U.S. patent application number 11/813439 was filed with the patent office on 2009-02-05 for valve.
Invention is credited to Alan Martyn Eddison, Hazel Farquhar.
Application Number | 20090032261 11/813439 |
Document ID | / |
Family ID | 34224574 |
Filed Date | 2009-02-05 |
United States Patent
Application |
20090032261 |
Kind Code |
A1 |
Eddison; Alan Martyn ; et
al. |
February 5, 2009 |
Valve
Abstract
A downhole valve comprises a tubular body and a valve member.
The valve member is normally closed and in the closed position may
prevent or restrict passage of a working fluid through the body.
The valve member is movable to an open position, a first working
fluid pressure differential being necessary to move the valve
member from the closed position and a lower second working fluid
pressure differential being necessary to maintain the valve member
in the open position.
Inventors: |
Eddison; Alan Martyn; (York,
GB) ; Farquhar; Hazel; (Aberdeen, GB) |
Correspondence
Address: |
JEFFREY E. DALY;GRANT PRIDECO, L.P.
400 N. SAM HOUSTON PARKWAY EAST, SUITE 900
HOUSTON
TX
77060
US
|
Family ID: |
34224574 |
Appl. No.: |
11/813439 |
Filed: |
January 16, 2006 |
PCT Filed: |
January 16, 2006 |
PCT NO: |
PCT/GB06/00124 |
371 Date: |
September 4, 2008 |
Current U.S.
Class: |
166/325 |
Current CPC
Class: |
Y10T 137/0379 20150401;
E21B 34/06 20130101; Y10T 137/7783 20150401; Y10T 137/7839
20150401 |
Class at
Publication: |
166/325 |
International
Class: |
E21B 34/08 20060101
E21B034/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 14, 2005 |
GB |
0500713.3 |
Claims
1. A downhole valve comprising: a tubular body; a valve member, the
valve member being normally closed to at least restrict passage of
a working fluid through the body, and being movable to an open
position, a first working fluid pressure differential being
necessary to move the valve member from the closed position and a
lower second working fluid pressure differential being necessary to
maintain the valve member in the open position.
2. The valve of claim 1, wherein the closed valve prevents flow
through the valve.
3. The valve of claim 1, wherein the closed valve permits flow
through the valve.
4. The valve of any preceding claim, wherein the valve member is
configured to induce a fluid-flow related force tending to maintain
the valve member open.
5. The valve of any of the preceding claims, wherein the valve
member defines a restriction, and flow of the working fluid through
the valve member creates a pressure differential across at least a
portion of the valve member.
6. The valve of any of the preceding claims, wherein the body
defines a valve seat.
7. The valve of any of the preceding claims, wherein the valve is
arranged to define a first area over which fluid pressure acts on
the valve member when the valve member is in the closed
position.
8. The valve of claim 7, wherein the valve defines a larger second
area configured to induce a valve-opening fluid pressure force when
the valve member is open and fluid is flowing through the
valve.
9. The valve of claim 7 or 8, wherein the body defines a valve seat
and said valve seat defines said first area.
10. The valve of any of the preceding claims, wherein the valve
member comprises a plug portion adapted for cooperating with a
valve seat.
11. The valve of claim 10, wherein the valve is arranged such that
in the open position the plug portion is spaced from the valve
seat.
12. The valve of claim 10 or 11, wherein the plug portion is
elongate.
13. The valve of claim 10, 11 or 12, wherein the plug portion has a
tapered leading end for cooperating with the valve seat.
14. The valve of any of the preceding claims, wherein the valve
member is biased towards the closed position.
15. The valve of any of the preceding claims, wherein the valve is
adapted to be selectively retained in the open position.
16. The valve of claim 15, wherein the valve is provided in
combination with a valve-locking member adapted to selectively
retain the valve member in the open position.
17. A downhole tool comprising: a tubular body; a fluid flow
responsive member normally configured in a first configuration and
movable to a second configuration, the arrangement being such that
the member is movable from the first configuration in response to a
first fluid pressure differential across at least a part of the
member while a lower second fluid pressure differential across at
least a part of the member will maintain the member in the second
configuration.
18. The tool of claim 17, wherein the tool is configurable such
that, in the first configuration, the tool defines a first flow
restriction adapted to create a fluid pressure force over a first
area of the fluid flow responsive member, and the tool defines a
second flow restriction adapted to create a fluid pressure force
over a larger second area of said member.
19. The tool of claim 18, wherein, in the first configuration, the
area of the first flow restriction is smaller than the area of the
second flow restriction.
20. The tool of claim 18 or 19 wherein, in the second
configuration, the second flow restriction defines the minimum flow
area through the tool.
21. The tool of claim 18, 19 or 20, wherein the area of the first
flow restriction increases as the member moves towards the second
configuration.
22. The tool of any of claims 17 to 21, wherein the fluid flow
responsive member is a valve member.
23. The tool of any of claims 17 to 22, wherein the flow response
member is adapted to be operatively associated with another tool or
device.
24. A method of retaining a column of fluid in a tubular body, the
method comprising: providing a normally closed valve in a lower
portion of a tubular body; flowing fluid through the valve to
maintain the valve open; and at least reducing the fluid flow rate
to allow the valve to close and retain a column of fluid
thereabove.
25. The method of claim 24, further comprising the step of
increasing the fluid pressure above the closed valve to create a
first pressure differential across a portion of the valve to open
the valve and permit flow through the valve, and then creating a
fluid flow-related pressure differential across a larger area
portion of the valve to maintain the valve open.
26. A method of controlling flow through an elongate tubular body,
the method comprising: pumping fluid through a tubular body at a
first flow rate, the body comprising a fluid flow-responsive member
in a first configuration; and then increasing the fluid flow rate
to produce a first fluid pressure differential across a first area
to create a first actuating force, the first actuating force moving
said member towards a second configuration, and with said member in
the second configuration fluid flow at a higher second flow rate
producing a lower second fluid pressure differential across a
larger second area to create a larger second actuating force to
maintain the member in the second configuration.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a valve, and in particular but not
exclusively to a downhole valve, and most particularly to a
hydrostatic control valve.
BACKGROUND TO THE INVENTION
[0002] In the oil and gas exploration and production industry,
subsurface hydrocarbon-bearing formations are accessed by drilling
bores from surface. In a typical drilling operation a drill bit is
mounted on the lower end of a tubular string of pipe extending from
surface. Drilling fluid or "mud" is pumped down the drill pipe
string from surface and exits through jetting nozzles in the drill
bit. The drilling fluid serves a number of purposes, one being to
carry drill cuttings out of the bore, that is the drilling fluid
entrains the cuttings as the fluid flows back up to surface through
the annulus between the drill pipe and the bore wall. On surface
the cuttings are separated from the fluid, such that the drilling
fluid may be reused or recycled.
[0003] The drilling fluid may also be used as a medium to transmit
information to surface. In particular, measurement-while-drilling
(MWD) tools may be provided in a drill string, which tools include
sensors to detect, for example, bore inclination. A transducer in
the MWD tool generates a series or cycle of fluid-flow restrictions
in the bore of the tool, representative of the sensed inclination
of the bore. The restrictions create corresponding pressure pulses
in the drilling fluid above the tool. The pressure pulses are
detected and analysed on surface, to determine the measured
condition.
[0004] Problems can be encountered when drilling if lost
circulation drilling conditions are encountered; this is when a
significant volume of drilling fluid is lost into permeable
formations downhole. Thus, the volume of drilling fluid returning
to surface is less than that pumped down the bore and on occasion
drilling is performed with no returns, that is all the fluid pumped
downhole is lost.
[0005] A further problem associated with lost circulation occurs
when the drilling fluid pumps are stopped; the fluid level in the
annulus drops quickly as fluid is lost into the permeable formation
and the level of fluid within the drill pipe also drops to equalise
the fluid level (known as the U-tube effect). This can create
additional difficulties for the operation of MWD tools in such
wells as, when the drilling fluid pumps are started again, the
drill pipe must be filled with fluid before the MWD tool will start
operating and sending signals to surface. If the MWD tool starts
operating before the pipe refills the signal is likely to be lost
in the air gap. Also, MWD tools can be damaged if they operate in
the presence of a mixture of drilling fluid and gas.
SUMMARY OF THE INVENTION
[0006] According to the present invention there is provided a valve
comprising:
[0007] a tubular body;
[0008] a valve member, the valve member being normally closed to at
least restrict passage of a working fluid through the body, and
being movable to an open position to permit passage of fluid
through the body, a first working fluid pressure being necessary to
move the valve member from the closed position and a lower second
working fluid pressure being necessary to maintain the valve member
in the open position.
[0009] The valve may be adapted for use downhole, in a drilled
bore, and is preferably adapted for inclusion in a tubular string,
typically a drill string. Thus, in use, the valve may be closed and
requires the pressure of the working fluid to be raised to said
first pressure to initially open or "crack" the valve. Once the
valve is open, and the working fluid is flowing through the body,
the lower second pressure will maintain the valve open.
[0010] Embodiments of the valve may be useful for maintaining a
column of fluid in a tubular string above the valve. The valve may
be positioned in a lower portion of the string and when there is no
flow of fluid through the string the valve will close, retaining
the column of fluid above the valve. To open a valve according to a
preferred embodiment of the invention, the fluid pressure above the
valve is increased, and once the fluid is flowing through the valve
above a predetermined flow rate the pressure will reduce while the
valve remains open.
[0011] In other embodiments, the closed valve permits flow through
the valve.
[0012] Preferably, the valve member is configured to induce a
fluid-flow related force tending to maintain the valve member open.
Preferably, the valve member defines a restriction, and flow of the
working fluid through the valve member creates a pressure
differential across the valve member.
[0013] The body may define a valve seat, and the valve seat may
define a first area over which fluid pressure acts on the valve
member when the valve member is in the closed position. The valve
member may comprise a plug portion adapted for cooperating with the
valve seat. In the open position the plug portion is preferably
spaced from the valve seat, so reducing the pressure drop
experienced by fluid flowing over the valve seat and reducing
erosion. The plug portion may be elongate, and may have a tapered
leading end for cooperating with the valve seat. A collar may
define the valve seat. The body may define a larger second area
over which a valve-opening fluid pressure may act when the valve
member is in the open position, and fluid is flowing through the
valve.
[0014] The valve member may be biased towards the closed position,
preferably by a spring.
[0015] The valve may be adapted to be retained in the open
position. Preferably, the valve is provided in combination with a
valve-locking member, which may be utilised to retain the valve
member open, preferably by preventing the valve member moving to
the closed position. The member may be adapted to be pumped into
position. In other embodiments the valve member may be coupled to
the body via a cam track and the cam track may define a position in
which the valve member is prevented from closing.
[0016] According to another aspect of the present invention there
is provided a method of retaining a column of fluid in a tubular
body, the method comprising:
[0017] providing a normally closed valve in a lower portion of a
tubular body;
[0018] flowing fluid through the valve to maintain the valve open;
and
[0019] at least reducing the fluid flow rate to allow the valve to
close.
[0020] The method may further comprise the step of increasing the
fluid pressure above the closed valve to a first pressure to open
the valve and permit flow through the valve, and then creating a
fluid flow-related pressure differential across the valve to
maintain the valve open in the presence of a lower second fluid
pressure above the valve.
[0021] According to a still further aspect of the present invention
there is provided a downhole tool comprising:
[0022] a tubular body;
[0023] a fluid flow responsive member normally configured in a
first configuration and movable to a second configuration, the
arrangement being such that the member is movable from the first
configuration in response to a first fluid pressure differential
across a part of the member while a lower second fluid pressure
differential across a part of the member will maintain the member
in the second configuration.
[0024] The tool may be configured such that, in the first
configuration, the tool defines a first flow restriction adapted to
create a fluid pressure force over a first area of the member, and
the tool defines a second flow restriction adapted to create a
fluid pressure force over a larger second area of the member. In
the first configuration the first flow restriction may define the
minimum flow area through the tool. In the second configuration the
second flow restriction may define the minimum flow area through
the tool. This may be effected by increasing the area of the first
flow restriction as the member moves towards the second
configuration. This may be achieved by movement of the member
relative to the body, or by relative movement of parts of the
member.
[0025] The fluid flow responsive member may be a valve member. In
the first configuration the valve member may close or restrict
fluid flow through the tool.
[0026] The flow response member may be operatively associated with
another tool or device, such as a bypass tool. Movement of the
member may activate, actuate or otherwise reconfigure the other
tool or device.
[0027] Other preferred and alternative features of this aspect of
the invention may coincide with the preferred and alternative
features of the first-described aspect, wherein the fluid flow
responsive member may include or incorporate the features of the
valve member.
[0028] According to a still further aspect of the present invention
there is provided a method of controlling flow through an elongate
tubular body, the method comprising:
[0029] pumping fluid through a tubular body at a first flow rate,
the body comprising a fluid flow responsive member in a first
configuration; and then
[0030] increasing the fluid flow rate to produce a first fluid
pressure differential across a first area to create a first
actuating force, the first actuating force moving said member
towards a second configuration, and with said member in the second
configuration fluid flow at a higher second flow rate producing a
lower second fluid pressure differential across a larger second
area to create a larger second actuating force to maintain the
member in the second configuration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] These and other aspects of the present invention will now be
described, by way of example, with reference to the accompanying
drawings, in which:
[0032] FIG. 1 is a sectional view of a hydrostatic control valve in
accordance with a preferred embodiment of the present invention,
the valve being illustrated in the closed configuration;
[0033] FIG. 2 corresponds to FIG. 1, but shows the valve in the
open configuration; and
[0034] FIG. 3 corresponds to FIG. 1, and shows the valve in being
held in the open configuration.
DETAILED DESCRIPTION OF THE DRAWINGS
[0035] Reference is first made to FIG. 1 of the drawings which
illustrates a valve, in the form of a downhole hydrostatic control
valve 10, in accordance with a preferred embodiment of the present
invention. FIG. 1 illustrates the valve in the closed
configuration. The valve 10 comprises a tubular body 12 having ends
adapted for coupling to drill pipe sections such that the valve 10
may be incorporated in a string of drill pipe. As will be
described, in use the valve 10 is located in the lower end of a
drill string and is designed to maintain the drill pipe full of
fluid when the drilling fluid pumps are stopped but without an
unacceptable increase in circulating pressure at higher flow
rates.
[0036] The body 12 contains a fixed valve seat 16 which defines a
central through bore 18 of area A1 (FIG. 2). The valve seat 16
cooperates with a valve plug 20 forming part of a valve member 22
which is axially movable within the body 12 to control the opening
and closing of the valve 10. The valve member 22 itself comprises a
tubular body 24 to which the valve plug 20 is mounted by spaced
arms 26, which allow for the free flow of fluid past the plug 20.
The body 24 defines a nozzle 28, followed by a tubular sleeve 30
around which is mounted a coil spring 32 which tends to bias the
valve member 22 towards the closed position. The valve member body
24 carries O-ring seals 34 which provide a sliding seal with the
inner wall of the body 12. Accordingly, any differential fluid
pressure created by flow through the nozzle 28 acts across the
cross-sectional area of the valve body 24, area A2 (FIG. 2), which
area is significantly larger that area A1.
[0037] The collar 36 supporting the lower end of the spring 32
forms the lower end of a spring chamber and defines fluid ports 38.
To provide damping for the valve member the ports 38 may be
relatively small, to restrict the flow of fluid into and from the
spring chamber.
[0038] When there is no flow and the valve 10 is closed (FIG. 1)
the valve plug 20 is held against the valve seat 16 by the spring
32. When flow is started the static fluid pressure required to
begin opening the valve is the force from the spring 32 divided by
the area A1, which pressure is supplied from the surface drilling
fluid pumps. However, when flow is established and increased to
higher rates there is also a pressure differential produced across
the nozzle 28. This pressure acts on area A2 which, as noted above,
is significantly larger than area A1, and at a threshold flow rate
the force produced by the pressure differential across the nozzle
28 acting on area A2 will exceed the force produced by the fluid
pressure differential across the valve plug 20 acting on area A1.
At this point the valve closing spring 32 will be further
compressed and the valve plug 20 is moved away from the valve seat
16. This will tend to reduce the pressure drop and fluid velocity
between the valve plug 20 and the valve seat 14, thus preventing
fluid erosion damage in this area and reducing the pressure
required to keep the valve open. The pressure losses induced by the
valve are also reduced, particularly as the flow rate of fluid
through the valve 10 is increased.
[0039] When the flow rate is subsequently reduced below the
threshold level the valve plug 20 will again be forced towards the
valve seat 16 and the pressure drop across the tool will increase.
When the flow is stopped the valve plug 20 will contact the valve
seat 16 preventing any further flow and maintaining the drill pipe
above the valve 10 full of drilling fluid.
[0040] Typical values for a valve in accordance with this
embodiment of the invention are as follows:
Tool size (o.d.): 8'' Valve opening pressure: 1,500 psi Threshold
flow rate: 800 gpm Pressure drop across valve @ 1,200 gpm: 550
psi
[0041] Thus it is apparent that a relatively high fluid pressure
(1,500 psi) is required to open the valve 10, but that once fluid
is flowing through the valve 10 at a predetermined rate, in this
case 800 gpm, the valve 10 will remain open even if the upstream
pressure of the fluid falls below the opening pressure; the flow of
fluid through the nozzle 28 creates a pressure differential which
acts across a relatively large area A2 and serves to retain the
valve open. As is apparent from the above-noted figures, the
relatively large area A2 allows the pressure drop across the valve
10 to be kept to a low level at operating flow rates.
[0042] A potential disadvantage of such a hydraulic control valve
10 is that when pulling out of hole the valve 10 will be closed and
the drill pipe will remain full of drilling fluid. This is
inconvenient because when each stand of drill pipe is disconnected
at surface a significant amount of drilling fluid is released onto
the rig floor. This fluid normally must be contained and returned
to the drilling fluid system, which can be time consuming and
costly. To avoid this difficulty, the valve may be maintained in
the open position, and one example of how this could be achieved is
illustrated in FIG. 3 of the drawings. Prior to pulling out, a
spring collet dart 40 is pumped down from surface, the spring
fingers 42 of the dart being deformable such that the fingers 42
can squeeze through the valve seat 16. Once through the valve seat
16, the fingers 42 spring open and the dart 40 rests on the end of
the valve plug 20. When the flow is stopped it is not possible for
the collet to pass back through the valve seat 16 because the valve
plug 20 traps the fingers 42. This prevents the valve 10 from
sealing and allows drilling fluid to drain through the valve 10,
such that the drill pipe is empty when pulling out of hole.
[0043] In use, the valve 10 may be located in a drill string
adjacent an MWD tool. In normal operation, the valve 10 will be
kept open by the flow of drilling fluid through the string. If lost
circulation conditions are encountered, and the drilling fluid
pumps are stopped, the flow of drilling fluid through the valve 10
will cease and the valve 10 will close. Thus, the column of
drilling fluid in the drill string above the valve 10 is retained,
even if the fluid level in the annulus drops, as fluid is lost into
the permeable formation. When the pumps are restarted, the pressure
in the drill string above the valve rises until reaching a level
sufficient to open the valve 10. The fluid then flows through the
valve 10 and soon reaches the level required to maintain the valve
10 open. During this period, the MWD tool will have remained filled
with fluid, and there will be a continuous column of fluid above
the MWD tool, ensuring proper operation of the tool and providing
for transmission of signals from the MWD tool to surface.
[0044] The valve 10 as described above may also be utilised in
other applications, or modified forms of the valve may be utilised,
as described below.
[0045] In the above-described application the valve 10 prevents
flow when in the closed configuration. However, valves or tools in
accordance with other aspects of the invention may be configured to
permit flow in the first or "closed" configuration. With reference
to the illustrated embodiment, this could be achieved by, for
example, providing ports extending through the valve seat 16, or by
changing the form of the plug 20 such that at least the upper end
of the plug 20 is of smaller diameter than the seat 16 and an open
annulus remains between the plug 20 and seat 16. In this
configuration, fluid may be pumped through the closed valve 10 and
thus circulated through a pipe string. However, if it is desired to
circulate or pump fluid at a relatively high rate, with lower
pressure losses, this may be achieved by opening the valve 10. Of
course this may be accomplished quickly and easily merely by
increasing the pump rate.
[0046] In other embodiments the valve member 22 may also be coupled
to other tools or devices and the movement of the valve member 22
utilised to activate, actuate or reconfigure another tool or
device. In one embodiment the movement of the valve member 22 may
open and close a bypass port, as described below, and may be
useful, for example, in fracture acidising operations.
[0047] For an acidising application such as this the valve 10 may
be configured to permit flow when the valve is in the first
configuration and may be mounted to coiled tubing above an
agitator, such as applicant's AG-itator tool. The valve member 22
is coupled to a bypass tool provided between the valve 10 and the
agitator, the bypass tool being normally closed. The bypass tool is
also of the form which, when the side ports are open, the axial
passage through the tool providing fluid access to the agitator is
closed.
[0048] As the coiled tubing is run into the bore, fluid is
circulated through the tubing to actuate the agitator, the
vibration produced by the agitator assisting in advancing the
tubing through the bore. The fluid flow rate and fluid pressure
necessary to operate the agitator is relatively low and during the
running-in phase of the operation the valve 10 remains in the
"closed" configuration, as do the side ports of the bypass
tool.
[0049] When the bypass tool is located adjacent the formation to be
fractured, acid is pumped from surface at a high pressure and flow
rate through the coiled tubing. There will be an initial resistance
to the higher flow rate from the initially closed valve 10.
However, as the flow rate through the valve 10 increases the
pressure differential induced by the nozzle 28 and acting across
the whole area of the valve body 24 will increase and the valve 10
will open. Thus, as the plug 20 is moved away from the seat 16 the
pressure drop across the valve 10 will decrease as the flow rate
increases. Simultaneously, the side ports of the bypass tool will
open, and the further flow of fluid into and through the agitator
will be prevented.
[0050] The acid being pumped down through the coiled tubing will
thus pass through the open valve 10 and then pass through the side
ports of the bypass tool into the formation. The actuation of the
bypass tool also protects the agitator from the potentially
damaging effects of the acid, and from the elevated flow which
could create a pressure differential across the agitator sufficient
to damage the agitator.
[0051] It will be apparent to those of skill in the art that the
above-described embodiments are merely exemplary of the present
invention, and that various modifications and improvements may be
made thereto, without departing from the scope of the invention.
For example, a number of alternative mechanisms could be used to
lock the valve 10 open for pulling out of hole. Furthermore, to
damp movement of the valve member 22 and to prevent or limit
vibration when the valve is opening, the valve may include a
dashpot-type damping mechanism.
* * * * *