U.S. patent application number 12/739063 was filed with the patent office on 2010-12-02 for valve assembly.
Invention is credited to Davidson Harman, Damien Gerard Patton.
Application Number | 20100301242 12/739063 |
Document ID | / |
Family ID | 38858206 |
Filed Date | 2010-12-02 |
United States Patent
Application |
20100301242 |
Kind Code |
A1 |
Patton; Damien Gerard ; et
al. |
December 2, 2010 |
VALVE ASSEMBLY
Abstract
A valve assembly (10) comprises a conduit having a throughbore
(19) and defining a longitudinal axis, a sealing member (20) that
is moveable between an open configuration in which the throughbore
(19) of the conduit is open, and a sealing configuration in which
the sealing member (20) is arranged to substantially obturate the
throughbore of the conduit, wherein in the sealing configuration,
the sealing member (20) seals the throughbore (19) along a sealing
line at least a part of which is angled relative to a direction
perpendicular to the axis of the throughbore (19).
Inventors: |
Patton; Damien Gerard;
(Huntly, GB) ; Harman; Davidson; (Aberdeen,
GB) |
Correspondence
Address: |
WINSTEAD PC
P.O. BOX 50784
DALLAS
TX
75201
US
|
Family ID: |
38858206 |
Appl. No.: |
12/739063 |
Filed: |
November 5, 2008 |
PCT Filed: |
November 5, 2008 |
PCT NO: |
PCT/GB08/51030 |
371 Date: |
June 14, 2010 |
Current U.S.
Class: |
251/129.01 ;
251/298 |
Current CPC
Class: |
E21B 34/06 20130101;
F16K 15/03 20130101; Y10T 137/86389 20150401; E21B 34/10
20130101 |
Class at
Publication: |
251/129.01 ;
251/298 |
International
Class: |
F16K 31/02 20060101
F16K031/02; F16K 1/16 20060101 F16K001/16 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 6, 2007 |
GB |
0721746.6 |
Claims
1. A valve assembly comprising: a conduit having a throughbore and
defining a longitudinal axis; a sealing member that is moveable
between an open configuration in which the throughbore of the
conduit is open and a sealing configuration in which the sealing
member is arranged to substantially obturate the throughbore of the
conduit; and wherein in the sealing configuration, the sealing
member seals the throughbore along a sealing line at least a part
of which is angled relative to a direction perpendicular to the
longitudinal axis of the throughbore.
2. A valve assembly as claimed in claim 1, wherein the shape of the
sealing line is non-planar.
3. A valve assembly as claimed claim 1, wherein the sealing member
is both pivotally and axially moveable between the open
configuration and the sealing configuration.
4. A valve assembly as claimed in claim 1, wherein at least one
face of the sealing member is curved around the longitudinal axis
of the throughbore when in the open configuration.
5. A valve assembly as claimed in claim 4, wherein the curve of the
at least one face of the sealing member around the longitudinal
axis comprises a substantially constant radius.
6. A valve assembly as claimed in claim 1, wherein the sealing
member comprises a convex face and the sealing line is arranged
along the convex face of the sealing member.
7. A valve assembly as claimed in claim 1, wherein an outer edge of
the sealing member is shaped to conform to an inner surface of the
conduit.
8. A valve assembly as claimed in claim 1, wherein the sealing
member is substantially spade shaped in plan.
9. A valve assembly as claimed in claim 1, wherein in the sealing
configuration, the sealing member substantially obturates the
throughbore to restrict passage of fluids therethrough and retains
pressure across the seal in at least one direction.
10. A valve assembly as claimed in claim 9, wherein the valve
assembly retains pressure across the seal in both directions.
11. A valve assembly as claimed in claim 1, wherein the sealing
line is arranged along an upstream face of the sealing member.
12. A valve assembly as claimed in claim 1, wherein the sealing
member comprises part of a sealing mechanism selectively actuable
to move the sealing member between the open configuration and the
sealing configuration.
13. A valve assembly as claimed in claim 12, wherein the sealing
member is pivotally coupled to the sealing mechanism and is
pivotally movable within the bore.
14. A valve assembly as claimed in claim 13, wherein the sealing
member is pivotable through less than 90.degree. of rotation to
move between the open configuration and the sealing
configuration.
15. A valve assembly as claimed in claim 14, wherein the sealing
member is pivotable through about 45.degree. of rotation to move
between the open configuration and the sealing configuration.
16. A valve assembly as claimed in claim 13, wherein the sealing
mechanism is actuable to cause axial movement of the sealing
member.
17. A valve assembly as claimed in claim 13, wherein the sealing
member comprises pivotally attached first and second portions and
the first portion is movable only in an axial direction, wherein
the second portion is movable axially due to its attachment to the
first portion as well as pivotally through pivot of the second
portion relative to the first portion.
18. A valve assembly as claimed in claim 1, further comprising a
valve seat provided in the throughbore of the conduit, wherein the
valve seat is arranged such that the sealing member seals against
the valve seat in the sealing configuration.
19. A valve assembly as claimed in claim 18, wherein the valve
assembly further comprises a second valve seat for selective
sealing against the sealing member.
20. A valve assembly as claimed in claim 19, wherein at least one
of the first and second valve seats moves relative to the sealing
member.
21. A valve assembly as claimed in claim 19, wherein the second
valve seat is shaped to guide the sealing member towards the
sealing configuration.
22. A valve assembly as claimed in claim 18, wherein the first
valve seat is mounted on an end face of a sleeve that is axially
moveable within the bore of the conduit.
23. A valve assembly as claimed in claim 1, wherein the valve
assembly is resettable in that it is repeatably moveable between
the open and sealing configurations.
24. A valve assembly as claimed in claim 23, wherein the valve
assembly comprises a reset system, the actuation of which can cause
movement of the valve assembly from the sealing configuration to
the open configuration.
25. A valve assembly as claimed in claim 24, wherein the reset
system is responsive to at least one of the following means
selected from the group consisting of: a timer; a radio frequency
signal: a pressure pulse; a mechanical driving means; and
electromagnetic induction, for selective movement of the valve
assembly into a predetermined configuration.
26. A self-cleaning flapper valve assembly as claimed in claim 1,
wherein the flapper valve assembly and at least one valve seat is
shaped such that movement of the sealing member from the open into
the sealing configuration cleans the valve seat.
27. A self-cleaning flapper valve assembly as claimed in claim 26,
wherein the self-cleaning action is achieved by contact between the
sealing member and the valve seat as the sealing member is moved
into the sealing configuration, since the moving contact between
the sealing member and the valve seat can scrape debris from the
valve seat.
28. A valve assembly comprising: a conduit with a throughbore for
passage of fluid therethrough; and a sealing member that is both
pivotally and axially moveable between an open configuration in
which the throughbore of the conduit is open and a sealing
configuration in which the sealing member is arranged to
substantially obturate the throughbore of the conduit.
29. (canceled)
Description
[0001] The present invention relates to a valve assembly. In
particular, though not exclusively, the invention relates to a
flapper valve assembly.
[0002] Flapper valves are widely used in fluid conduits that
transfer fluids between an oil or gas reservoir and a wellhead.
Flapper valves are typically hinged at one side of the conduit and
pivotable in an arc 90.degree. about the hinge to move between an
open and a closed configuration. In the open configuration, the
valve is disposed generally parallel to the longitudinal axis of
the throughbore of the conduit and is therefore removed from the
throughbore to allow fluids to flow therethrough. In the closed
configuration, the valve lies perpendicular to the longitudinal
axis of the throughbore to obturate the bore of the conduit.
However, conventional flapper valves have the disadvantage that
they are unidirectional i.e. they only seal and hold pressure in
one direction.
[0003] According to a first aspect of the present invention there
is provided a valve assembly comprising:
[0004] a conduit having a throughbore and defining a longitudinal
axis;
[0005] a sealing member that is moveable between an open
configuration in which the throughbore of the conduit is open and a
sealing configuration in which the sealing member is arranged to
substantially obturate the throughbore of the conduit;
[0006] wherein in the sealing configuration, the sealing member
seals the throughbore along a sealing line at least a part of which
is angled relative to a direction perpendicular to the longitudinal
axis of the throughbore.
[0007] The shape of the sealing line can be non-planar.
[0008] According to a second aspect of the invention, there is
provided a valve assembly comprising:
[0009] a conduit with a throughbore for the passage of fluid
therethrough; and
[0010] a sealing member that is both pivotally and axially moveable
between an open configuration in which the throughbore of the
conduit is open and a sealing configuration in which the sealing
member is arranged to substantially obturate the throughbore of the
conduit.
[0011] According to the second aspect of the invention, the sealing
member can seal the throughbore along a sealing line at least a
part of which is angled relative to a direction perpendicular to a
longitudinal axis of the throughbore.
[0012] Preferably, the sealing member is non-circular in plan and
preferably is longer than it is wider. The sealing member can be
non-planar. More preferably, the sealing member can be arcuate. At
least one face of the sealing member can be curved around the
longitudinal axis of the throughbore and more preferably a central
axis of the sealing member is arranged to be parallel to the
longitudinal axis of the throughbore, when in the open
configuration. The curve of the at least one face of the sealing
member around the longitudinal axis can have a substantially
constant radius. A sealing member having such a shape can take up
less space and thus improve space efficiency of the apparatus when
the sealing member is in the open configuration.
[0013] The sealing member can have a convex face and the sealing
line can be arranged along the convex face of the sealing
member.
[0014] The sealing member can be substantially spade, teardrop or
egg-shaped in plan view.
[0015] An outer edge of the sealing member can be shaped to conform
to an inner surface of the conduit.
[0016] According to a third aspect of the present invention, there
is provided a valve assembly comprising:
[0017] a conduit with a throughbore for the passage of fluid
therethrough; and
[0018] a sealing member for selectively opening and sealing the
throughbore, wherein the sealing member is substantially spade
shaped in plan.
[0019] According to the third aspect of the invention, the sealing
member can be movable between an open configuration and a sealing
configuration.
[0020] In the open configuration, the throughbore is open allowing
passage of fluids therethrough. In the sealing configuration, the
sealing member substantially obturates the throughbore to restrict
passage of fluids therethrough.
[0021] In the sealing configuration, the valve assembly can retain
pressure across the seal in one direction. More preferably, the
valve assembly can retain pressure across the seal in both
directions.
[0022] The sealing member preferably seals the throughbore along a
sealing line that is angled relative to a direction perpendicular
to an axis of the throughbore.
[0023] Typically fluids predominantly flow through the conduit in
one direction. The sealing line can be arranged along an upstream
face of the sealing member.
[0024] According to any aspect of the invention, the sealing member
preferably forms part of a sealing mechanism selectively actuable
to move the sealing member between the open configuration and the
sealing configuration.
[0025] The sealing member can be pivotally coupled to the sealing
mechanism and more preferably can be pivotally movable within the
bore.
[0026] The sealing member can be pivotable through less than
90.degree. of rotation to move between the open configuration and
the sealing configuration. More preferably, the sealing member is
pivotable through less than 70.degree. of rotation to move between
the open configuration and the sealing configuration. More
preferably, pivotal movement of the sealing member of less than
50.degree. and most preferably around 45.degree. allows the sealing
member to move between the open and the sealing configuration.
[0027] The sealing mechanism can also be actuable to cause axial
movement of the sealing member.
[0028] Movement of the sealing member between the open
configuration and the sealing configuration is preferably actuated
by both axial and pivotal movement of the sealing member.
[0029] The sealing member can comprise pivotally attached first and
second portions. The first portion can be movable only in an axial
direction. The second portion can be movable axially due to its
attachment to the first portion as well as pivotally through pivot
of the second portion relative to the first portion.
[0030] The sealing mechanism can be hydraulically actuable and is
preferably coupled to a hydraulic actuation system.
[0031] A valve seat can be provided in the throughbore of the
conduit. The valve seat can be arranged such that the sealing
member seals against the valve seat in the sealing
configuration.
[0032] The valve seat can be shaped to conform with the profile of
the sealing member along the sealing line. The sealing line is
preferably the line along which the valve seat and the sealing
member are in contact when in the sealing configuration.
[0033] Alternatively, the sealing line can be the line along which
a seal is made between an inner surface of the conduit and the
sealing member.
[0034] The valve seat can be moveable between a stowed
configuration and a spaced configuration. In the stowed
configuration, the sealing member engages the valve seat when the
sealing member is in the sealing configuration. In the spaced
configuration, the sealing member is spaced from and movable
relative to the valve seat.
[0035] The valve assembly can further comprise a second valve seat
for selective sealing against the sealing member.
[0036] At least one of the first and second valve seats can move
relative to the sealing member. The sealing member can typically
seal against at least one of the valve seats in the sealing
configuration. The sealing member can seal against both of the
valve seats in the sealing configuration.
[0037] The second valve seat can be shaped to guide the sealing
member towards the sealing configuration. The second valve seat is
preferably shaped to conform with the profile of the sealing member
along the sealing line.
[0038] The first valve seat can be axially moveable within the
bore.
[0039] The first valve seat can be mounted on an end face of a
sleeve that is slideable within the bore of the conduit.
[0040] The sleeve is preferably hydraulically operable. The sleeve
can be hydraulically coupled to the hydraulic actuation system also
used to open the sealing mechanism.
[0041] The hydraulic system of the valve assembly can be actuable
by at least one of the following means selected from the group
consisting of: a timer; radio frequency signals; a pressure pulse;
and electromagnetic induction.
[0042] Alternative methods of actuation of the sealing mechanism
include applied pressure using control lines and mechanically
driven means, such as different types of motor.
[0043] The valve assembly is preferably resettable in that it is
preferably repeatably moveable between the open and sealing
configurations. The valve assembly can comprise a reset system, the
actuation of which can cause movement of the valve assembly from
the sealing configuration to the open configuration.
[0044] Where the valve assembly incorporates a reset system, the
reset system can be responsive to at least one of the following
means selected from the group consisting of: a timer; a radio
frequency signal: a pressure pulse; a mechanical driving means; and
electromagnetic induction, for selective movement of the valve
assembly into a predetermined configuration.
[0045] The valve assembly can be a flapper valve assembly. The
sealing member of the valve assembly can be a flapper.
[0046] According to a fourth aspect of the invention, there is
provided a flapper valve assembly comprising:
[0047] a conduit having a throughbore and a flapper valve; and
[0048] wherein the flapper valve is pivotable through less than
90.degree. to seal the throughbore.
[0049] According to a fifth aspect of the invention there is
provided a self-cleaning flapper valve assembly.
[0050] The self-cleaning flapper valve assembly can comprise: a
flapper valve selectively moveable between an open configuration
and a sealing configuration; and at least one valve seat against
which the flapper valve can seal to substantially seal the
throughbore. The flapper valve and the at least one valve seat can
be shaped such that movement of the sealing member from the open
into the sealing configuration cleans the valve seat.
[0051] The self-cleaning action can be achieved by contact between
the sealing member and the valve seat as the sealing member is
moved into the sealing configuration, since the moving contact
between the sealing member and the valve seat can scrape debris
from the valve seat.
[0052] Optional and essential features of the first, second and
third aspects of the invention can also be incorporated with
features of the fourth and fifth aspects of the invention where
appropriate.
[0053] Embodiments of the present invention will now be described,
by way of example only, and with reference to the accompanying
drawings, in which:--
[0054] FIGS. 1a and 1b are, respectively, a partial cutaway plan
view and a sectional view of a valve assembly in its open
configuration;
[0055] FIG. 1c is an end view of the valve assembly of FIG. 1a;
[0056] FIGS. 2a and 2b are, respectively, a partial cutaway plan
view and a sectional view of the valve assembly of FIGS. 1a and 1b
showing the sealing member exposed in its open configuration;
[0057] FIGS. 3a and 3b are, respectively, a partial cutaway plan
view and a sectional view of the valve assembly of FIGS. 1a and 1b
but showing the sealing member substantially obturating the
throughbore;
[0058] FIGS. 4a and 4b are, respectively, a partial cutaway plan
view and a sectional view of the assembly of FIGS. 3a and 3b in its
sealing configuration; and
[0059] FIG. 4c is an end view of the valve assembly of FIG. 4a.
[0060] The valve assembly is shown generally at 10 in the figures
and comprises a substantially tubular body having an upper sub 12,
a middle sub 14 and a lower sub 16. The subs 12, 14, 16 are
connected together by means of conventional threaded pin and box
connections and are sealed by O-rings. When connected, the subs 12,
14 and 16 define a central longitudinal axis 18 and a throughbore
19 that acts as a conduit for the flow of fluids through the
tubular body. Outer ends of the top sub 12 and the bottom sub 16
have respective end box and pin connections in order to connect the
valve assembly 10 to adjacent lengths of tubing to make up the
valve assembly 10 as part of a tubing string. In this way, the
valve assembly 10 can be incorporated into a production tubing
string and run into a downhole wellbore for the recovery of
hydrocarbons from hydrocarbon reservoirs.
[0061] The middle sub 14 accommodates two flow tubes. An upper flow
tube 13 is provided adjacent the top sub 12 so that an inner
surface of the top sub 12 and an inner surface of the upper flow
tube 13 are substantially contiguous in that they share the same
internal diameter. The middle sub 14 also carries a middle flow
tube 40 that is dimensioned to be a close sliding fit thereagainst.
The middle flow tube 40 has a debris barrier 47 in the form of a
Teflon.TM. ring to restrict debris collection in an annulus between
the middle sub 14 and an outer part of the middle flow tube 40.
[0062] The longitudinal axis 18 of the throughbore 19 is offset
relative to a central longitudinal axis of the middle sub 14 as can
be seen in FIG. 1c, such that one side of each of the flow tubes
13, 40, abuts the inner surface of the middle sub 14. On the
opposing side, the flow tubes 13, 40 have a thicker sidewall to
accommodate a hydraulic sealing mechanism shown generally at 80.
The end view of FIG. 1c shows that the outer housing of the subs
12, 14, 16 extends radially outwardly relative to the throughbore
19 to a greater extent on one side of the valve assembly 10 than
the other. This creates an arcuate pocket 15 in which the hydraulic
sealing mechanism 80 is accommodated and in which a sealing member
in the form of a flapper valve 20 is housed when in the open
configuration.
[0063] The sealing mechanism 80 comprises a first piston chamber 45
that lies parallel to the longitudinal axis 18 and is in fluid
communication, via a port 46, with a hydraulic line 17 running
through a side wall of a top sub 12. The hydraulic line 17 connects
the hydraulic sealing mechanism 80 to an external supply of
hydraulic fluid. One end of a piston 42 is sealed within the
chamber 45 and the other end of the piston 42 is attached to a
protrusion 41 extending radially outwardly from one side of the
middle flow tube 40. A second piston 48 is attached to the opposing
side of the protrusion 41 so that the pistons 42, 48 and the middle
flow tube 40 are rigidly connected and moveable as one unit. The
second piston 48 is sealed in a second chamber 43 that is in fluid
communication with a hydraulic fluid line 44 that also leads to an
external supply of hydraulic fluid.
[0064] A hydraulic actuation system (not shown) produces two
controlled outputs, one of which is arranged to supply the fluid
line 17 and the other is arranged to supply the fluid line 44.
Signalling mechanisms can be used to actuate the hydraulic system.
These signalling mechanisms can include RFID tags (such as
disclosed in UK Patent No GB2420133) to initiate pre-programmed
activities, or hydraulic control lines that extend from surface.
Pressure pulses in the bore could also be used to actuate the
hydraulic system.
[0065] A third piston 22 is sealed within a third chamber 23
arranged substantially parallel to the second chamber 43. The
second piston chamber 43 has a hydraulic connecting line 26
allowing selective fluid communication between the second piston
chamber 43 and the third chamber 23, but only when the second
piston 48 uncovers the hydraulic connecting line 26. The third
piston 22 is rigidly attached to a collar 28 that carries the
flapper valve 20. As will be appreciated by those skilled in the
art, although the flapper valve 20 is intended for operation in the
circular cross-section throughbore 19, the flapper valve 20 itself
is not circular in plan view but rather is longer than it is wider.
Moreover, the flapper valve 20 in a plan view (FIG. 1a) is
substantially spade, egg- or teardrop shaped. The flapper valve 20
as shown in FIG. 2b has a central axis along its length that is
straight and parallel to the longitudinal axis of the throughbore
when the valve 20 is in the open configuration and has arcuate
sides at each side of the central axis that curve to follow a
similar radius of curvature as the lower end of the middle flow
tube 40. The flapper valve 20 is pivotally coupled to the collar 28
via a hinge 21 acting as a pivot point. Therefore, the flapper
valve 20 is moveable both axially by the movement of the piston 22
attached to the collar 28 and pivotally via the hinge 21.
[0066] The bottom sub 16 has a lower flow tube 60 positioned
adjacent thereto such that an inner surface of the bottom sub 16 is
contiguous within an inner surface of the lower flow tube 60. The
lower flow tube 60 has a shaped sealing seat 61 that is arranged to
guide the flapper valve 20 into a sealing configuration, on axial
movement of the collar 28, and allow the flapper valve 20 to seal
thereagainst. The sealing seat 61 of the lower flow tube 60 is
shaped to match and seal against a rear face of the flapper valve
20.
[0067] The outer diameter of the middle flow tube 40 is a sliding
fit within the middle sub 14 and the middle flow tube 40 is
slideable between the end of the upper flow tube 13 and the flapper
valve 20 in the throughbore 19 in a sealing configuration or the
sealing seat 61 of the lower flow tube 60 in an open configuration.
A contact edge 49 (FIG. 3a) of the middle flow tube 40 is shaped to
match and abut a leading edge of the flapper valve 20.
[0068] The flapper valve 20 is movable between an open
configuration in which the throughbore 19 of the valve assembly 10
is open (shown in FIGS. 1a-c) and a sealing configuration in which
the throughbore 19 of the valve assembly 10 is closed and fluid
passage therethrough is restricted (shown in FIGS. 4a-c).
[0069] Prior to use of the valve assembly 10, the ends of the valve
assembly 10 are connected to lengths of pipe in a tubing string
that is run downhole. The valve assembly 10 is run downhole with
the flapper valve 20 in the open configuration as shown in FIGS.
1a-c. The flapper valve 20 is accommodated within the arcuate
pocket 15 and retained in this configuration by the middle flow
tube 40 that prevents the flapper valve 20 from pivoting into the
throughbore 19. The contact face 49 of the middle flow tube 40
abuts the sealing seat 61 of the lower flow tube 60 in order that
the throughbore 19 of the valve assembly 10 remains open and fluids
can flow therethrough.
[0070] It is often required to set a packer or to pressure test the
tubing string prior to commencement of other operations. The
flapper valve 20 of the valve assembly 10 can be used to seal or
block the throughbore 19 and thereby provide a pressure retaining
barrier to conduct these operations. In such a requirement, an
operator sends a command to the hydraulic system, which supplies
fluid through the hydraulic line 44 that is in fluid communication
with the second chamber 43. As fluid collects in the second chamber
43, the second piston 48 is moved axially in a direction away from
the flapper valve 20. Since the second piston 48 is rigidly
connected to the middle flow tube 40 and the first piston 42 via
the collar 41, the middle flow tube 40 and first piston 42 are also
moved towards the top sub 12. As the first piston 42 enters the
first chamber 45, fluid is forced out of the port 46 and through
the hydraulic fluid line 17, where it is returned to the hydraulic
system. Axial movement of the middle flow tube 40 continues until
the upper end of the middle flow tube 40 abuts the lower end of the
upper flow tube 13 as shown in FIGS. 2a and 2b.
[0071] Once the second piston 48 has moved beyond the connecting
line 26 between the second chamber 43 and the third chamber 23, the
connecting line 26 is uncovered to allow fluid communication
between the second chamber 23 and the third chamber 43. As a
result, hydraulic fluid enters the third chamber 23. Fluid in the
third chamber 23 forces the third piston 22 to move towards the
bottom sub 16. Since the collar 28 and the flapper valve 20 are
connected to the third piston 22, axial movement of the third
piston 22 causes a corresponding movement of the collar 28 and
flapper valve 20. The absence of the middle flow tube 40 allows the
flapper valve 20 to pivot about the hinge 21 through 45.degree.
into the throughbore 19. The flapper valve 20 is guided into
position by the sealing seat 61 of the lower flow tube 60 as shown
in FIGS. 3a and 3b. As the flapper valve 20 travels into the
sealing configuration, the valve 20 is pushed along the sealing
seat 61 of the flow tube 60 thereby scraping debris from the seat
61. This self-cleaning action as the flapper valve 20 moves into
position over the sealing seat 61 results in an improved seal
between the valve 20 and the seat 61. In the sealing configuration,
a convex face of the flapper valve 20 makes a seal against the
sealing seat 61. This seal is made against a side of the flapper
valve 20 that is typically in the upstream position (in other words
the convex face of the flapper valve 20 faces downwards or away
from the surface of the well). The line along which the seal is
made is inclined approximately at an angle of 45.degree. relative
to the longitudinal axis 18 of the tubular.
[0072] Once the second piston 42 has reached its full extent of
travel, the second piston 42 contacts a switch (not shown)
positioned adjacent the port 46. The switch sends a command to the
hydraulic system to return the middle flow tube 40 to its original
position. The hydraulic system then supplies fluid via the
hydraulic line 12 and through the port 46 into the first chamber
45. The hydraulic fluid urges the first piston 42 towards the
flapper valve 20. This causes movement of protrusion 41 and hence
the second piston 48 and the middle flow tube 40 towards flapper
valve 20. Movement of the second piston forces fluid from the
second piston chamber 43 and into the line 44 which returns the
fluid to the hydraulic fluid system. Axial movement of the middle
flow tube 40 continues until the contact edge 49 abuts the leading
face of the flapper valve 20.
[0073] The throughbore 19 is now obturated by the presence of the
flapper valve 20. The valve seat in the form of the sealing seat,
61 and the contact edge 49 arranged to abut the flapper valve 20
ensures that the flapper valve 20 is positively held in this
position and is thus prevented from moving any further past
45.degree. or from being unintentionally retracted. The flapper
valve 20 can thus retain pressure in both directions.
[0074] The flapper valve 20 and middle flow tube 40 can be
resettable downhole. The valve assembly 10 can be programmed to
cause selective movement of the flapper valve 20 and middle flow
tube 40 to a predetermined reset configuration. Thus, the barrier
can be removed to permit two-way flow once the testing or packer
setting operations have been completed. This can be achieved by
actuation of the hydraulic system in reverse to perform the steps
of withdrawing the middle flow tube 40 and subsequently returning
the flapper valve 20 in the direction of the top sub 12, followed
by moving the middle flow tube 40 to its original position against
the sealing seat 61 of the lower flow tube 60.
[0075] In the arrangement shown in FIGS. 1a-c and 4a-c, the first
piston 42 is uncovered when the contact face 49 of the middle flow
tube 40 abuts the sealing seat 61 of the lower flow tube 60.
According to an alternative embodiment, a thin walled flow tube
could be provided to bridge this gap and substantially restrict
debris from collecting in the region of the first piston 42.
[0076] Embodiments of the present invention can seal the
throughbore 19 without requiring the flapper valve 20 to be rotated
all the way through 90.degree. and can seal the throughbore by
being rotated substantially less than 90.degree. which affords such
a flapper valve 20 with the advantage that the flapper valve 20 can
be more easily moved from the sealing configuration to the open
configuration because it is less likely to be jammed by debris
resting on it from above.
[0077] Although the above embodiment describes that a seal is
achieved by sealing the rear face of the flapper valve 20 against
the sealing seat 61, the leading face of the flapper valve 20 could
alternatively or additionally seal against the contact face 49 of
the middle flow tube 40. The seals between the flapper valve 20 and
the flow tubes 40, 60 can be carried on the sealing seat 61 or
contact edge 49 of the flow tubes 40, 60 or on the flapper valve
20. The seals can be provided by metal-to-metal contact between the
sealing seat 61 and the flapper valve 20 or rubber seals can be
provided in the region of contact between the flapper valve 20 and
the sealing seat 61.
[0078] Modifications and improvements can be incorporated without
departing from the scope of the invention. For example, the sealing
line can be planar and the sealing member can be elliptical in
shape and arranged to make a planar seal along the sealing line,
although the flapper valve 20 shown in FIGS. 1 to 4 is the
preferred shape because the arcuate flapper valve 20 is more space
efficient.
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