Abstract:
A differential pressure-operated blanking completion tool for use at a Y-Block with an electrical submergible pump (ESP) in oil or other wells. The tool has a body having an inlet and first and second outlets, the outlets being arranged in parallel and opposite the inlet; a support member located between the outlets; a sealing element mounted on the support member and rotatable with respect to the support member, the element including a substantially spherical surface; and wherein the support member is pivoted between the outlets to bring a fresh sealing surface into contact with either outlet and thereby selectively seal the respective outlet and prevent fluid flow therethrough.

Description:
BACKGROUND 
       [0001]    The present invention relates to completion tools used with electrical submergible pumps (ESP) in oil and other wells where artificial lift is utilised to improve production. In particular, though not exclusively, the invention relates to an improved differential pressure-operated blanking completion tool for use at a Y-Block. 
         [0002]    It is known in the field of oil and gas production to use artificial lift techniques to increase the flow rate of wells having a reduced bottomhole pressure. One method of artificial lift is to incorporate an ESP in the production tubing to pump the fluids to the surface of the well. The ESP can either be directly in the production tubing or located in parallel with bypass tubing. In this second arrangement a Y-Block is located in the production tubing wherein the ESP is supported from a first limb and the bypass tubing is supported from the second limb. The parallel arrangement is used when equipment needs to be run to a location below the ESP in the well. 
         [0003]    When the ESP is operated, a blanking plug must be installed in the bypass tubing to prevent pumped fluids from being re-circulated through the by-pass tubing back into the well. A disadvantage of use of a blanking plug is that in normal operations, a shut down of the pump would allow the fluid column in the production tubing above the Y-Block to drain back through the pump, possibly causing reverse rotation of the pump and allowing sand to settle in the pump—neither of which is desirable. 
         [0004]    A further disadvantage is that the blanking plug must be run-in on wireline or coiled tubing when required and pulled when the pump is switched on. These are time consuming and thus expensive interventions. 
         [0005]    An automatic blanking completion tool has been proposed in GB 2 327 961 which prevents the fluid column draining through the ESP. This tool is in the form of a modified Y-Block which automatically seals the ESP, when the ESP is switched off, and seals the bypass when the ESP is running This tool operates on the differential pressure between the bypass tubing and the ESP. A hinged flapper is mounted in the Y-Block at the point where the two limbs meet. The flapper is biased towards an open position where a first face of the flapper covers and seals the access to the ESP. When the ESP is switched on, the increase in pressure, forces the flapper over so that the opposing face covers and seals the access to the bypass tubing. Additionally when the ESP is switched off, the bias will return the flapper so that the first face again seals the access to the ESP. As fluid pressure operates the tool, no intervention is required and the tool is automatic. 
         [0006]    A disadvantage of this differential pressure-operated blanking completion tool is that the flapper deteriorates with use and as soon as one of the faces is eroded or becomes misshapen, the sealing capabilities are lost. Without a seal, a pressure-differential cannot be effectively created between the opposing faces and the flapper will not move. The entire completion tool must then be removed from the well, which prevents production causing significant delays and substantial costs. 
         [0007]    It is an object of the present invention to provide an automatic blanking completion tool which overcomes or at least mitigates disadvantages of the prior art. 
       SUMMARY OF THE INVENTION 
       [0008]    According to a first aspect of the present invention there is provided an automatic blanking completion tool comprising: a body having an inlet and first and second outlets, the outlets being arranged in parallel and opposite the inlet; a support member located between the outlets; a sealing element mounted on the support member and rotatable with respect to the support member, the element including a substantially spherical surface; and wherein the support member is pivoted between the outlets to bring the sealing element into contact with either outlet and thereby selectively seal the respective outlet and prevent fluid flow therethrough. 
         [0009]    As the sealing element can freely rotate, a fresh sealing surface is provided every time the element comes into contact with an outlet. In this way, the disadvantages of wear on the faces of the prior art flapper valve are overcome. 
         [0010]    In an embodiment, the sealing element is a wheel arranged to rotate on its axle. More particularly, the wheel is formed from a sphere from which portions are removed to provide two opposing faces of circular cross-section, with the axle being centrally located on and arranged perpendicular to the surfaces. In this way, the rim of the wheel presents a substantially spherical surface, which rotates around the axle. 
         [0011]    In an embodiment, the support member comprises a quadrilateral frame having a first side arranged between the outlets which can pivot about a first axis. More particularly, the axle of the sealing element is at a second side of the frame, opposite the first side. The second side of the frame may comprise two opposing rounded pins locating in recesses centrally located on either side of the wheel. Alternatively, the opposing rounded pins may be ends of a spindle being the axle of the wheel, which rotate in retainers on the third and fourth sides of the frame, respectively. In this way, a yoke is provided in which the sealing element is both supported and free to rotate. 
         [0012]    In another embodiment, the support member may comprise a first member arranged between the outlets which can pivot about a first axis, a second member perpendicular to the first and including a head being encompassed and retained within the sealing element. In this embodiment the sealing element may rotate relative to the second member. 
         [0013]    In an embodiment, each outlet includes a valve seat into which a portion of the spherical surface can mate. More particularly the valve seat is of circular cross-section and conical, to provide a circumferential seal with the sealing element. 
         [0014]    In an embodiment, the sealing element is retained on the support member with a loose tolerance. In this way, the sealing member exhibits ‘play’ as it rotates relative to the support member. In another embodiment, the sealing element is self-centring when it engages the outlet. In this way, the sealing performance of the tool is improved. 
         [0015]    In an embodiment, the support member is spring biased to a first position. Particularly the spring bias is provided by a plurality of torsion springs. More particularly, the support member can pivot to rotate through 180 degrees. This is required when the outlets are side by side at the same vertical position in the tool. In another embodiment, the outlets may be arranged at an acute angle with respect to each other. In this way, the support member pivots through a rotation of less than 180 degrees. Such an arrangement requires a lower differential pressure across the sealing element to operate the tool. 
         [0016]    In an embodiment, the inlet is connected to production tubing, the first outlet is connected an ESP and the second outlet connected to bypass tubing. In this way the present invention prevents the re-circulation of fluids in the well. More particularly, the inlet and second outlet are co-linear to provide a through bore to bypass tubing. This allows logging operations to be performed below the ESP. 
         [0017]    In an alternative embodiment pumps may be arranged on tubing at both the first and second outlets. This provides controlled operation of the blanking tool by being able to adjust the pressure-differential across the sealing element. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying figures where: 
           [0019]      FIG. 1  is a schematic illustration of a completion system including an automatic blanking completion tool according to an embodiment of the present invention; 
           [0020]      FIG. 2  is a cross-sectional view of an automatic blanking completion tool according to a first embodiment of the present invention; 
           [0021]      FIG. 3  is the automatic blanking completion tool of  FIG. 4  shown in an alternative cross-section; 
           [0022]      FIG. 4  a cross-sectional view through an automatic blanking completion tool with the support member moving between the outlets; 
           [0023]      FIG. 5  is the automatic blanking completion tool of  FIG. 2  with the sealing element over an outlet; 
           [0024]      FIG. 6  is a schematic illustration of the sealing element positions of the automatic blanking completion tool of  FIGS. 4 ; and 
           [0025]      FIG. 7  is a cross-sectional view of a support member and sealing element of an automatic blanking completion tool according to a second embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    Reference is initially made to  FIG. 1  of the drawings which illustrates an automatic blanking completion tool, generally indicated by reference numeral  10 , located within an ESP completion system  12 , for operating in a well bore according to an embodiment of the present invention. 
         [0027]    The tool  10  has an inlet  14  which is connected to production tubing  16 , the tubing  16  supporting the tool  10 . Opposite the inlet  14  on the tool body  18  is a first outlet  20 , connected to bypass tubing  22 . This provides a continuous vertical through bore so that wireline, coiled tubing or other strings can be run through the tool  10  into the tubing  22 . Adjacent to the first outlet  20  is a second outlet  24  from which is hung ESP tubing  26  which terminates with an ESP  28 . This arrangement provides an ESP completion system  12 , which allows for the lifting of well fluids via the ESP  28  while providing bypass tubing for access of tools for logging and other intervention below the ESP  28 . 
         [0028]    Referring now to  FIGS. 2 and 3  there are illustrated cross-sectional views through the tool  10 , according to an embodiment of the present invention. In  FIG. 2 , the view is down upon the first  20  and second  24  outlets arranged in the cylindrical tool body  18 , while  FIG. 3  shows the longitudinal view through the tool  10  between the production tubing  16  and the bypass tubing  22 . Located between the outlets  20 , 24  across the tool body  18 , is a support, generally indicated by reference numeral  30 . The support holds a sealing element  32 . 
         [0029]    The sealing element  32  resembles a sphere which has been spliced to create two opposing faces  34 , 36  by removing portions of the sphere. Each face  34 , 36  thus appears as a circular planar surface. By considering an axis through the element between the centres of the faces  34 , 36  as an axle  38 , about which the element  32  can rotate, a wheel  40  is created having a circular rim presenting a substantially spherical surface  42 . The surface  42  is smooth and continuous to create a seal. 
         [0030]    The sealing element  32  is held in a support  44  which is arranged between the outlets  20 , 24 . The support comprises a frame  46  located upon a cylindrical spindle  48 . The spindle  48  is located between a pair of mounts  50  and held so that it can rotate within the mounts  50  and with it rotate the frame  46 . Torsion springs  52  are arranged between the mounts  50  and frame  46  to bias the frame  46  into a first position over the second outlet  24  above the ESP  28 . 
         [0031]    The frame  46  resembles a yoke, having a substantially rectangular arrangement with a base  54  which is mounted on the spindle  48 . The frame  46  has sides  56 , 58  extending from the base  54  to the axle  38  of the sealing element  32 . At the axle  38  is the ‘fourth’ side of the frame  46 . In an embodiment, cylindrical protrusions from the sides  56 , 58  locate in cylindrical recesses on each face  34 , 36 . In this way, the sealing element  32  is supported on the protrusions while being able to freely rotate about the axle  38 . In an alternative embodiment, cylindrical protrusions are provided on the axle  38  extending from the centres of each of the faces  34 , 36 . Complimentary recesses are formed in the sides  56 , 58 . In this way, the sealing element  32  is supported on the sides  56 , 58  while being able to freely rotate about the axle  38 . 
         [0032]    Each outlet  20 , 24  is defined at the end of the respective tubing  22 , 26  and the body  18 . Each outlet  20 , 24  presents a circular orifice. At the orifice, the edge is cut away to provide a part conical structure at the opening to the orifice. The sloping conical surface  60  provides an improved sealing surface upon which the spherical surface  42  of the sealing element  32  can provide a seal when they come into contact. Thus a valve seat is effectively formed at each outlet  20 , 24 . 
         [0033]    In an embodiment, a space is provided between each face  34 , 36  of the wheel  40  and the inner surfaces  62 , 64  of the sides  56 , 58 . The space provides for ‘play’ of the wheel  40  between the sides  56 , 58 . This side to side travel is supported by the protrusions. Additionally, the diameter of the protrusions is machined with low tolerance in respect to the recesses, so that the diameter of the protrusions is less than the diameter of the recesses and thus the wheel  40  can move laterally in any direction aside from rotating in the frame  46 . This movement assists in allowing the sealing element  32  to effectively ‘self-seat’ or ‘self-centre’ when the wheel  40  is brought towards the conical surface  60 . 
         [0034]    In use, the ESP completion system  12  including the automatic blanking completion tool  10  is run into a well bore. During run in, fluids will be forced up the bypass tubing  22  and the ESP tubing  26 . Subsequently, the fluid pressures at the outlets  20 , 24  will be comparable which will push the frame  46  into a vertical position due to the pressure applied to both halves of the sealing element  32 . Indeed any variation is likely to only cause the wheel  40  to rotate on the axle  38 . In this mode, all fluid is forced up the inlet  14  and through the production tubing  16 . 
         [0035]    If the well fluids have insufficient pressure to rise in the tubing, the pressure at the outlets  20 , 24  will reduce to a level where the bias on the torsion springs will rotate the frame  46  on the spindle  48  until the sealing element  32  meets the outlet  24  on the ESP tubing  26 . A seal is created by the spherical surface  42  being brought onto the conical surface  60 . In an embodiment the sealing element  32  will self-align as it meets the conical surface  60 . The seal will be formed by whichever points (which form a circle) on the surface  42  of the wheel  40  are facing the surface  60  at the time of contact. As the wheel  40  is both free to rotate and will rotate with the flow of fluid pressure, this circle of points will change each time the spherical surface  42  meets a conical surface  60 . As there are an infinite number of positions which form a circle of points on the surface  42 , the sealing element  32  is not prone to wear at particular points on the surface  42 , like the flapper, and thus is less likely to be eroded or misshapen through use. 
         [0036]    With the sealing element  32  now making sealing contact with the outlet  24  at the conical surface  60 , the ESP tubing is sealed from the tool body  18 . Consequently, fluids which will now wish to travel down into the well bore are diverted through the bypass tubing  22  and such reverse circulation is prevented from occurring through the ESP  28  which prevents damage to the ESP  28 . 
         [0037]    With the ESP  28  in position, production can be taken from the well bore by the operation of the ESP  28 . The ESP artificially lifts the well fluids by pumping them up the ESP tubing  26 . On reaching the sealing element  32 , fluid pressure will break the seal between the spherical surface  42  and the conical surface  60 , lifting the wheel  40  from the outlet  24 . The continuous fluid pressure will force the frame  46  to rise, being rotated on the spindle  48 , as illustrated in  FIG. 4 . The fluid flow direction is marked on with arrows. 
         [0038]    Initially, as the fluid pressure is only sufficient to lift the fluids to the tool  10 , the fluid will recirculate to the well through outlet  20  and the bypass tubing  22 . With sufficient pressure, and the bias on the torsion springs  52 , the support  44  is rotated so that the frame  46  is brought over the first outlet  20 . It will be apparent that the wheel will likely be rotating throughout this manoeuvre, so that a fresh circle of points on the spherical surface  42  is presented onto the conical surface  60  of the first outlet  20  to form a seal. With the first outlet sealed so that fluids are prevented from being re-circulated into the well, all production is pumped through the inlet  14  and up the production tubing  16  to surface. This movement of fluid maintains the seal at the outlet  20 . This arrangement is illustrated in  FIG. 5 . 
         [0039]    When access is required to the bypass tubing  22  for intervention purposes such a logging operations below the ESP, the sealing element  32  can be automatically removed from the outlet  20 , by turning off the ESP. On turning off the ESP, well fluids are no longer pumped up the ESP tubing  26 , with the result that pressure will drop in the tool body  18  and particularly on the sealing element  32 . With the pressure drop the torsion springs  52  will have sufficient force to rotate the frame  46  on the spindle  48  and bring the wheel  40 , through  180  degrees to lie over the outlet  24 . If the pressure change and/or bias is sufficient to seal the element  32  on the conical surface  60  of the outlet  24 , then fluid is prevented from being recirculated through the ESP and any potential damage to the ESP is prevented. Again, as the wheel will rotate under the influence of fluid movement, a fresh circle of points on the spherical surface  42  is presented onto the conical surface  60  of the second outlet  24 , thereby increasing the useful life of the sealing element  32 . 
         [0040]    If the support  44  does not fully rotate to seat on the outlet  24 , tools run through the production tubing  16  and into the tool body  18  via the inlet  14 , will naturally push the support  44  out of the way towards the ESP tubing  26 , as any the leading edge of the inserted string will make contact with the wheel  40 . On contacting the wheel  40 , the downward pressure will merely cause the wheel  40  to rotate counter-clockwise upon its axle  38  while being pushed aside. This will provide no resistance to the inserted string, wireline or coiled tubing. In this way, if the springs  52  are not providing sufficient bias, they will not cause a malfunction sufficient to prevent logging operations as may occur for the prior art flapper valve arrangement. 
         [0041]    Once intervention is complete, production can be started again by merely switching on the ESP, to resume the pumping of fluids up the ESP tubing  26 , with the support  44  returning to seal the first outlet  20  as described above. 
         [0042]    The smooth movement of the wheel  40  throughout these operational steps is illustrated in  FIG. 6 . Shown in schematic cross-section, the wheel  40  is arranged such that seal points  66 , 68  are made on the outlets  20 , 24 . The seal points are related via a chord  70 , which equals the diameter of the bypass  22  or production  16  tubing respectively. As the wheel  40  can rotate freely on the axle  38  in the centre of the face  34 , an almost infinite number of chords can be determined within the circumference or rim of the wheel  40 . This illustrates the multiple available fresh sealing points which will be made each time the wheel  40  is brought into contact with an outlet  20 , 24 . Indeed, if for any reason it was felt that a suitable seal had not been formed, it is a simple matter of switching on or off the ESP accordingly for a sufficient time to merely break the seal and lift the wheel  40  off the conical surface  60 . The movement of fluid passed the wheel  40  through the outlet  20 , 24  will cause rotation of the wheel  40  and when the 
         [0043]    ESP is returned to its operating mode a fresh set of sealing points will make the seal between the sealing element  32  and the outlet  20 , 24 . The internal edge  72  of the frame  46  (see  FIG. 5 ) can also be rounded to match the outer diameter of the wheel  40  so that any debris adhering to the spherical surface  42  will be dislodged as the wheel  40  passes the edge  72  when it rotates relative to the frame  46 . 
         [0044]    Reference is now made to  FIG. 7  of the drawings which illustrates an alternative embodiment of the support  44 . Like parts to those of the earlier Figures will be given the same reference numeral with the addition of  100  to aid clarity. Support  144  is provided with a spindle  148  and a frame  146 . The spindle  148  will be similar to the first embodiment so that it can be supported and rotate within mounts  150  (not shown). The frame  146  is connected to the spindle  148  as before, but now comprises a cylindrical shaft  74  extending from the spindle  148  and terminating at a head  76 . Surrounding the head  76  is the sealing element  132 . The sealing element  132  is a spherical member having a circular aperture  78  through which the shaft  74  extends. The shape of the head  76  is selected so that the element  132  can rotate freely around the shaft  74 . Some tolerance may be selected to give ‘play’ between the components so that the sealing element  132  can self-centre in the same fashion as the first embodiment. 
         [0045]    It will be understood that while the description has been provided for a tool  10  with bypass tubing and ESP tubing depending from each outlet, ESP tubing may depend from both outlets. In this arrangement by sequencing the operation of the ESP&#39;s the fluid pressure can be controlled at the tool body to effect the rotation of the support and consequently the respective sealing of the desired ESP tubing. Thus, recirculation is prevented through each ESP when the alternative ESP is switched on. 
         [0046]    An advantage of embodiments of the present invention is that it provides an automatic blanking completion tool which presents a fresh surface for sealing an outlet of the tool each time a seal is required. 
         [0047]    Various modifications may be made to the invention herein described without departing from the scope thereof. For example, other arrangements for supporting the sealing element may be used which still allow the sealing element to rotate with respect to the support, and the support to rotate with respect to the body. 
         [0048]    This written description uses examples to disclose the invention, including the preferred embodiments, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.