BACKGROUND
In the downhole drilling and completion industry flapper valves have been used for an extended period of time. Such devices are useful whenever it is necessary to cause a fluid to move into the downhole environment from a remote location such as a surface location. Flapper valves come in a number of forms but not uncommonly are configured as tubing retrievable injection valves (TRIV), for example. Such valves often comprise a flapper that articulates and a flow tube that translates through a position occupied by the flapper when closed, thereby maintaining the flapper in an open position throughout the injection cycle. The open position is so maintained by the flow tube structurally pushing the flapper out of the way (causing rotation about its pivot) when the flapper valve is in the open position. While such flapper valves work well for their intended purposes, improvement is always desirable whether that improvement be in performance, cost reduction or both.
SUMMARY
A flapper for a downhole valve including a surface configured to substantially geometrically mate with a tubular section within which the flapper is mounted when in an open position.
A downhole valve including a housing; a flow tube moveably disposed in the housing; and a flapper articulated to the housing, the flapper including a surface configured to substantially geometrically mate with a tubular section within which the flapper is mounted when in an open position.
BRIEF DESCRIPTION OF DRAWINGS
Referring now to the drawings wherein like elements are numbered alike in the several Figures:
FIG. 1 is a schematic view of a flapper valve as disclosed herein in a closed position.
FIG. 2 is a schematic view of the valve of FIG. 1 in an open position.
FIG. 3 is a schematic view of a portion of an alternate embodiment of the flapper valve disclosed herein, the portion circumscribed by line 3-3 in FIG. 2.
FIG. 4 is an alternate embodiment of a flapper valve in a closed position.
FIG. 5 is and alternate embodiment of a flapper valve in an opened position.
DETAILED DESCRIPTION
Referring to FIG. 1, valve 10 such as a flapper valve includes a relatively short flow tube 12 disposed in operable communication with a relatively short housing 14. The flapper valve 10 further includes a flapper 16 articulated to the housing 14 at a pivot point 18. A seal 20 is disposed at the housing 14 and positioned for interaction with the flapper 16 when the flapper valve 10 is in the closed position. More specifically, the seal 20 ensures that the flapper 16 when closed will form a fluid tight interface with the housing 14. Such seals are common and tend to be relatively soft. This makes them vulnerable to flow cutting and hence they require protection. Protection in the illustrated configuration is provided by a flow tube that need be only long enough to extend past the seal 20 when the flapper 16 is open. This is illustrated in FIG. 2. Further, one of ordinary skill in the art will recognize that as illustrated, the flow tube would not function to open the flapper 16 as is the case in many prior art valves but rather stops short of interacting physically with the flapper 16. In this configuration, it is the flow of injection fluid that opens and maintains the flapper 16 in the open position. The flow tube in this configuration then has only to protect the seal 20, which it does in the position illustrated in FIG. 2. It is noted that it is possible to apply the concepts herein to a valve with a longer flow tube that also has function to open the flapper 16 but such function is not necessary to the teaching herein. In either case, an extension spring 22 in operable communication with the flow tube 12 and the housing 14 will automatically move the flow tube 12 to the operational position when the flapper 16 is opened, that opening being due solely to flow or to flow in combination with another opening impetus.
The flapper 16 itself comprises an erosion resistance that is either surface concentrated such as in the form of a coating or a surface layer or may be erosion resistant for a greater percentage of the flapper 16, including but not limited to the entire flapper being composed of erosion resistant material. This configuration allows the use of the valve 10 with high injection flow rates without a flow tube 12 being long enough to cover the flapper 16.
Because the flapper is exposed to flow during use of the valve 10 due to a short flow tube, fluid dynamics considerations are of importance when they are traditionally irrelevant to the flapper. The fluid flowing past and in contact with the flapper 16 causes turbulence behind the flapper 16 adjacent an inside surface 24 of a tubular 26 in which the valve 10 is installed. The turbulence can cause the flapper to move into the flow stream and not stay against the surface 24. This is a hindrance to injection and hence is to be avoided. The problem is exacerbated by higher injection rates. In order to address this issue the inventor hereof has determined that the effect of turbulence with respect to its ability to move the flapper into the injection flow can be minimized by reducing the fluid volume between a surface 28 of the flapper 16 and the surface 24. It is to be noted that the surface 28 may be of the flapper itself or may be of a material attached to the flapper. In one embodiment, the surface 28 is formed by providing a conformable material 30 attached to the flapper 16. The conformable material 30 will assume the shape of the inside surface 24 upon contact therewith and prevent any significant turbulent fluid from urging the flapper 16 away from the surface 24 during injection. This embodiment allows for irregularities in the surface 24 to be accounted for without knowing what those irregularities might be. More specifically, the tubing string in which the valve 10 is installed may have experienced flow cutting or erosion or may have become deformed during run in and resultingly does not necessarily present a cylindrical geometry at the surface 24 for a preconceived surface 28 to geometrically mate with. In such situation a conformable material 30 provides a wider range of functional success in reducing any potential volumes within which turbulent fluids might otherwise act. Conformable materials include but are not limited to rubber, nitrile, foams (including shape memory foam), etc. In other embodiments, the material may be a nonconformable material attached to the flapper or may be the flapper itself. In such cases, the material may geometrically mate well with the inside surface 24 and perform substantially as does the conformable material or may geometrically mate less well with the surface 24 but in any event, the material 30 will be formed to substantially geometrically mate with the surface 24 and accordingly will substantially displace turbulent fluid from the volume defined between the surface 28 and the surface 24. Due to the reduction in turbulent fluid in this location, impetus on the flapper 16 to move into the flow path of the injection fluid is reduced or eliminated.
Still referring to FIGS. 1 and 2, the torsion spring 19 operates to oppose the force of flowing injection fluid but without sufficient energy to overcome the force of the flowing fluid. The flapper 16 then will be opened by the flowing fluid but will close automatically upon cessation of flow of the injection fluid. In one embodiment, the torsion spring is configured with a greater spring force than the extension spring 22 such that the flow tube may be pushed back to its unactuated position by the flapper 16 through the impetus of the torsion spring 18.
In addition to the foregoing, and referring to FIG. 3, the flapper may further include a magnetic component 32 that is attractive to the tubing 26 or to another magnetic component 34 disposed in the tubing 26. The magnet(s) either singly or in combination act to maintain the flapper 16 in contact with the surface 24 thereby reducing any available volume into which fluid may flow which consequently reduces any possible impetus for the flapper 16 to move into the injection flow. In addition, because of the attractive force of the magnets, it is in one embodiment, it is not necessary to have the surface 28 or material 30 of FIGS. 1 and 2. FIGS. 4 and 5 illustrate such an embodiment. With respect to releasing the magnetic attraction of any of the embodiments herein that include magnetic field generating components whether of opposing poles or only one sided and attractive to a ferrous material, a sliding action will be used. For an understanding of such an action and one embodiment of a configuration capable of producing the sliding action, see FIGS. 4 and 5 and the description thereof hereinbelow.
Referring to FIGS. 4 and 5 simultaneously, an embodiment of a flapper valve 100 that ensures the flapper stays in the open position regardless of turbulence is illustrated. Illustrated is a housing 101 having a magnet housing 102 disposed therein. The magnet housing is axially movable within the housing 101 and is fluid sealed thereto by one or more seal 104. The magnet housing 102 supports a magnetic field generating component 106 that comprises a permanent magnet or an electromagnet. The magnet housing 102 is biased by a compression spring 108 that may be a coil spring as illustrated or any other type of spring that provides resilience in compression. The spring 108 is maintained in position by a shoulder 110 in the housing 101 and a flapper sub 112 that bounds the annular space in which the spring 108 is located. The flapper sub 112 is a non movable component that is at least partially composed of a nonmagnetic material, the part being where a magnetic field would need to pass through the sub 112. This area is labeled 115. The sub 112 is anchored by suitable means 114 at recess 116 in housing 101. The suitable means 114 may be one or more fasteners such as threaded fasteners, welding, adhesive, press fit, etc. at an end of flapper sub 112 opposite the means 114 is a pivot 118 and torsion spring 120 that together allow pivotal movement of a flapper 122 and a bias of the flapper 122 to its closed position (illustrated in FIG. 4). Adjacent a portion of the flapper 112 is a flapper seat 124 and a seal 126 thereat. Seat 124 may be attached to flapper sub 112 at and by, for example, thread 128. A flow tube 130 is positioned radially inwardly of the seat 124 and is moveable therein. The flow tube is connected to a tension spring 132 that is also connected to the flapper seat 124. The tension spring 132 tends to bias the flow tube toward the flapper 122 such that when the flapper 122 is in an open position the flow tube will protect the seal 126 from erosion due to fluid flow. The flow tube 130 need merely extend a small distance past the seal to provide this protection. It is to be understood that the tension spring 132 is sufficient in spring rate only to move the flow tube 130 to the protective position but is insufficient to prevent closure of the flapper 122 based upon input from the torsion spring 120. This configuration ensures that the flapper 122 will close properly when it is supposed to without the flow tube interfering with the closure. Finally, the flapper 122 is provided with a magnetic field generating component 136, which in one embodiment comprises a permanent magnet but may be configured as an electromagnet. In one embodiment the exposed surface of the component 136 will be of an opposing magnetic pole to the exposed surface of the component 106. It is inconsequential which one of the two is north or south pole oriented.
In operation, a fluid 138 is applied in the direction of flow arrow 140 toward the flapper valve 100. The fluid 138 forces the flapper to swing open (position depicted in FIG. 5), and simultaneously through fluid drag, moves the magnet housing 102 in the same direction as fluid movement. This action causes the magnetic field generating component 106 to move along with the magnet housing 102 to a position where the arcuate movement of magnetic field generating component 136 will be in register therewith, the movement of component 136 being dependent upon the pivoting movement of flapper 122. Because the two components 106 and 136 are aligned and positioned in proximity to one another as well as being oppositely poled, the flapper is magnetically held in the open position and hence out of the flow of fluid 138. By design the spring force of the torsion spring 120 is insufficient to overcome the magnetic attraction between components 106 and 136 and therefore is of no consequence with respect to maintaining the flapper 122 in the open position. As one of skill in the art will recognize, the flapper of a valve of this type must close when injection is stopped. This action is also unimpeded because as soon as the fluid drag on the magnet housing 102 is relieved, secondary to a pause in the flow of fluid 138, the compression spring 108 will elongate and force the magnet housing 102 to move to the closed position of FIG. 4. This will cause the magnetic field generating component 106 to slide away from the magnetic field generating component 136 thereby substantially reducing the attractive force therebetween. The flapper is hence free to close under the impetus of the torsion spring 120.
In other embodiments, it is noted that the magnetic field generating components need not be on both sides of the resulting attractive interface but rather one could simply be a magnetically responsive material such as a ferrous metal. A reduced attractive force would result but if the component used has a sufficiently potent field, it would still function as noted above. Sliding action would still be used to break the interface wither by moving a nonmagnetic material into proximity with the components while the magnetically responsive material is slidingly moved away or a configuration where a sliding movement would simply position the field generating component farther away from a responsive material such as by sliding one of the structural features described in a direction that allows a recess to be aligned with the filed generating component. In such an embodiment the recess would position a responsive material far enough away from the field generating component to reduce the attractive force to a magnitude less than a closing force supplied by the torsion spring.
While one or more embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.
Patent Application
20110088908
