U.S. patent application number 10/748515 was filed with the patent office on 2004-09-09 for electric downhole safety valve.
Invention is credited to Loth, William D., Waithman, James C. P..
Application Number | 20040173362 10/748515 |
Document ID | / |
Family ID | 32930394 |
Filed Date | 2004-09-09 |
United States Patent
Application |
20040173362 |
Kind Code |
A1 |
Waithman, James C. P. ; et
al. |
September 9, 2004 |
Electric downhole safety valve
Abstract
An electrically actuated fail-safe valve for controlling fluid
flow in deepwater drilling operations comprises a body having a
bore therethrough, a closure element mounted in the bore and
actuable between a closed position and an open position, a flow
tube slidably mounted in the bore, the tube being actuable between
a first position in which it does not interfere with the normal
bias of the closure and a second position in which it opposes the
normal bias of the closure, and a drive mechanism causing the tube
to advance from its first to its second position. The drive
mechanism comprises a gear drive, a rotating sleeve including a
helical groove, and a follower pin on the flow tube and received in
the helical groove. Power supplied to the drive causes the sleeve
to rotate, bearing on the follower pin and advancing the flow tube
to its second position.
Inventors: |
Waithman, James C. P.;
(Houston, TX) ; Loth, William D.; (Lower
Kingswood, GB) |
Correspondence
Address: |
CONLEY ROSE, P.C.
P. O. BOX 3267
HOUSTON
TX
77253-3267
US
|
Family ID: |
32930394 |
Appl. No.: |
10/748515 |
Filed: |
December 30, 2003 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60437070 |
Dec 30, 2002 |
|
|
|
Current U.S.
Class: |
166/386 ;
166/66.7 |
Current CPC
Class: |
E21B 34/066
20130101 |
Class at
Publication: |
166/386 ;
166/066.7 |
International
Class: |
E21B 033/12 |
Claims
What is claimed is:
1. An electrically actuated fail-safe valve for controlling fluid
flow in a deepwater drilling operation, comprising: a body having a
bore therethrough; a closure element mounted in the bore and
actuable between a closed position in which said bore is relatively
obstructed and an open position in which said bore is relatively
open, said closure element being biased to one of said closed and
open positions; a flow tube slidably mounted in said bore, said
flow tube being actuable between a first position in which said
flow tube does not interfere with the normal bias of said closure
element and a second position in which said flow tube opposes the
normal bias of said closure element so as to maintain said closure
element in the other of said closed and open positions; an
electrically powered drive mechanism mounted in said body and
engaging said flow tube so as to advance said flow tube from said
first position to said second position.
2. The valve according to claim 1 wherein said closure element is
biased into said closed position and said drive mechanism advances
said flow tube such that said flow tube actuates said closure
element to said open position.
3. The valve according to claim 1, further including a plurality of
powered drive mechanisms, said drive mechanisms including one-way
drive clutches and allowing nonfunctioning drive mechanisms to be
mechanically decoupled.
4. The valve according to claim 1 wherein the drive mechanism
comprises: a gear drive, a rotating sleeve mounted in said body,
said rotating sleeve including a helical groove, and a follower pin
mounted on said flow tube and received in said helical groove; such
that electrical power supplied to said gear drive causes said
rotating sleeve to rotate, which in turn bears on said follower pin
and advances said flow tube to said second position.
5. The valve according to claim 4 wherein the helical groove
includes a straight portion substantially parallel to the
longitudinal axis of said bore.
6. The valve according to claim 4 wherein the helical groove
includes a transverse portion substantially perpendicular to the
longitudinal axis of said bore.
7. The valve according to claim 4, further including means for
preventing longitudinal rotation of said flow tube.
8. The valve according to claim 1, further including an
electrically actuable retaining mechanism mounted in said body and
actuable between an engaged position in which said retaining
mechanism engages said flow tube and prevents axial movement of
said flow tube relative to said body and a disengaged position in
which said retaining mechanism allows axial movement of said flow
tube relative to said body.
8. The valve according to claim 1, further including a biasing
means urging said flow tube into said first position.
9. An electrically actuated fail-safe valve for controlling fluid
flow in a deepwater drilling operation, comprising: a body having a
bore therethrough; a closure element mounted in the bore and
actuable between a closed position in which said bore is relatively
obstructed and an open position in which said bore is relatively
open, said closure element being biased to said closed position; a
flow tube slidably mounted in said bore, said flow tube being
actuable between a first position in which said flow tube does not
interfere with the normal bias of said closure element and a second
position in which said flow tube opposes the normal bias of said
closure element so as to maintain said closure element in the other
of said closed and open positions; an electrically powered drive
mechanism mounted in said body and engaging said flow tube so as to
advance said flow tube from said first position to said second
position such that said flow tube actuates said closure element to
said open position, said drive mechanism comprising: a gear drive,
a rotating sleeve mounted in said body, said rotating sleeve
including a helical groove, and a follower pin mounted on said flow
tube and received in said helical groove; wherein power supplied to
said gear drive causes said rotating sleeve to rotate, which in
turn bears on said follower pin and advances said flow tube to said
second position.
10. The valve according to claim 1, further including a plurality
of powered drive mechanisms, said drive mechanisms including
one-way drive clutches and allowing nonfunctioning drive mechanisms
to be mechanically decoupled.
11. The valve according to claim 9 wherein the helical groove
includes a straight portion substantially parallel to the
longitudinal axis of said bore.
12. The valve according to claim 9 wherein the helical groove
includes a transverse portion substantially perpendicular to the
longitudinal axis of said bore.
13. The valve according to claim 9, further including means for
preventing longitudinal rotation of said flow tube.
14. The valve according to claim 9, further including an
electrically actuable retaining mechanism mounted in said body and
actuable between an engaged position in which said retaining
mechanism engages said flow tube and prevents axial movement of
said flow tube relative to said body and a disengaged position in
which said retaining mechanism allows axial movement of said flow
tube relative to said body.
15. The valve according to claim 9, further including a biasing
means for urging said flow tube into said first position.
16. A method for controlling fluid flow in a deepwater drilling
operation, comprising: a) providing a tool having a bore
therethrough, the tool including a closure element actuable between
a closed position in which the closure element closes said bore and
an open position in which the closure element allows fluid flow
through the bore, the closure element being biased normally closed,
the tool further including a flow tube slidably mounted in said
bore, the flow tube being actuable between a first position in
which the flow tube does not prevent the closure element from being
in its normally biased position and a second position in which the
flow tube opposes the normal bias of the closure element so as to
actuate the closure element to the open position; b) selectively
actuating said flow tube so as to actuate the closure element to
the open position.
17. The method according to claim 16 wherein the tool further
includes a rotating sleeve and a follower pin extending from the
flow tube and engaging a helical groove in said rotating sleeve and
wherein the actuating step comprises rotating the sleeve such that
engagement of the follower pin in the helical groove advances the
flow tube from the first position to the second position.
18. The method according to claim 16 wherein the tool further
comprises a releasable locking mechanism and said helical groove
includes a longitudinal straight portion such that when the
follower pin lies in the longitudinal straight portion of the
groove and the locking mechanism is released, the biasing of the
closure element causes the flow tube to move to the first
position.
19. The method according to claim 18 wherein the locking mechanism
is electrically actuated.
20. The method according to claim 16 wherein the flow tube is
actuated using electrical power.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S.
Provisional Application Serial No. 60/437,070, filed Dec. 30, 2002
and entitled "Electric Downhole Safety Valve," which is
incorporated herein by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable.
FIELD OF THE INVENTION
[0003] The present invention relates generally to downhole safety
valves and more particularly to a downhole safety valve that is
electrically operated.
BACKGROUND OF THE INVENTION
[0004] The invention relates to a surface controlled subsurface
safety valve (SCSSV) for a sub-terranean well and, more
particularly, to a safety valve utilizing an electrical actuation
mechanism controlled from the surface or by a downhole intelligent
controller.
[0005] Oil and gas wells typically employ at least one safety valve
that can be actuated to stop or control the flow of fluid through a
pipe. These valves are normally positioned downhole to close the
bore of the tubing string extending from one or more production
zones to the well surface. Safety valves of this type include a
spring that biases the valve to a fail-safe mode, such that an
interruption in the force acting to keep the valve open will cause
the valve to close.
[0006] Conventional downhole safety valves are hydraulically
operated. As oil and gas reserves are developed in deepwater,
however, the column of fluid needed for hydraulic actuation becomes
impractically long. Specifically, the hydrostatic head developed in
a conventional hydraulically controlled valve results in high
operating pressures and requires an unworkably large failsafe
spring.
[0007] Because of the problems with hydraulically controlled safety
valves, electrically operated safety valves are an attractive
alternative. In addition, intelligent completion systems are being
developed that are equipped with a variety of electrically driven
flow control devices. Hence, it is currently desirable to provide
an all-electric control system and remove the requirement for any
hydraulic supply. Electrically controlled downhole safety valves
have been developed, but they generally require high power
consumption and/or unfavorably large geometry, and are vulnerable
to problems with electrical connections to the surface.
[0008] Hence, it remains desirable to provide an electrically
operated downhole safety valve that can operate effectively and
reliably at deep setting depths, using available power
downhole.
SUMMARY OF THE INVENTION
[0009] The present invention provides an electrically operated
downhole safety valve that can operate effectively and reliably
using available power downhole. In a preferred embodiment, the
present system fits into a casing no larger than would be required
for a comparable hydraulic unit.
[0010] The various characteristics described above, as well as
other features, will be readily apparent to those skilled in the
art upon reading the following detailed description of the
preferred embodiments of the invention, and by referring to the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] For a more detailed description of the preferred embodiments
of the present invention, reference will now be made to the
accompanying drawings, wherein:
[0012] FIG. 1 is a schematic cross-section of a device constructed
in accordance with a preferred embodiment of the present invention,
showing the valve in a closed position;
[0013] FIG. 2 is a schematic cross-section of the device of FIG. 1,
showing the valve in a open position;
[0014] FIG. 3 is a cross-section taken along lines 3-3 of FIG. 2;
and
[0015] FIGS. 4 and 5 are cross-sections taken along lines 4-4 and
5-5 of FIG. 2, showing the restraining mechanism in its
de-energized and energized states, respectively.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] Referring initially to FIG. 1, a device constructed in
accordance with a preferred embodiment of the present invention
comprises a generally cylindrical body 10 having a central bore 12
therethrough and a concentric flow tube 50 slidably mounted in bore
12. Body 10 includes a first end 13 and a second end 14, and
preferably includes female threads 15 at each end. In addition,
bore 12 includes a valve receptacle 16, a spring receptacle 26, an
eccentric gearbox receptacle 36, and a guide groove 46, all
described in detail below.
[0017] Flow tube 50 comprises a cylindrical tube having a first end
53 and a second end 54. The outer surface of flow tube 50 includes
a first, annular extension 56 spaced a first distance from first
end 53 and a second, non-annular extension 58 spaced a further
distance from first end 53. In addition, the outer surface of flow
tube 50 includes an outwardly extending follower pin 59 between
annular extension 56 and non-annular extension 58.
[0018] Referring still to FIG. 2 and in particular to bore 12 in
body 10, valve receptacle 16 comprises a first increased diameter
portion in bore 12. Valve receptacle 16 is bounded by a lower,
frustoconical shoulder 17 and an upper, annular shoulder 18. The
inside diameter of valve receptacle 16 is greater than the outer
diameter of flow tube 50, creating a chamber 19 therebetween. A
closure element 20 is housed in chamber 19, along with a spring 22.
Closure element 20 is pivotally mounted such that it can pivot
about a transverse axis between a closed position, shown in FIG. 1,
in which it bears on annular shoulder 18, and an open position,
shown in FIG. 2. In its closed position, closure element 20
preferably substantially obstructs the flow of fluid through bore
12 and in its open position it does not. It will be understood that
the closed and open positions need not be completely closed or
completely open. In other words, the closed and open positions may
be merely relative; namely, the closed position being one in which
less fluid is allowed to pass than is allowed in the open position.
Spring 22 is preferably mounted between closure element 20 and body
10 such that it bears on closure element and urges it into its
closed position. Sprint 22 is shown as a coil spring, but it will
be understood that spring 22 can comprise any suitable biasing
member.
[0019] Spring receptacle 26 comprises a second increased diameter
portion in bore 12 spaced farther from end 13 than valve receptacle
16. Spring receptacle 26 is bounded by a lower annular shoulder 27
and an upper annular shoulder 28. The inner diameter of spring
receptacle 26 is greater than the outer diameter of flow tube 50,
creating an annular chamber 29 therebetween. A coil spring 30 is
preferably disposed in chamber 29 between lower annular shoulder 27
of spring receptacle 26 and annular extension 56 of flow tube 50.
Spring 30 is preferably sized such that it is compressed and urges
flow tube 50 away from first end 13 even when annular extension 56
bears on upper annular shoulder 28.
[0020] Eccentric gearbox receptacle 36 comprises a third enlarged
portion in bore 12 and is spaced farther from end 13 than spring
receptacle 26. Eccentric gearbox receptacle 36 comprises a lower
portion 37 and an upper portion 38. Lower portion 37 houses at
least one and preferably a plurality of drive motors 40, gearboxes
42, and gears 44. Upper portion 38 houses a rotating sleeve 46.
Rotating sleeve 46 includes a looped groove 48, which includes a
helical portion 47, a short, transverse portion 51, and a straight
portion 49. Looped groove 48 receives follower pin 59 on flow tube
50. When closure element 20 is in the closed position shown in FIG.
1, follower pin 59 is disposed at a junction between straight
portion 49 and helical portion 47.
[0021] Drive motors 40, gearboxes 42, gears 44 and rotating sleeve
46 are preferably operably connected such that power supplied to
drive motors 40 causes motors 40 drive gearboxes 42, which in turn
drive gears 44, which in turn cause rotating sleeve 46 to rotate
about the axis of body 10 and flow tube 50. FIG. 3 is a
cross-sectional view along the axis of the device with the rotating
sleeve 46 removed so as to show the plurality of gearboxes 42 and
gears 44. FIG. 3 also illustrates the extension of follower pin 59
from the outer surface of flow tube 50.
[0022] Guide groove 46 extends longitudinally along a portion of
bore 12 and receives non-annular extension 58 of flow tube 50.
Referring briefly to FIGS. 4 and 5, guide groove 46 preferably is
wide enough to include at least a pair of retaining members 68.
Retaining members 68 are actuable between an open position, shown
in FIG. 4, and a closed position, shown in FIG. 5. In their closed
position, retaining members 68 engage extension 58 so as to prevent
flow tube 50 from moving relative to body 10.
[0023] Retaining members 68 and drive motors 40 receive electrical
power from electrical leads 7, 9, respectively. Conductors 7, 9
preferably enter body 10 through electrical penetrator 8.
Conductors 7, 9 electrically connect to a local control unit 100,
which is in turn electrically connected to a remote control unit
102.
[0024] A plurality of seals 70 are preferably provided between body
10 and flow tube 50 so as to isolate guide groove 46, eccentric
gearbox receptacle 36, and spring receptacle 26 and prevent the
ingress of fluid thereinto.
[0025] Operation
[0026] When it is desired to open bore 12 and allow fluid flow
therethrough, a preferred first step is to equalize pressure on
both sides of closure element 20. With pressure equalized, power is
supplied to motors 40 via conductors 9. Motors 40 drive gearboxes
42, which in turn advance gears 44, causing sleeve 46 to rotate
such that follower pin 59 enters the helical portion 47 of loop 48.
As sleeve 46 rotates, helical groove 47 bears on pin 59, urging
flow tube 50 toward first end 13 of body 10. Because flow tube 50
is prevented from rotating by engagement of extension 58 with guide
groove 46, the rotation of sleeve 46 causes flow tube 50 to advance
longitudinally through body 10. As flow tube 50 advances relative
to body 10 in response to the force applied by rotating sleeve 46,
annular extension 56 compresses spring 30 and first end 53 bears on
closure element 20, forcing it open. If pressure is not equalized
before the opening sequence, more power may be required to open the
valve.
[0027] When the opening process is complete, the tool is in the
position shown in FIG. 2. Specifically, end 53 of flow tube 50
rests on frustoconical shoulder 17 and closure element 20 is
contained between body 10 and flow tube 50. Bore 12 is open along
the length of the tool, spring 30 is compressed, and follower pin
59 rests at the juncture of helical portion 47 and straight portion
49, as shown in phantom. At this point, power is supplied to
retaining members 68, causing them to come together and engage
extension 58 of flow tube 50 so as to prevent it from moving
axially within body 10. Rotation of sleeve 46 is then preferably
continued, without further advancing flow tube 50, as follower pin
59 traverses transverse portion 51 of loop 48, until follower pin
59 rests at the juncture of transverse portion 51 and straight
portion 49, as shown in FIG. 2.
[0028] Because the present invention is normally closed, it is a
fail-safe valve. Once the device has attained the open state shown
in FIG. 2, flow can continue through it until either the device is
closed deliberately, the power supplied to retaining members 68 is
interrupted, or retaining members 68 fail. When any of these events
occurs, retaining members 68 cease to hold extension 58 and thus
cease to prevent flow tube 50 from moving axially. This allows
spring 30 to drive flow tube 50 away from first end 13. As flow
tube 50 advances toward second end 14, follower pin 59 traverses
straight portion 49 of loop 48. Flow tube 50 is sized such that
when annular extension 56 bears on upper annular shoulder 28, its
first end 53 clears upper annular shoulder 18, allowing closure
element 20 to fully close bore 12.
[0029] Because the device preferably includes a plurality of motors
40, a plurality of gearboxes 42, and a plurality of gears 44, it is
multiply redundant, ensuring that it remains operable even in the
event that one or more of its components fail. In addition, the
gear train may be fitted with multiple slip clutches that will
allow the device to operate even if one or more of the redundant
drive motors fail.
[0030] Retaining members 68 can be any electrically actuable device
and are shown as a pair of electrically actuated dogs. In a
preferred embodiment, retaining members 68 each comprise at least
one flux carrier in conjunction with at least one coil. The coils
are connected to conductors 7. When power is supplied to the coils,
they induce flux in the flux carriers, which in turn advance toward
extension 58 and ultimately engage it. By using electrical
actuation and electrical power, the present device avoids the need
for hydraulic systems.
[0031] Flow tube 50 preferably includes a static sealing member at
its first end 53, which forms a seal with frustoconical shoulder 17
when the device is open. Flow tube 50 can be rotated to remove
deposits that would otherwise impede travel of the tube. In some
embodiments, flow tube 50 includes a toothed cutting edge to
facilitate removal of deposits.
[0032] In still another alternative embodiment, the relative
positions of the drive mechanism and spring 30 may be reversed,
such that the flow tube is pulled into the open position against
the spring force. In this embodiment it is still preferred that the
device be normally closed, so that it can function as a fail-safe
device. Nonetheless, it is contemplated that in other embodiments,
the configuration may be modified such that the device is normally
open. In these embodiments, the relative positions of spring 30 and
the drive mechanism may again be such that the drive mechanism
either pulls or pushes the flow tube into the closed position.
[0033] While certain preferred embodiments of the present invention
has been shown and described, it will be understood that a variety
of modifications could be made thereto without departing from the
scope of the present invention. For example, the guiding and
retaining functions performed by extension 58 could be performed by
separate elements. Closure element 20, shown above as a single
component could comprise multiple components and/or could operate
in various other ways. For example, closure element 20 could
comprise a shutter-type closure, a ball valve, a stopcock-type
closure, or any other suitable closure device. Likewise, the
spring- loaded pivoting mechanism described above could comprise
any suitable biasing means such as are known in the art.
[0034] The drive mechanism described above as formed by the
combination of gears, rotating sleeve, and follower pin could be
replaced with a drive mechanism comprising solely gears, with the
drive motors rotating a set of gears to either directly or
indirectly advance the flow tube. For example, the flow tube could
include gear teeth on a portion of its outer surface. Similarly, a
plurality of powered drive mechanisms can be included and can
include one-way drive clutches. The drive mechanism(s) can be
configured so as to allow nonfunctioning drive mechanisms to be
mechanically decoupled.
[0035] Coil spring 30 can be replaced with a biasing means that is
better suited to operate in tension, rather than in compression, if
desired. Flow tube 50 can be replaced with a non-tubular element,
although a tubular element is preferred because it is mechanically
robust and protects the various components of the device from
contact with the fluid. Similarly, retaining members 68 could be
replaced with a single member, or multiple members, mounted inline
with extension 58, which when face to face with extension 58 can
retain extension 58 when energized.
[0036] The embodiments described herein are exemplary only and are
not limiting. One skilled in the art will understand that the
mechanisms described herein could each be replaced with alternative
mechanisms, so long as the invention is within the scope of the
claims that follow. Accordingly, the scope of protection is not
limited to the embodiments described herein, but is only limited by
the claims which follow, the scope of which shall include all
equivalents of the subject matter of the claims. Also, in the
claims that follow, the sequential recitation of steps is not
intended to require that the steps be performed in the order
recited, or that any given step be completed before another step is
begun.
* * * * *