U.S. patent application number 10/108130 was filed with the patent office on 2003-10-02 for valve system and method.
Invention is credited to Ehlinger, Jeffery C., Smith, Paul L..
Application Number | 20030183398 10/108130 |
Document ID | / |
Family ID | 28452807 |
Filed Date | 2003-10-02 |
United States Patent
Application |
20030183398 |
Kind Code |
A1 |
Smith, Paul L. ; et
al. |
October 2, 2003 |
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.
Inventors: |
Smith, Paul L.; (Katy,
TX) ; Ehlinger, Jeffery C.; (Houston, TX) |
Correspondence
Address: |
GUY E. MATTHEWS
THE MATTHEWS FIRM
STE. 1800
1900 WEST LOOP SOUTH
HOUSTON
TX
77027
US
|
Family ID: |
28452807 |
Appl. No.: |
10/108130 |
Filed: |
March 26, 2002 |
Current U.S.
Class: |
166/387 ;
166/187 |
Current CPC
Class: |
E21B 34/103 20130101;
E21B 23/06 20130101 |
Class at
Publication: |
166/387 ;
166/187 |
International
Class: |
E21B 033/127 |
Claims
What is claimed is:
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.
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.
* * * * *