With open well sealing elements, the sealing element is required to engage upon and form a seal with the bare rock or soil wall or formation of the well bore. Difficulties with such open well sealing elements are known to exist. 
         [0005]    Conventional sealing elements may include either a swellable or an inflatable sealing element to seal against the bore wall. Such conventional sealing elements have had difficulties achieving a proper sealed between the open bore and a sealing element. Such difficulties have resulted from several factors. One such factor is direction of the expansion of the sealing element. In particular with swellable or inflatable sealing elements, the center of the sealing element tends to racially expand to a greater amount than the edge portions thereof. This difference in swell or expansion of the sealing element provides an angular or tapered exterior surface of the sealing element that may permit a portion of the working fluid within the well bore to engage upon and exert a radially inward pressure upon the sealing element. This radially inward pressure upon the sealing element may be sufficient, at high well pressures to displace the sealing element inwards so as to create or expand a gap between the sealing element and the well bore wall, thereby compromising the seal provided by the sealing element. It will be appreciated that higher pressures, such as experienced during hydraulic fracturing, or facing procedures further exacerbates this problem. 
         [0006]    Additional factors which have made conventional sealing elements less useful, is the difficulties with inserting the sealing element into the desired location prior to expanding or otherwise activating the sealing element. Many conventional sealing elements includes a longitudinally movable actuator or driver acting upon the sealing element to radially expand it. During insertion, the longitudinally moving actuator may be prone to hanging up or otherwise being frictionally engaged upon the wall of the well bore. Such friction or hang-up may require the sealing element to have a larger insertion force applied thereto. However, such greater insertion force may also inadvertently actuate or expand the sealing element due to longitudinal movement of the actuator which is gripped by the well bore relative to the remainder of the sealing element. Additionally, it will be appreciated that a sufficiently high enough actuation force must be applied to the sealing element to prevent the hydraulic pressure in the well bore from forcing its way therepast. Previous solutions to inadvertent actuation of the sealing element has been to provide a shear pin between the longitudinal movable actuator and the remainder of the device. Such shear pins must have a preselected shear force. Difficulties have existed in selecting such a shear force to be high enough as to prevent inadvertent actuation as well as to be low enough to still permit actuation of the sealing element. 
       SUMMARY OF THE INVENTION 
       [0007]    According to a first embodiment of the present invention there is disclosed an apparatus for sealing against a bore in a soil formation. The apparatus comprises an elongate central member having a resilient tubular seal member extending between first and second ends therearound. The apparatus further including a longitudinally moveable plunger surrounding the central member and having a first wedge engagable upon the first end of the seal member and a backing ring engaging upon the second end of the seal member. The plunger being axially movable along the central member to compress the seal member between plunger and the packing ring and to press the first end of the seal member in a radially outward direction. 
         [0008]    The plunger may be movable along the elongate member by an actuator. The actuator may comprise a piston. The piston may be co-formed with the plunger. The piston may annularly surround the central member. The piston may be actuated by a fluid supplied from an interior of the central member. The seal member may include an inelastic ring disposed at the first end thereof corresponding to the plunger. 
         [0009]    The inelastic ring may be formed of metal. The inelastic ring may be formed of a plurality of segmented fingers. The plurality of segmented fingers may include at least one expandable spanning member spanning therebetween. The at least one expandable spanning member may comprise a radially expandable retaining ring. The at least one expandable spanning member may comprises at least one flange extending from each finger, adapted to overly an adjacent finger. 
         [0010]    The inelastic ring may include an angled leading surface corresponding to the first wedge of the plunger. The inelastic ring may radially inwardly bear against the central member. The inelastic ring may be selectably disengagable from the central member by the plunger wedging therebetween. The inelastic ring may be frangibley connected to the plunger. The inelastic ring may be frangibley connected to the plunger by shear pins. 
         [0011]    The apparatus may further comprise first and second seal members being disposed in opposed directions from each other having the backing ring disposed therebetween. The apparatus may further include a check valve extending through the backing ring to relieve pressure between the first and second seal members and between the backing ring and the bore. 
         [0012]    According to a further embodiment of the present invention there is disclosed a method of sealing a pipe against a bore in a soil formation. The method comprises a locating a resilient tubular seal member extending between first and second ends around the pipe at a desired location in the soil formation. Axially moving a plunger surrounding the central member towards a corresponding backing ring with a seal member therebetween so as to compress the seal member between plunger and the packing ring and to press the first end of the seal member in a radially outward direction. 
         [0013]    Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    In drawings which illustrate embodiments of the invention wherein similar characters of reference denote corresponding parts in each view, 
           [0015]      FIG. 1  is a cross-sectional view of a wellbore having a plurality of sealing elements according to a first embodiment of the present invention located therealong. 
           [0016]      FIG. 2  is a perspective view of one of the sealing elements of  FIG. 1 . 
           [0017]      FIG. 3  is a longitudinal cross-sectional view of the sealing element of  FIG. 2  as taken along the line  3 - 3  in a first or retracted position. 
           [0018]      FIG. 4  is a longitudinal cross-sectional view of the sealing element of  FIG. 2  as taken along the line  3 - 3  in a second or expanded position. 
           [0019]      FIG. 5  is a detailed cross-sectional view of the indexing rings of the sealing element of  FIG. 2 . 
           [0020]      FIG. 6  is a detailed cross-sectional view of an anti expansion device of the control valve of  FIG. 2  in a first or retracted position. 
           [0021]      FIG. 7  is a detailed cross-sectional view of an anti expansion device of the control valve of  FIG. 2  in a second or extended position. 
           [0022]      FIG. 8  is an exploded view of the sealing element of  FIG. 2 . 
           [0023]      FIG. 9  is a detailed cross-sectional view of an anti-expansion device of the control valve of  FIG. 2  in a first or retracted position according to an alternative embodiment of the present invention. 
           [0024]      FIG. 10  is and end view of the extrusion barrier of the apparatus of  FIG. 1  according to an alternative embodiment of the present invention. 
           [0025]      FIG. 11  is and end view of the extrusion barrier of the apparatus of  FIG. 1  according to an alternative embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    Referring to  FIG. 1 , a wellbore  10  is drilled into the ground  8  to a production zone  6  by known methods. The production zone  6  may contain a horizontally extending hydrocarbon bearing rock formation or may span a plurality of hydrocarbon bearing rock formations such that the wellbore  10  has a path designed to cross or intersect each formation. As illustrated in  FIG. 1 , the wellbore includes a vertical section  12  having a valve assembly or Christmas tree  14  at a top end thereof and a bottom or production section  16  which may be horizontal or angularly oriented relative to the horizontal located within the production zone  6 . After the wellbore  10  is drilled the liner  20  is of the hydrocarbon well is formed of a plurality of alternating liner or casing  22  sections separated from each other by sealing elements  24  according to a first embodiment of the present invention. As illustrated, the well bore may include one or more horizontal bores  18  from the vertical section wherein the liner  22  is located may be located within a desired horizontal bore  18 . The sealing elements are adapted to engage the well bore and seal adjacent sections of liner  22  from each other so as to permit production or completion activities to be performed on individual sections of the well bore. Optionally a sealing element  24  may be located within the vertical section  12  to isolate the desired horizontal section from the remainder of the well bore or to provide a liner hanger to suspend the liner  22  and sealing elements  24  within the desired horizontal bore  18 . In operation, between 5 and 80 sealing elements may be utilized within a wellbore to isolate zones between each although it will be appreciated that other quantities may be useful as well. 
         [0027]    Turning to  FIGS. 2 through 4 , a sealing element  24  according to a first embodiment of the present invention is illustrated. The sealing element  24  is substantially cylindrical shaped extending between first and second ends,  26  and  28 , respectively. The first end  26  includes interior threading  30  (not shown in  FIG. 2 ) and the second end  28  includes exterior threading  32  for engagement with and in-line run in with adjacent liner. The sealing element  24  comprises an elongate central tubular member  34  having a central passage  36  therethrough and at least one annular seal member  40  and  42  therearound. The seal members  40  and  42  each corresponding first and second central backing ring  90  and  91  which are located therebetween are each compressible between the backing ring and a longitudinally displaceable wedge  60  and  70  operable to compress and radially expand the annular seal into contact with the surrounding well bore. It will also be appreciated that the backing rings  90  and  91  may be formed of as a single unit. 
         [0028]    As illustrated, the sealing element  24  may include first and second seal members  40  and  42 , respectively with first and second backing rings,  90  and  91 , respectively therebetween. In such an embodiment, the first seal member  40  may be a top seal being disposed towards a top end of the well while the second seal member  42  may be a bottom seal being disposed towards a bottom end of the well. The first seal member  40  comprises a substantially tubular shaped body extending between first and second ends,  44  and  46 , respectively. The second end  46  of the first seal member abuts against and engages with the backing ring  90 . The first seal member  40  may also be bonded to the first backing ring  90  according to known methods. The first end  44  of the first seal member includes a leading extrusion barrier  48  barrier bonded thereto. The leading extrusion barrier  48  comprises a ring of rigid material extending around the circumference of the first end  44 . The extrusion barrier  48  may be segmented or formed of a plurality of independent solid members so as to form an end surface for the first seal member  40 . The extrusion barrier  48  may also be formed of a continuous ring  53  with partially independent fingers  51  extending therefrom as illustrated in  FIG. 8 . In other embodiments, the fingers  51  may be completely independent of each other. 
         [0029]    The second seal member  42  comprises a substantially tubular shaped body extending between first and second ends,  50  and  52 , respectively. The first end  50  of the first seal member abuts against and engages with the second backing ring  90 . The second seal member  42  may also be bonded to the second backing ring  91  according to known methods. The second end  52  of the second seal member includes a trailing extrusion barrier  54  bonded thereto. The trailing extrusion barrier  54  comprises a ring of rigid material extending around the circumference of the second end  52 . The trailing extrusion barrier  54  may be segmented or formed of a plurality of independent solid members so as to form an expandable end surface for the second seal member  42 . 
         [0030]    The first seal member  40  has an associated first wedge  60  associated therewith for compressing and expanding the first seal member  40 . The first wedge  60  includes an inclined surface  62  for engagement upon the leading extrusion barrier  48  of the first seal member  40  and an annular piston  64  extending in an opposed direction therefrom. The annular piston  64  extends around the tubular member  34  within an annular void  66  formed between the tubular member and a leading outer sheath  80 . 
         [0031]    The second seal member  42  has an associated second wedge  70  associated therewith for compressing and expanding the second seal member  42 . The second wedge  70  includes an inclined surface  72  for engagement upon the trailing extrusion barrier  54  of the second seal member  42  and an annular piston  74  extending in an opposed direction therefrom. The annular piston  74  extends around the tubular member  34  within an annular void  76  formed between the tubular member and a trailing outer sheath  82 . 
         [0032]    The first and second seal members  40  and  42  may be formed of any suitable pliable material as are known for use in a down hole environment, such as, by way of non-limiting example, swellable elastomers. The first and second seal members  40  and  42  may have a length selected to provide sufficient radial expansion as described below for the desired application. By way of non-limiting example, the first and second seal members may be selected to have lengths between 6 and 12 inches (152 and 305 mm) although it will be appreciated that other lengths may be useful as well. In particular, it will be appreciated that longer lengths may be utilized for open hole bores whereas shorter lengths may be utilized for sleeved or cased holes. As illustrated, the first and second seal members may have one or more internal or external grooves  39  and  41  therearound so as to facilitate the deformation of the seal members as described below. 
         [0033]    The annular voids  66  and  76  are in fluidic communication with the central passage  36  of the tubular member  34  through radial transfer bores  68  extending through the tubular member  34 . During operation, a pressurized fluid may be pumped into the central passage  36  and through the radial transfer bores  68  to displace the annular pistons  64  and  74  within the annular voids  66  so as to press the wedges  60  and  70  into the first and second seal member  40  and  40 . The wedges  60  and  70  then engage upon the leading and trailing extrusion barriers  48  and  54  of the first and second seal members  40  and  42  so as to axially compress and radially expand the seal members into engagement with the well bore as illustrated in  FIG. 4 . 
         [0034]    Turning to  FIG. 5 , a detailed view of the first end of the first seal member  40  and the first wedge  60  is illustrated although it will be appreciated that the interaction between the second seal member  42  and the second wedge  70  may be similar. The inclined surface  62  of the first wedge  60  is oriented at an incline angle, generally indicated at  65 . The leading extrusion barrier  48  includes an angled surface  47  corresponding to the incline surface  62  of the first wedge  60 . The incline angle may be selected to be between 5 and 45 degrees. It will be appreciated that lower incline angles may assist in providing a greater amount of extension force on the first seal member with a reduced distance of extension for a similar length of travel of the wedge  60 . 
         [0035]    The leading extrusion barrier  48  also includes a plurality of teeth  49  or grooves and ridges located on an inward surface  43  of the leading extrusion barrier. The teeth  49  are engaged in a corresponding set of teeth  38  on an exterior surface of the tubular member  34 . In a retracted or run-in position as illustrated in  FIG. 5 , the teeth  49  on the leading extrusion barrier  48  are engaged within the teeth  38  on the tubular member  34  so as to prevent the any longitudinal movement of the leading extrusion barrier  48  relative and therefore the first seal member  40  to the tubular member during run in of the sealing element. It will be appreciated that preventing any such longitudinal movement will prevent any unwanted activation or expansion of the seal member should the sealing element encounter an obstacle or excessive friction during run-in. During operation, when the sealing element is desired to be expanded, pressing the wedge  60  into the leading barrier lifts the teeth  49  of the leading extrusion barrier  48  out of engagement with the teeth  38  of the tubular member  34  so as to enable the seal member to be compressed and expanded as desired by an operator. As illustrated in  FIG. 6 , at an extended position, it will be observed that after the wedge  60  has extended the first end  44  of the first seal member  40 , the leading extrusion barrier  48  will be exposed to the annulus around the sealing element when the first end  44  is in contact with well bore wall. In such an orientation, the angled surface  47  of the leading extrusion barrier  48  is exposed and presents and angled surface to be engaged by a pressurized fluid surrounding the sealing element  24 . Accordingly such a pressurized fluid will exert a longitudinal as well as a radially outward force upon the leading extrusion barrier  48  as well as the first seal member  40  and thereby any pressure exerted upon the sealing element will enhance the seal provided thereby. As illustrated in  FIG. 6 , each finger  51  of the extrusion barrier  48  may be rotated by the wedge  60  such that the fingers are angularly oriented relative to the central tubular member  34 . It will be appreciated that this orientation may be achieved where the fingers  51  are connected to each other by a common ring  53 . According to an alternative embodiment, the fingers  51  may each be extended relative to the central tubular member  34  so as to be spaced apart therefrom by the wedge as illustrated in  FIG. 9  where the fingers are independent of each other. 
         [0036]    The central retaining rings  90  and  91  comprise bodies surrounding the tubular member  34  between the first and second seal members. Each of the first and second retaining rings  90  and  91  comprises a solid portion  92  and either a first and second deformable portion,  94  and  96  respectively disposed towards its respective first or second seal member  40  or  42 . The first and second deformable portions  94  and  96  comprise a plurality of longitudinally oriented fingers  98 . With reference to one of the fingers of the first deformable portion  94 , as illustrated in  FIGS. 3 ,  4  and  6 , the fingers  98  may have a substantially triangular cross section having a hinged connection at a second end  100  to the solid portion  92  and a leading edge  102  which is connected to the first seal member  40 . The leading edge  102  of the fingers may be connected to the first seal member  40  by adhesives or welding or may be held in a frictional contact therewith. During operation, when the first seal member  40  is pressed towards the retaining ring, the first seal member will bear against the leading edge  102  and rotate the fingers  98  in a radially outward direction as illustrated in  FIG. 6  until the second end  46  of the first seal member  40  engages upon the bore wall of the well. In such a position, the first seal member will be sufficiently radially expanded to such a diameter that the first end  44  of the first seal member  40  will also be engaged upon the well bore. It will be appreciated that the length of the fingers  98  will be one factor determining the maximum expansion of the seal member  40 . The fingers may have a length any desired length, however it has been found that a length of between 1.5 and 3 inches (38 and 76 mm) has been particularly useful. 
         [0037]    As illustrated in the attached figures, a shear ring  110  may be located on each of the first and second wedges  60  and  70 . With reference to the first wedge, as illustrated in  FIG. 5 , the shear ring  110  may be co-formed with the first and second sheaths  80  and  82  or may optionally be secured thereto by fasteners, welding, threading or the like. The shear ring  110  includes a plurality of shear pins  112 , which pass through the shear ring  110  and are engaged within the first wedge  60  as are commonly known. The shear pins  112  have a shear force selected by an operator so as to prevent extension of the first wedge  60  until a desired pressure is developed within the central passage  36 . In operation, this shear force may be selected to be between 1000 and 3000 psi, although it will be appreciated that other values may be utilized as well. Optionally, the wedge  60  and fingers  51  may include similar shear pins for maintaining the fingers and the sealing members in a retracted position until desired to be opened by an operator. 
         [0038]    Turning now to  FIG. 7 , a detailed view of the end of the annular piston  64  and the transfer bores  68  is illustrated showing an optional ratchet ring  120  between the annular piston  64  and the tubular member. The ratchet ring  120  comprises a cylindrical member having a slot or longitudinal gap therein and having threading or grooves and notches on both the exterior and interior surfaces thereof,  122  and  124  respectively. The inner surface of the annular piston  64  includes corresponding threading or grooves and notches,  126  and  128 , respectively. As illustrated in  FIG. 7 , the threading on the ratchet ring  120  may have a substantially triangular cross-section so as to have a substantially perpendicular face oriented towards the retracted position of the annular piston  64 . In such an arrangement, the threading  122  and  124  of the ratcheting ring  120  will assist in retaining the annular piston  64  in an extended position as illustrated in  FIGS. 4 and 6 . As illustrated in  FIG. 7 , the annular piston  64  may also includes seals  130  and  132  located therearound so as to seal the connection between the annular piston  64  and the tubular member  34  and sheath  80 . 
         [0039]    With reference to  FIG. 8 , the sealing element  24  may be assembled by locating a common backing ring  90  which may be a single or split ring design, over the tubular member  34  at a central portion thereof. The common backing ring  90  may be secured to the tubular member  34  by any known means, such as, by way of non-limiting example, welding, adhesives, threading or the like. Thereafter, the first and second seal members  40  and  42  may be located over the tubular member and abutted against the backing ring  90  and the first and second wedges  60  and  70  located over the tubular member  34  against their respective first and second seal members. The ratchet rings  120  may thereafter be inserted between the annular pistons  64  and  74  of the first and second wedges and the tubular member  34  and the annular pistons covered by the first and second sheaths  80  and  82 . It will be appreciated that in some embodiments, only one of the first or second seal member may be utilized with the other seal member, wedge and ratchet ring being omitted. 
         [0040]    Optionally, where the backing rings  90  and  91  are bonded to the seal members  40  and  42 , the sealing element  24  may be formed by slidably locating the first and second seal members  40  and  42  with their bonded backing rings  90  and  91  and leading and trailing extrusion barriers  48  and  54  and over the tubular member  34  until the first and second backing rings  90  and  91  are abutted against each other. Optionally, the first and second backing rings may be threaded onto the tubular member  34 . Thereafter the pistons  64  and  74  may be slidably located to either end of the seal members  40  and  42  with the first and second wedges  60  and  70  in contact with the leading and trailing extrusion barriers  48  and  54 . The ratchet rings  120  may thereafter be inserted between the annular pistons  64  and  74  of the first and second wedges and the tubular member  34  and the annular pistons covered by the first and second sheaths  80  and  82 . Thereafter the apparatus may be utilized as set out above within a liner string. 
         [0041]    With reference to  FIG. 10 , optionally, the extrusion barrier  48  may include a continuous expandable ring  55  applied thereto so as to provide a continuous expandable inner surface as illustrated in  FIG. 8 . The continuous expandable ring may comprise a radially expandable retaining ring  160 , having an overlap portion  162 , such as a retaining ring manufactured by Spirolox®. Optionally, each finger  51  may include a plate  170  extending therefrom so as to extend over an adjacent finger so as to provide a continuous inner surface as illustrated in  FIG. 11 . 
         [0042]    While specific embodiments of the invention have been described and illustrated, such embodiments should be considered illustrative of the invention only and not as limiting the invention as construed in accordance with the accompanying claims.

Summary:
An apparatus and method for sealing against a bore in a soil formation. The apparatus comprises an elongate central member having a resilient tubular seal member extending between first and second ends therearound, a longitudinally moveable plunger surrounding the central member having a first wedge engagable upon the first end of the seal member and a backing ring engaging upon the second end of the seal member. The plunger is axially movable along the central member to compress the seal member between plunger and the packing ring and to press the first end of the seal member in a radially outward direction. The method comprises a locating the apparatus at a desired location and axially moving the plunger towards a corresponding backing ring so as to compress the seal member between plunger and the packing ring and to press the seal member in a radially outward direction.