Valve system and method

Abstract

A system and method for a valve system for downhole use with downhole tools such as packers is disclosed. The valve system includes an opening piston and a closing piston which preferably utilize any suitable means to control erosion such as, for example only, carbide inserts that define the various inlets and outlets of the opening and closing piston. Preferably a carbide baffle is used to produce a slower and smoother fluid pressure flow through the valve system. Pressure from the casing bore above a selected value causes opening piston to shift and permit fluid flow past the valve stem of the closing piston and into the filling port of the packer. When pressure inside the inflatable packer produces a force on the closing piston above a selected amount, the closing piston shifts to the closed position whereby fluid flow into or out of the inflatable packer is prevented. Once pressure is bled off the casing bore, the return spring of the opening piston pushes the piston back to seal off the port. A non-elastomeric seal such as a TEFLON seal and/or an elastomeric seal may be bonded to the closing piston is provided to resist forces that could otherwise damage the seal as the closing piston is shifted to the closed position. An equalizer valve is preferably built into the opening piston equalize hydrostatic pressure to the casing bore.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to downhole valves and, more particularly, to apparatus and methods for downhole valves used with downhole tools such as packers and plugs.

[0003] 2. Description of the Background

[0004] Downhole tools, such as packers, long seal packers, and the like, may be used within a wellbore for many purposes including cementing related operations. In such downhole tools, a valve assembly may be used for inflating or expanding a sealing element.

[0005] Depending on well operations and programs, fluids possibly including abrasive fluids such as cement, maybe pumped through the valve system. However, the rapid flow of fluids and especially abrasive fluids through the valving system may erode and therefore destroy the valve assembly used with downhole tools such as packers and plugs. It would therefore be desirable to provide a valving system for a downhole tool that somehow eliminates or reduces valve system erosion even when abrasive fluids are involved.

[0006] High fluid flow through a valve system can cause other malfunctions of various types. For instance, the valve system sequence of operation may not respond as desired when the fluid flow input is very high. It would be desirable to somehow provide a valve system actuation logic that works reliably for a wide range of fluid flow rates, including pulses of high fluid flow and the like. Another example of valve malfunction caused by high fluid flow rates may occur when a seal on a piston or valve is moved past a port through which high fluid flow occurs, and the seal is damaged. There is a tendency for the seal to be damaged by cutting, wear, or being pulled off the seat surface for the seal as the seal moves past the port.

[0007] Yet other problems with such valve assemblies relate to the fact that the internal packer elements are maintained dry or with little internal fluid to avoid the possibility of bulges caused by internal fluids that might be subject to friction with the casing and result in wear or tearing. However, problems may still occur. For instance, the hydrostatic pressure applied to the outside of the flexible sealing element as the packer is run into the wellbore may act on the valve assembly and cause damage such as breaking shear pins, effecting some sealing against the mandrel, and/or otherwise preventing or inhibiting inflation of the packer.

[0008] U.S. Pat. No. 4,716,963, issued Jan. 5, 1988, to George et al., discloses methods and apparatus for setting a packer and placing a seal assembly into the packer bore on a single trip into the borehole. Such apparatus includes a releaseable mechanism coupling the seal assembly in fixed relation to the packer until such time as the packer is at least partially set. Methods and apparatus include a mechanism for hydraulically setting a packer without any manipulation of the tubing string. A pair of hydraulic pistons are utilized to move in opposite directions and exert forces on both a packer actuating sleeve and the packer body to set the packer. Methods and apparatus are provided for actuating well tools in response to the hydrostatic pressure in the well. Through use of such apparatus, a chamber at atmospheric pressure is placed in communication with one side of a hydraulically moveable member, the other side of which is exposed to hydrostatic pressure.

[0009] While the above patent relates to setting a packer, no teaching is provided for avoiding the erosion damage to downhole valves caused by cement or other fluid-induced abrasion. Moreover, the above prior art does not teach how to prevent damage caused to a seal caused when the seal moves by a port through which fluid flows at a high rate, for instance to thereby close off the port. Consequently, it would be desirable to provide means that limit damage to valves that may be in packers, long packers, or other downhole tools. Those skilled in the art have long sought and will appreciate the present invention which provides solutions to these and other problems.

SUMMARY OF THE INVENTION

[0010] The present invention was designed to provide an improved valve system for downhole tools.

[0011] Another object of the present invention is to provide a more durable and reliable downhole valve system.

[0012] These and other objects, features, and advantages of the present invention will become apparent from the drawings, the descriptions given herein, and the appended claims.

[0013] Therefore, the present invention provides for a valve system for a downhole tool comprising elements such as, for instance, a valve body, an opening valve assembly within the valve body, and an opening piston for the opening valve assembly wherein the opening piston may be moveable in response to pressure acting thereon from a closed position to an open position to permit fluid flow through a flow path through the valve body. A closing valve assembly may also be provided within the valve body. The flow path extends through the closing valve assembly when the opening piston is in the open position.

[0014] In a presently preferred embodiment, a sleeve surrounds the opening valve assembly. Moreover, the valve body preferably defines a machined aperture such that the sleeve slidably fits more precisely into the aperture. As well, a sleeve preferably surrounds the closing valve assembly.

[0015] To limit rapid fluid flow, an impedance is provided to oppose or slow fluid flow. In a preferred embodiment, a baffle assembly is provided which has a plurality of walls therein. Each of the plurality of walls defines a one or more openings.

[0016] The valve system may preferably be configured so that the flow path through the closing port extends around a closing piston valve stem. The closing piston is moveable to close the flow path if the inflated element is full and pressure acts on the end of the piston. A seal may be bonded to the closing valve piston to prevent damage thereto when the closing piston closes. In a preferred embodiment, the seal further comprises at least one non-elastomeric seal on the closing piston.

[0017] A valve is provided to let pressure into the inflated element to equalize internal element pressure to the annulus pressure.

[0018] In operation, the method may comprise steps such as applying pressure to an opening piston for moving the opening piston from an original position to a shifted position to thereby open a flow path through the valve system for filling the inflatable element, and connecting internal pressure from the inflatable element of the downhole tool to a closing piston such that the closing piston moves from an original position to a closed position after the internal pressure reaches a selected pressure. The movement of the closing piston may preferably close the flow path to prevent further fluid flow into the inflatable element.

[0019] Other steps may include biasing the opening piston such that the opening piston moves back to the original position by reducing the applied pressure, and locking the opening piston in the original position.

[0020] In a presently preferred embodiment, a step of shearing a shearable member occurs in response to the step of applying pressure to permit movement of the opening piston. Other steps may include impeding fluid flow into the fluid flow path with a baffle or providing that the flow path extends through the closing valve assembly such that after the opening piston moves, fluid flow occurs through the flow path into the inflatable element.

[0021] A method for making a valve system for a downhole tool with an inflatable element may comprise steps such as providing a valve body with a first cylinder for an opening piston wherein the opening piston may be moveable between an open position and a closed position for controlling fluid flow for the inflatable element. Other steps may include providing the valve body with a second cylinder for a closing piston such that the closing piston may be moveable between an open position and a closed position for controlling fluid flow for the inflatable element, inserting a first cylinder liner in the valve body around the opening piston, and inserting a second cylinder liner in the valve body around the closing piston.

[0022] The method includes providing ports through the first cylinder liner and the second cylinder liner or machining the first cylinder and the second cylinder in the valve body for receiving the first cylinder liner and the second cylinder liner, respectively.

[0023] In one embodiment of the present invention, the valve system for the downhole tool may comprise elements such as, for instance, a valve body having a fluid flow path therethrough, a valve assembly disposed within the valve body, and a baffle assembly for the valve body. The baffle assembly may comprise a plurality of walls spaced apart and secured with respect to each other. The plurality of walls define one or more ports. The baffle assembly receives fluid flow for the fluid flow path for such purposes as limiting and/or impeding fluid flow and/or smoothing fluid flow through he valve system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 is a perspective view, partially in section, of a valve system with insert sleeves shown in accord with the present invention;

[0025] FIG. 2 is a perspective view, partially in section, of the valve system of FIG. 1 in the initial installed valve position;

[0026] FIG. 3 is a perspective view, partially in section, of the valve system of FIG. 1 in the initial installed valve configuration;

[0027] FIG. 4 is a perspective view, partially in section, of the valve system in the inflating valve configuration;

[0028] FIG. 5 is a perspective view, partially in section, of the valve system in the closed and locked valve configuration;

[0029] FIG. 6 is a perspective view, partially in section, that shows an equalizer valve within the opening valve piston;

[0030] FIG. 7 is a schematic view showing a diagram for a baffle arrangement in accord with the present invention; and

[0031] FIG. 8 is an elevational view shown a packer set within the wellbore casing in accord with the present invention.

[0032] While the present invention will be described in connection with presently preferred embodiments, it will be understood that it is not intended to limit the invention to those embodiments. On the contrary, it is intended to cover all alternatives, modifications, and equivalents included within the spirit of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Referring now to the drawings and more specifically to FIG. 1 through FIG. 6, there is shown a valve system 10 in accord with the present invention. As discussed in detail hereinafter, the valve system of the present invention uses an improved actuation logic based on fluid moving through an inlet, around a closing valve stem, and then exiting through an outlet instead of through the valve.

[0034] A typical packer arrangement, such as packer arrangement 11 is shown in FIG. 8 within wellbore 15 and may include slips 17 and expandable member 19. Expandable member 19 may be expanded to set packer arrangement 11 within the casing, tubular string, and the like which may be found within wellbore or tubular string 15 by means of fluid flow controlled by valve system 10. For instance packer 11 may provide a seal between tubular string 23 and outer tubular string 15 such as a casing string.

[0035] In one aspect of the invention, there is preferably provided hardened insert sleeves 12 to thereby protect valve body 14, shown split for convenience in viewing, from erosion due to fluid abrasion as shown in FIG. 1. In FIG. 2 and FIG. 3, valve assemblies 18 and 20 are shown with insert sleeves 12 and 13 cut away. Insert sleeves 12 and 13 fit into valve body cylinders 16 and 21, respectively. Valve body cylinders 16 and 21 are preferably machined into valve body 14 to provide for a close tolerance fit. Another advantage of insert sleeves 12 and 13 is that they may conveniently be used to control port size, cross port location, and port finish quality in a manner that is much less expensive than attempting to machine valve body 14 to provide this function. The various ports are discussed subsequently. Valve assembly 18 is the opening valve and valve assembly 20 is the closing valve. Valve assemblies 18 and 20 preferably utilize carbides or hardened steel or other suitable erosion resisting materials to provide piston components with minimized wear due to abrasion. Screw members 22 and 24 may be threaded into valve body 14 not further than the depth provided by shoulders 26 and 28, respectively. Preferably snap-on retainer rings 30 and 32 mounted to screw members 22 and 24 and shim members 31 and 33 may then be used to properly position the relative spacing of the components within valve assemblies 18 and 20 and also with respect to valve body 14. Spring 35 is preferably a stainless steel garter spring used to provide bias to thereby lock the opening piston in a sealed position as discussed subsequently. Shear pins 34 and 36 secure the valve components in position after assembly and during running of the downhole tool into the wellbore. In one embodiment, shear pins 34 and 36, or breakable plugs, screws, or other breakable elements may be selectively broken within a desired operating sequence to effect operation of valve system 10 as discussed subsequently. Other pressure operated means could be used that effectively are actuated in response to pressure that increases above a selected level.

[0036] Fluid controlled by opening valve 18 enters through port 38. In a preferred embodiment fluid control is provided before fluid reaches port 38 in a unique manner by use of a baffle arrangement, such as baffle arrangement 40 shown conceptually in FIG. 7. Baffle arrangement 40 may preferably include up to three or more wall members, such as wall members 42, 44, and 46 with openings or holes staggered relative to each stacked member such that slurry or cement flow into opening valve 18 through port 38 is retarded, restricted, or impeded to slow fluid flow therethrough and so prevent or reduce erosion. Thus, ports 48, 50, and 52 may be staggered with respect to each other to thereby impede fluid flow. Flow into baffle 40 may be through port 53 whereupon flow continues through baffle 40 to exit baffle 40 through port 38 and into valve assembly 10. Baffle arrangement 40 is preferably formed substantially or entirely with carbide components. Baffle 40 may be formed as part of valve housing 14, may be attached to valve housing, or may be separated from valve housing 14 with a conduit leading thereto.

[0037] In the initial position, as per FIG. 1-FIG. 3, opening piston 54 provides seals 58 and 60 that seal off filling fluid flow port 62. Seals 58 and 60 may each comprise one or more seals, as desired. Note that the size and shape of ends 64 and 66 of flow port 62 are defined by insert sleeves 12 and 13. As shown in FIG. 4, fluids pressure due to fluid flow through baffle 40 to inlet 38 acts on opening piston 54. As the pressure increases, force applied to opening piston 54 overcomes return spring 56 and to shear pin 34 such that opening piston pin 68 is freed to move outwardly after shear pin 34 breaks. In other words, pressure from casing bore 15 against sealed face area 70 of opening piston 54 produces force up to the shear rating of shearing pin 34 installed in opening piston pin 68. This allows opening piston 54 to shift, permitting inflation fluid flow through valve system 10 passing through valve system outlet port or fill port 74 and thus into expandable packer element 19 (see also FIG. 8). Flow arrows 72 disclose the flow path.

[0038] It will be noted that fluid flow proceeds around closing valve stem 76 which is in the initial position during filling. Thus, fluid flow is directed around the initial position of closing valve stem 76 rather than past seals or ports uncovered by closing valve assembly. Forces acting between seal 78 and seal 80 of closing stem 76 are equal and opposing so that premature closing of valve assembly 20 is prevented regardless of pressure acting along flow path 72 while fluid inflates the packer.

[0039] Pressure inside of packer 11 produces a force on sealed end face area 84 of closing piston 86, by means of pressure at limit port 77 which connects to the interior of inflatable element19. When the pressure at limit port 77 becomes equal to the shear rating of shearing pin 36 of closing piston pin 82, then closing piston 86 shifts into the closed position indicated in FIG. 5. Thus, filling fluid flow passageway 72 is blocked. As pressure is bled from casing bore 15, return spring 56 pushes opening piston 54 back to seal off port 88. Piston lock 90 which is activated by garter spring 35 may be used to prevent opening piston 54 from opening again.

[0040] As closing piston 86 moves to the closed position, seal 80 is moved by outlet port 74. Seal 80 is preferably a non-elastomeric seal, such as a Teflon seal or other non-elastomer. In a preferred embodiment, seal 80 is not bonded to the piston. However, seal 80 could be bonded to closing piston 86 such as by glue, heating, or any other method of bonding to thereby permanently affix seal 80 to closing piston 86 such that seal 80 cannot be removed or pulled off of closing piston 86, if desired. An elastomer O-ring seal would be subject to significant damage and possibly being torn off as the seal moves past outlet or fill port 74. However in a preferred embodiment, an elastomer O-ring seal 81 may also be provided directly adjacent to seal 80 on piston 86. In a preferred embodiment, seal 81 maybe bonded in position by any suitable means. An elastomer O-ring seal 81 easily and conveniently forms a good seal, but is subject to many problems such as abrasion, tearing, temperature and the like. While a non-elastomer or Teflon seal 80 is less subject to tearing, abrasion, temperature problems, is resistant to acidic and corrosive materials, and has other good properties, a non-elastomer or Teflon seal is more difficult to provide good sealing. Therefore, the combination seal arrangement of non-elastomer seal 80 with an elastomer seal 81 may significantly improve both the sealing and the reliability of the seal arrangement.

[0041] FIG. 6 shows equalizer valve 91 which may include ball 92, spring 94, and seat 96. Hole 93 provides entry into opening piston 54.

[0042] Equalizer valve 91 may be positioned within opening piston 54 to form a flow passageway there through hole 97 into equalizer valve 91 out through hole 93 into fill port 74 to allow for hydrostatic pressure equalization inside the inflation element 19 of packer 11 to casing bore 15.

[0043] Thus in summary of a presently preferred embodiment of the actuation logic of the present invention, to effect opening or setting of packer 11 pressure from casing bore 15 against sealed face area 70 of opening piston 54 produces force up the shear rating of shearing pin 34 installed in opening piston pin 68. Equal opposing force due to pressure on stem portion 76 of closing piston 86 prevents premature closing of closing piston 86 while fluid inflates inflatable element 19 of packer 11. When pressure inside of inflatable element 19 produces a force on sealed end face area 84 of closing piston 86 due to the fluid connection to internal element 19 with limiting port 77 that is equal to shear rating on pin 36 of closing piston pin 82, then closing piston 86 shifts to the closed position as indicated in FIG. 5. When pressure is bled from casing bore 15, return spring 56 of opening piston 54 pushes opening piston 54 back to seal off port 88. Piston lock mechanism 90 now locks opening piston 54 in position to prevent opening piston 54 from reopening.

[0044] The inserts and/or other valve components are preferably hardened by any suitable means and may comprise hardened steel, carbide, one or more hardened coatings, ceramic materials, and the like.

[0045] Therefore, the foregoing disclosure and description of the invention is illustrative and explanatory thereof, and it will be appreciated by those skilled in the art, that various changes in the size, shape and materials, the use of mechanical equivalents, as well as in the details of the illustrated construction or combinations of features of the various elements maybe made without departing from the spirit of the invention.

Claims

1. A valve system for a downhole tool, comprising:

a valve body;

an opening valve assembly within said valve body, said opening valve assembly having an opening piston, said opening piston being moveable from a closed position to an open position in response to pressure acting thereon to open a flow path through said valve body; and

a closing valve assembly within said valve body, said flow path extending through said closing valve assembly when said opening piston is in said open position.

2. The valve system of claim 1, further comprising:

a sleeve surrounding said opening valve assembly.

3. The valve system of claim 1, further comprising:

said valve body defining a machined aperture, said sleeve slidably fitting into said aperture.

4. The valve system of claim 1, further comprising:

a sleeve surrounding said closing valve assembly.

5. The valve system of claim 1, further comprising:

a baffle having a plurality of walls therein, each of said plurality of walls defining a one or more openings.

6. The valve system of claim 1, wherein said flow path through said closing piston extends around a closing piston valve stem.

7. The valve system of claim 1, wherein:

said closing piston is moveable to close said flow path.

8. The valve system of claim 1, further comprising a seal bonded to said closing piston.

9. The valve system of claim 1, further comprising a non-elastomeric seal on said closing piston.

10. The valve system of claim 1, further comprising an elastomeric seal on said closing piston adjacent said non-elastomeric seal.

11. The valve system of claim 1, further comprising:

an equalizer valve mounted within said opening piston.

12. A method for a valve system for a downhole tool with an inflatable element, said method comprising:

applying pressure to an opening piston for moving said opening piston from an original position to a shifted position to thereby open a flow path through said valve system for filling said inflatable element; and

connecting internal pressure from said inflatable element of said downhole tool to a closing piston such that said closing piston moves from an original position to a closed position after said internal pressure reaches a selected pressure, said movement of said closing piston closing said flow path to prevent further fluid flow into said inflatable element.

13. The method of claim 12, further comprising:

biasing said opening piston such that said opening piston moves back to said original position by reducing said applied pressure, and

locking said opening piston in said original position.

14. The method of claim 12, further comprising:

shearing a shearable member in response to said step of applying pressure to permit movement of said opening piston.

15. The method of claim 12, further comprising:

bonding a sealing element to said closing piston.

16. The method of claim 12, further comprising:

providing a non-elastomer as a sealing element of said closing piston.

17. The method of claim 12, further comprising:

providing an elastomeric adjacent said non-elastomer sealing element.

18. The method of claim 12, further comprising:

equalizing pressure inside said inflatable element to a wellbore.

19. The method of claim 12, further comprising:

impeding fluid flow into said fluid flow path with a baffle.

20. The method of claim 12, further comprising:

providing said flow path through said closing valve assembly such that after said opening piston moves, then fluid flow occurs through said flow path into said inflatable element.

21. A method for a valve system for a downhole tool with an inflatable element, said method comprising:

providing a valve body with a first cylinder for an opening piston, said opening piston being moveable between an open position and a closed position for controlling fluid flow for said inflatable element;

providing said valve body with a second cylinder for a closing piston, said closing piston being moveable between an open position and a closed position for controlling said fluid flow for said inflatable element;

inserting a first cylinder liner in said valve body around said opening piston, and

inserting a second cylinder liner in said valve body around said closing piston.

22. The method of claim 21, further comprising:

providing ports through said first cylinder liner and said second cylinder liner.

23. The method of claim 21, further comprising:

machining said first cylinder and said second cylinder in said valve body for receiving said first cylinder liner and said second cylinder liner, respectively.

24. The method of claim 21, further comprising:

bonding a sealing element to said closing piston.

25. The method of claim 21, further comprising:

providing a non-elastomer as a sealing element of said closing piston.

26. The method of claim 21, further comprising:

providing a plurality of walls with offset openings therebetween for impeding said fluid flow into said valve body.

27. The method of claim 21, further comprising:

providing said flow path through said closing valve assembly such that when said opening piston is in said open position, then said fluid flow occurs through said flow path into said inflatable element.

28. The method of claim 21, further comprising:

providing a locking assembly for locking said opening position in said closed position after said inflatable element is inflated.

29. The method of claim 21, further comprising:

forming a equalizing valve in said opening position to permit said fluid flow through said opening piston when said opening piston is in said closed position.

30. A valve system for a downhole tool, comprising:

a valve body, said valve body having a fluid flow path therethrough;

a valve assembly disposed within said valve body;

a baffle assembly for said valve body, said baffle assembly comprising a plurality of walls spaced apart and secured with respect to each other, said plurality of walls defining one or more ports, said baffle assembly receiving fluid flow for said fluid flow path.

31. The valve system of claim 30, wherein said valve assembly disposed within said valve body further comprises:

an opening valve assembly within said valve body, said opening valve assembly having an opening piston, said opening piston being moveable in response to pressure acting thereon from a closed position to an open position to open a flow path through said valve body; and

a closing valve assembly within said valve body, said flow path extending through said closing valve assembly when said opening piston is in said open position.

32. The valve system of claim 31, further comprising:

a sleeve surrounding at least one of said opening valve assembly or said closing valve assembly.

33. The valve system of claim 31, wherein said flow path through said closing piston extends around a closing piston valve stem.

34. The valve system of claim 31, wherein:

said closing piston is moveable in response to pressure acting thereon to close said flow path.

35. The valve system of claim 31, further comprising a seal bonded to said closing valve piston.

36. The valve system of claim 31, further comprising a non-elastomeric seal on said closing piston.

37. The valve system of claim 31, further comprising:

an equalizing valve mounted within said opening piston.

38. The valve system of claim 31, further comprising:

said valve body defining a machined aperture, and

a sleeve slidably fitting into said aperture.

39. The valve system of claim 31, wherein said baffle assembly receives said fluid flow prior to said fluid flow entering said fluid flow path through said valve body.

40. A valve system for a downhole tool controlling fluid flow to an expandable member, comprising:

a valve body;

at least one valve assembly within said valve body, said at least one valve assembly having at least one piston; and

at least one non-elastomer seal disposed on said at least one piston.

41. The valve system of claim 40, further comprising:

an elastomer seal adjacent said non-elastomer seal.

42. The valve system of claim 41, further comprising:

at least one of said elastomer seal or said non-elastomer seal being bonded to said at least one piston.

43. The valve system of claim 40, further comprising:

an opening valve assembly with an opening piston within said valve body,

a closing valve assembly with a closing piston within said valve body, said non-elastomer seal being provided on said closing piston.

44. The valve system of claim 43, further comprising:

said flow path extending through said closing valve assembly when said opening piston is in said open position.

45. The valve system of claim 44, further comprising hardened sleeves insertable into said valve body to resist erosion due to said fluid flow.

46. The valve system of claim 44, wherein said opening valve assembly and said closing valve assembly are hardened to resist erosion due to said fluid flow.