Patent Publication Number: US-11391118-B2

Title: Plug with resettable closure member

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of and claims the benefit of an earlier filing date from U.S. Continuation-in-part application Ser. No. 16/844,728 filed on Apr. 9, 2020, and U.S. Non-Provisional application Ser. No. 16/778,859 filed Jan. 31, 2020, the entire disclosures of each of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     In the resource recovery industry, it is common to set plugs in a borehole environment to allow pressure based operations to be undertaken closer to a pressure source such as a surface location. Examples of such plugs include frac plugs (or packers, and the like) that are set in a borehole to facilitate fracturing a formation uphole of the frac plug. Frac plugs are commonly configured as conical seat structures receptive to a dropped ball for plugging. These work well but require large volumes of pumped fluid to convey balls to their seats and also require that the balls be recirculated back out of the well if a run such as a replacement perf gun is required. Flappers have been tried and successfully reduce pumped fluid requirements but suffer the same drawbacks vis-à-vis the pumping of any component after the flapper has been seated. 
     SUMMARY 
     Disclosed is plug with a resettable closure member comprising a body defining a flow bore, a closure member movable between a position closing the flow bore and a position wherein the flow bore is open, the closure member responsive to a selected hydrodynamic force to move to the position closing the flow bore and responsive to an attractive magnetic force to move to the position wherein the flow bore is open. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG. 1  is a schematic cross-sectional view of a plug with a resettable closure member as disclosed herein; 
         FIG. 2  is a view of the plug illustrated in  FIG. 1  rotated 90 degrees; 
         FIG. 3  illustrates another feature of  FIG. 2 ; 
         FIG. 4  illustrates another feature of  FIG. 2 ; 
         FIG. 5  illustrates another feature of  FIG. 2 ; 
         FIG. 6  illustrates an alternative feature of  FIG. 2 ; 
         FIG. 7  illustrates another position for the alternative feature of  FIG. 2   
         FIG. 8  illustrates an alternative arrangement of the closure member for all embodiments in an open position; 
         FIG. 9  illustrates the alternative arrangement of the closure member of  FIG. 8  in a closed position; 
         FIG. 10  illustrates the alternative arrangement of the closure member of  FIG. 8  in an intermediate position between that of  FIG. 6  and  FIG. 7 ; and 
         FIG. 11  is a schematic view of a wellbore system having the plug of  FIG. 1  disposed therein. 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
     Referring to  FIG. 1 , a plug  10  is illustrated. The plug  10  comprises a cone body  12  (that can itself be one or more pieces), slip(s)  14 , and seal  15 . The plug  10  further comprises a flow bore  16 , a closure member seat  18 , and a closure member assembly  20 . 
     Closure member assembly  20  is a resettable assembly even while in a borehole in use. In other words, the closure member assembly will hold a closure member  22  in an open position and then allow that member  22  to close responsive to a selected hydrodynamic force. Once the assembly releases the member  22  in response to the selected threshold hydrodynamic force being experienced by the assembly  20 , the closure member  22  (illustrated as a flapper) will close against the seat  18 . The hydrodynamic force is created by a flow rate (but not below that rate) of a fluid flowing through the flow bore  16  and resetting upon flowback of fluid through the flow bore  16  in the opposite direction (reverse flow). Hereby, the plug  10  may remain open to flow indefinitely while being closable simply by increasing the flow rate to above the selected threshold flow rate whereat the closure member  22  will close against seat  18 . Importantly, the plug  10  may also be reopened by the reversed flow and will automatically reset the closure member  22  to its open position prior to having been subjected to the selected threshold flow rate. The closure member  22  will stay that way indefinitely until the flow rate is again raised to beyond the selected rate. The plug is hence resettable any number of times at the whim of the operator without need for pulling the plug from the borehole. This functionality is particularly useful in the case of a fracturing operation or injection treatment. It will be appreciated that occasionally during a frac operation, the perf guns (not shown) fail to discharge. In such condition the guns must be withdrawn from the borehole and new guns pumped in. In prior art systems, the pumping back in is not possible if the frac plug is closed. Without fluid flow through the frac plug, the guns may not be pumped to position. Accordingly, plugs of the prior art must be removed altogether or at least the ball on seat would need to be flowed out of the well before new guns could be pumped into place. The plug  10  allows replacement of guns without need for ancillary activities. The plug  10  will automatically reset itself upon pulling of the guns since the attendant flowback of fluid through the plug  10  will push the closure member  22  off seat  18  and flow it back toward its fully open position whereat it will be automatically secured. 
     The assembly  20  includes a frame  24  (which may be a separate member or a part of the cone body  12  itself) and a magnetic catch  26  (a hold open feature). In one embodiment the magnetic catch  26  comprises two magnets  28  and  30  that are attractively interactive with each other. As illustrated magnet  28  is mounted on the frame  24  and magnet  30  is mounted on the closure member  22  and they are aligned with one another when the closure member  22  is in the open position. It will be appreciated that movement of the closure member  22  is pivotal, dictated by pivot pin  32  and so the magnets  28  and  30  will be aligned and attracted to one another when brought near one another through pivotal movement of the closure member  22  toward the open position. In alternate embodiments, either of  28  or  30  may be substituted by a magnetically permeable material such as a ferrous member. In yet another embodiment, flowback or other input to bring the closure member  22  nearer the frame  24  is unnecessary. The need for input in this regard is eliminated by ensuring that the attractive magnetic force acting between the frame  24  and the closure member  22  persists even when the closure member  22  is in the closed position. That is to say that the closure member  22  is always being magnetically urged to the open position by a larger magnetic field (generated via permanent magnet(s) electromagnet(s), etc.) and only occupies the closed position due to external input such as by experiencing the selected hydrodynamic force or by experiencing a pressure differential across the closed closure member  22 . If neither of those inputs (or other closing input) is present, the closure member will naturally migrate to the open position due to the attractive magnetic force between the frame  24  and the closure member  22 . 
     Referring to  FIG. 2  along with  FIG. 1  now, it is to be appreciated that an actuation opening  34  exists in the cone body  12 . It will be appreciated by those of skill in the art that fluid flowing from a left of the figure will flow around and outside of the uphole end  36  of the cone body  12  and then through the opening  34  as well as through the flow bore  16  (see double arrows in  FIG. 1 ). The fluid flowing through the opening  34  hydrodynamically loads the closure member  22 . At a selected flow rate, the hydrodynamic load will exceed the holding capability of the magnetic catch  26  and cause the closure member  22  to pivot to a seated position against seat  18 . In an embodiment, the magnetic catch is set to hold 16 lbs of load and that equates to 15 barrels per minute flow rate. Therefore, any operation below 15 barrels per minute (BPM) may progress without the member  22  closing but at a rate of greater than 15 BPM, the member  22  will close. It is to be understood that the flow rate noted is for water at ambient surface temperature. If the temperature is higher, the rate will need to be higher to compensate for the lower density of the water. Alternatively, if the flow is of a downhole fluid, the density may be higher and accordingly the flow rate of such fluid may be lower yet still be sufficient to cause the magnetic catch  26  to release the closure member  22 . Precisely at what force the catch  26  releases is adjustable in a number of ways. One way to adjust (reduce) the force is to increase distance between the member  22  and frame  24 . This can be accomplished in an embodiment by inserting a nonmagnetic material between the member  22  and frame  24 . The thickness of that inserted nonmagnetic material (and hence the distance between magnets) will dictate the attenuation of the magnetic field available to hold the member  22  in the open position according to the statement 1/distance 2 . Another way to adjust the magnetic catch (reduce or enhance) is to change the size or geometry of magnets used or to change the magnetically permeable material used in the catch system to increase or decrease the field created. 
     It should be appreciated that the figures also illustrate holes  38  (one or more of them) in the cone body  12 . These holes reduce the hydrodynamic force upon the closure member  22  relative to a cone body that does not include these holes  38 . Both embodiments are contemplated so that greater latitude in adjusting for desired flow rate and/or accounting for type of working fluid is available. 
     In another embodiment, referring to  FIG. 3 , the image is different from  FIG. 2  in that a plug member  40  is illustrated. The plug member  40  is schematically illustrated. It is to be appreciated that the plug member  40  may be a friction fit type surface, a threaded surface, etc. The plug member  40  may be one or more of them and may be installed into the holes  38 . The operator may elect to use one or more of the plug members  40  to adjust the hydrodynamic force that is developed on the closure member  22 , the more plug members  40  the greater the aggregate hydrodynamic force that will act on the closure member  22  from fluid flowing through the opening  34  since reduced fluid flow through holes  38  results in a reduction in the counteracting hydrodynamic force that is created by fluid flowing radially inwardly through the holes  38 . Plug members  40  may be installed in the manufacturing process or on site as desired or required enhancing adjustability of the plug  10 . 
     Referring to  FIG. 4 , another feature employable alone or in combination to control the hydrodynamic force on the closure member  22  is a cover  42 . Cover  42  depending upon its area, shields more or less of the closure member  22  from fluid flowing through the opening  34 . The less area of closure member  22  that is shielded by cover  42 , the higher the hydrodynamic force on the closure member from fluid flowing radially inwardly through the opening  34 . Of course, the reverse is also true, to wit: The greater the area of closure member  22  that is shielded by cover  42 , the lesser the hydrodynamic force on the closure member from fluid flowing radially inwardly through the opening  34 . Cover  42  may be installed in the manufacturing process or on site as desired or required enhancing adjustability of the plug  10 . 
     Referring to  FIG. 5-7 , one exposed to the foregoing will recognize a portion of the plug  10  illustrated (in  FIG. 1 ) and appreciate that an adjusting sleeve  44  is illustrated exploded from its seat area  46 . It is to be appreciated that the adjusting sleeve  44  is to be disposed on its seat area  46  during use and may be placed there during manufacture of the plug  10  or may be placed there on site. The adjusting sleeve  44  is rotatable about the seat area  46  so that one or more ports  48  may be rotationally aligned or misaligned with one or more holes  38  and/or opening  34  of the plug  10 . Alignment and misalignment may be complete or partial so that fine adjustment of hydrodynamic forces acting on the closure member  22  as discussed above is possible simply by rotating the adjusting sleeve  44 . The sleeve  44  is maintained in position axially by shoulders  50  and  52  which may be a part of the plug  10  at the time of manufacture (whereby the sleeve  44  would need to be installed at that time) or may be separate fastenable structures to be assembled in the field such as split shaft collars, threaded collars, collars with radial screws, welded on collars, etc. An alternate sleeve configuration with a wedge shaped port  48   a  is illustrated at  44   a  in  FIGS. 6 and 7  along with a set screw  45  that may be employed in either embodiment. 
     It is also to be appreciated that the assembly  20  or any of the other features disclosed herein in any combination may be installed upon any kind of plug by providing a housing for the assembly  20  and then connecting that housing to a plug by threading, welding, friction fit, etc. 
     In addition to assembly  20  that is maintained selectively in the open position by a magnetic field, it is also contemplated by the inventors hereof that a similar assembly  58  employing a hold open feature  60  such as a spring may be employed instead of the magnetic arrangement (see  FIGS. 8, 9, and 10 ). The hold open feature  60  may be any biasing configuration that is biased to hold the closure member open such as a torsion spring, clock spring, lever spring, coil spring, gas spring, etc. A spring from a safety valve flapper could be used if assembled oppositely to a common assembly for a safety valve to hold the closure member open rather than closed as would be the case in a safety valve. This assembly  58  comprises a hold open spring  60  configured to hold a closure member  62  open against hydrodynamic forces up to a selected threshold hydrodynamic force similar to the foregoing so that certain flow rates are possible without closing the member  62  while at rates above that threshold the member  62  will close. When the hydrodynamic force rises above a threshold force due to fluid flow rate through the plug  10 , the closure member  62  will be forced closed. The hydrodynamic force on the member  62  may be applied thereto identically to the foregoing embodiments or may be added to or substituted by a venturi effect. If a strong venturi effect is desired, a surface  64  of the member  62  exposed to the fluid flow in the borehole the plug  10  may be profiled as a wing to encourage lift on the member  62  in the desired direction (closing) to overcome the hold open capability of the spring  60 . After closure member  62  is closed, the fluid pressure thereagainst in the closing direction will also keep the closure member  62  closed. Upon release of that fluid pressure however, the hold open spring will reset the member  62  to the open position. In another variation of this embodiment, still referring to  FIGS. 8-10 , the closure member  62  may be arranged to be retained in not only the open position but the closed position as well. The closure member  62  in this variation is urged to the open position or to the closed position depending upon where in the range of positions the member  62  is. More specifically, attention is directed to cam member  66 . A portion of the cam member  66  is arranged as a peak  68  with regard to distance from a center axis of a rotation pin  70 . When the closure member  62  is midway between open and closed, the peak  68  has maximally deflected spring  60 . Accordingly, as the member  62  moves in either direction from this maximal deflection, the bias of the spring  60  will assist the closure member  62  to an end point, i.e. open or closed. Hydrodynamic force in either flow direction when of sufficient magnitude will overcome the spring bias and release the closure member toward its other end position. 
     Referring to  FIG. 11 , a wellbore system  72  includes a borehole  74 , a string  76  disposed in the borehole  74  and a plug  10  disposed in the string. The wellbore system  72  may include multiple plugs  10  therein. 
     Set forth below are some embodiments of the foregoing disclosure: 
     Embodiment 1: A plug with a resettable closure member comprising a body defining a flow bore, a closure member movable between a position closing the flow bore and a position wherein the flow bore is open, the closure member responsive to a selected hydrodynamic force to move to the position closing the flow bore and responsive to an attractive magnetic force to move to the position wherein the flow bore is open. 
     Embodiment 2: The plug as in any prior embodiment, wherein the body and closure member comprise components that develop an attractive magnetic force between them, the closure member closing when a hydrodynamic force on the closure member exceeds the attractive magnetic force between the body and closure member. 
     Embodiment 3: The plug as in any prior embodiment, wherein the magnetic force persists when the closure member is in the position closing the flow bore. 
     Embodiment 4: The plug as in any prior embodiment, wherein the closure member is maintainable in the position closing the flow bore by the maintenance of a differential pressure across the closure member. 
     Embodiment 5: The plug as in any prior embodiment, wherein the closure member returns to a position wherein the flow bore is open upon loss of differential pressure across the closure member. 
     Embodiment 6: The plug as in any prior embodiment, wherein the selected hydrodynamic force required to move the closure member to the position closing the flow bore is adjustable by adjusting a strength of the attractive magnetic force between the closure member and the body. 
     Embodiment 7: The plug as in any prior embodiment, wherein adjusting the strength of the attractive magnetic force between the closure member and the body is by adjusting magnetic permeability of at least one of the body and the closure member. 
     Embodiment 8: The plug as in any prior embodiment, wherein adjusting the strength of the attractive magnetic force between the closure member and the body is by disposing magnets on each of the body and the closure member. 
     Embodiment 9: A method for treating a wellbore including flowing a fluid at a rate sufficient to reach the selected hydrodynamic force as in any prior embodiment, closing the closing member, affecting one or more of flow and pressure by the closing of the closure member, resetting the closure member to a position wherein the flow bore is open by reducing at least one of the selected hydrodynamic or pressure to less than the attractive magnetic force. 
     Embodiment 10: The method as in any prior embodiment, wherein the affecting includes increasing the pressure to fracture a formation of the wellbore. 
     Embodiment 11: The method as in any prior embodiment, wherein the affecting includes injecting a treatment into the wellbore. 
     Embodiment 12: A wellbore system including a borehole, a plug as in any prior embodiment, disposed in the borehole. 
     The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Further, it should be noted that the terms “first,” “second,” and the like herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity). 
     The teachings of the present disclosure may be used in a variety of well operations. These operations may involve using one or more treatment agents to treat a formation, the fluids resident in a formation, a wellbore, and/or equipment in the wellbore, such as production tubing. The treatment agents may be in the form of liquids, gases, solids, semi-solids, and mixtures thereof. Illustrative treatment agents include, but are not limited to, fracturing fluids, acids, steam, water, brine, anti-corrosion agents, cement, permeability modifiers, drilling muds, emulsifiers, demulsifiers, tracers, flow improvers etc. Illustrative well operations include, but are not limited to, hydraulic fracturing, stimulation, tracer injection, cleaning, acidizing, steam injection, water flooding, cementing, etc. 
     While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited.