U.S. patent number 3,882,935 [Application Number 05/427,795] was granted by the patent office on 1975-05-13 for subsurface safety valve with auxiliary control fluid passage openable in response to an increase in control fluid pressure.
This patent grant is currently assigned to Otis Engineering Corporation. Invention is credited to Michael B. Calhoun.
United States Patent |
3,882,935 |
Calhoun |
May 13, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
Subsurface safety valve with auxiliary control fluid passage
openable in response to an increase in control fluid pressure
Abstract
A valve for installation in a flow conductor for controlling
flow of fluids through the conductor, which may be controlled from
a remote point and which may act automatically as a safety valve,
including means for positively propping the valve in an open
position or in a position intermediate open and closed positions
for taking the valve out of operation permanently or for flowing
the well without affecting operation of the valve, and further
including means for locating and operating a supplemental flow
control valve at such point in the flow conductor. Also includes
means normally closing a lateral control fluid passage in the
housing of the valve which is openable by increased control fluid
pressure for thereafter conducting control fluid to and controlling
a supplemental flow control which may be disposed through the
valve.
Inventors: |
Calhoun; Michael B.
(Carrollton, TX) |
Assignee: |
Otis Engineering Corporation
(Dallas, TX)
|
Family
ID: |
23696319 |
Appl.
No.: |
05/427,795 |
Filed: |
December 26, 1973 |
Current U.S.
Class: |
166/322; 251/58;
166/323 |
Current CPC
Class: |
E21B
34/106 (20130101) |
Current International
Class: |
E21B
34/00 (20060101); E21B 34/10 (20060101); E21b
043/12 () |
Field of
Search: |
;166/224A,224,226,72
;251/58,62 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Leppink; James A.
Attorney, Agent or Firm: Carroll; Albert W.
Claims
What is claimed and desired to be secured by letters patent is:
1. A well flow conductor valve including: a housing having means
for connecting it in flow communication with a well flow conductor;
valve means disposed in the housing and movable therein between
open and closed positions for controlling flow through the housing;
operating means in said housing movable longitudinally thereof for
actuating said valve to move the same between the open and closed
positions; locking means in the housing initially in an inoperative
position spaced from said operating means and movable to a position
engaging said valve operating means to positively lock said valve
operating means in position holding said valve in open position;
fluid pressure responsive means on said operating means; means for
conducting control fluid pressure to said valve housing for acting
on said fluid pressure responsive means to control movement of said
operating means in response to such control fluid pressure; means
at the surface for controlling fluid pressure conducted through
said control fluid conductor means to the valve in response to
predetermined conditions; and means providing a control fluid
passage into the interior of the valve housing responsive to an
increased control fluid pressure after said locking means has been
moved to position locking said valve means in open position, said
increased control fluid pressure being substantially higher than
the control fluid pressure required to operate said operating
means.
2. The device of claim 1 in combination with a supplementary safety
valve disposed therein and actuated by control fluid pressure
conducted to the same through said control fluid passage.
3. The device of claim 1 wherein said means for providing said
control fluid passage into the interior of said valve includes: a
port in the wall of said housing; plug means plugging said port;
and means releasably retaining said plug means against displacement
from said port means and releasable in response to said increased
control fluid pressure.
4. The device of claim 5 wherein said plug in said port has its
inner and outer sides subjected to control fluid pressure when said
sleeve is in said inoperative position.
5. The device of claim 3 wherein said plug in said port has its
inner and outer ends subjected to well fluid pressure when said
sleeve is in said inoperative position.
6. The device of claim 3 wherein said plug means includes a plug
disposed in said port and seal means engaged between said plug and
the wall of said port for preventing flow of control fluid through
said port when said plug is disposed therein, and said releasable
means is a shear pin disposed in an aperture in said plug and
having at least one of its ends engaged with said housing, said
shear pin being shearable responsive to said increased control
fluid pressure to displace said plug from said port, whereby said
control fluid passage into the interior of said valve housing is
opened upon a substantial increase in control fluid pressure.
7. The device of claim 3 wherein said plug means is a disk
sealingly disposed in said port and being displaceable from such
sealing position by said increased control fluid pressure.
8. A well flow conductor valve comprising: a housing having means
connecting it in flow communication with a well flow conductor;
valve means disposed in the housing and movable therein between
open and closed positions for controlling flow through the housing;
operating means in said housing movable longitudinally thereof for
actuating said valve to move the same between open and closed
positions; fluid pressure responsive means on said operating means;
means for conducting control fluid pressure to said valve housing
for acting on said fluid pressure responsive means to control
movement of said operating means in response to such control fluid
pressure; means at the surface for controlling fluid pressure
conducted through said control fluid conductor means to the valve
in response to predetermined conditions; and means providing a
control fluid passage into the interior of the valve housing
responsive to an increased control fluid pressure substantially
higher than the control fluid pressure required to operate said
operating means.
9. The device of claim 8 wherein said means for providing said
control fluid passage into the interior of said valve is a port in
the wall of said housing and includes plug means plugging said port
and means releasably retaining said plug means against displacement
from said port means and releasable in response to said increased
control fluid pressure.
10. The device of claim 9 wherein said plug is a disk sealingly
disposed in said port and being displaceable from such sealing
position by said increased control fluid pressure.
11. The device of claim 9 in combination with a supplementary
safety valve disposed therein and actuated by control fluid
pressure conducted to the same through said control fluid
passage.
12. The device of claim 9 wherein said plug in said port has its
inner and outer sides subjected to control fluid pressure when said
sleeve is in said inoperative position.
13. The device of claim 12 in combination with a supplementary
safety valve disposed therein and actuated by control fluid
pressure conducted to the same through said control fluid
passage.
14. The device of claim 9 wherein said plug in said port has its
inner and outer ends subjected to well fluid pressure when said
sleeve is in said inoperative position.
15. The device of claim 14 in combination with a supplementary
safety valve disposed therein and actuated by control fluid
pressure conducted to the same through said control fluid passage.
Description
This invention relates to well flow control valves and more
particularly to subsurface automatic safety devices for controlling
the flow of fluids through flow conductors in wells and which may
be responsive to the flowing well fluids for operation or may be
surface controlled.
The invention illustrated and described hereinbelow is an
improvement over the well control valves illustrated and described
in U.S. Pat. No. 3,696,868 issued to Donald F. Taylor, Jr. on Oct.
10, 1972. It is also an improvement over the subsurface safety
shut-off valve apparatus illustrated and described in U.S. Pat. No.
2,998,077 issued to Julian D. Keithahn on Aug. 29, 1961.
It is one object of this invention to provide a subsurface safety
valve having means for holding the valve in open position or in a
position intermediate open and closed positions.
It is a particular object of this invention to provide a well flow
control valve including means for installing a supplementary valve
therein after the original valve has first been locked in an
inoperative position.
Another object of this invention is to provide in a valve of the
character just described means for operating the valve by control
fluid pressure conducted thereto from the surface.
A further object of this invention is to provide a valve of the
character just described having lateral control fluid passage means
leading into the interior of the valve so that a supplemental valve
disposed in the first valve may be controlled also by the same
control fluid pressure.
Another object of this invention is to provide means in said
control fluid passage normally blocking admission of control fluid
into the interior of the valve but which is openable after the
original valve has been locked in an open or in an intermediate
position.
Other objects and advantages will become apparent from reading the
description which follows and from studying the accompanying
drawing wherein:
FIGS. 1-A, 1-B, 1-C, and 1-D together form a longitudinal view,
partly in section and partly in elevation with some parts broken
away, showing a flow control valve embodying this invention in open
position;
FIG. 2 is a cross-sectional view taken along line 2--2 of FIG.
1;
FIG. 3 is a cross-sectional view taken along line 3--3 of FIG.
1;
FIG. 4 is a cross-sectional view taken along line 4--4 of FIG.
1;
FIG. 5 is an enlarged fragmentary view showing means for releasably
plugging the lateral control fluid flow passage in the device of
FIG. 1;
FIG. 6 is a fragmentary longitudinal view, partly in section and
partly in elevation with some parts broken away, showing the device
of FIG. 1 with the valve mechanism in closed position;
FIG. 7 is a fragmentary view similar to FIG. 6 showing the lock
sleeve shifted to position holding the valve open;
FIG. 8 is an enlarged fragmentary view similar to FIG. 5 showing
the plug means of the device of FIG. 1 being expended to open the
lateral control fluid passage;
FIGS. 9-A and 9-B together form a view similar to FIG. 6 showing
the latch sleeve in position holding the valve open, showing the
lateral control fluid passage open, and a supplementary flow
control valve disposed in the original device of FIG. 1 for
controlling well flow therethrough;
FIG. 10 is an enlarged fragmentary view similar to FIG. 5 but
showing disk means for closing the lateral control fluid
passage;
FIG. 11 is an enlarged view similar to FIG. 10 but showing the disk
means in ruptured condition opening the control fluid passage;
FIG. 12 is a longitudinal view, partly in section and partly in
elevation with some parts broken away, showing the upper portion
only of a modified form of device having a rupture disk closing the
lateral control fluid passage therein, control fluid pressure
normally existing on both sides of the disk;
FIG. 13 is a fragmentary view similar to FIG. 12 showing the device
of FIG. 12 with the lock sleeve in position holding the valve open
and the lateral control fluid passage open, the disk therein having
been ruptured;
FIG. 14 is a view similar to FIG. 12 but showing a further modified
form of the invention having rupturable disk means closing the
lateral control fluid passage therein, the disk being carried in
the shiftable latch sleeve, well pressure normally existing on both
sides of the disk; and
FIG. 15 is a view similar to FIG. 13 showing the device of FIG. 14
with the lock sleeve in position holding the valve open and the
lateral control fluid passage open, the rupture disk therein having
been ruptured.
Referring now to FIGS. 1 through 8 of the drawing, it will be seen
that the device of this invention is indicated generally by the
numeral 20. It includes a housing 25 which is externally threaded
at its lower end at 21 for attachment to the lower portion T-1 of a
string of tubing T and internally threaded at its upper end as at
22 for attachment to the lower threaded end of a landing nipple 23
which is internally threaded as at 24 for attachment to the upper
portion T-2 of the string of tubing T. Thus, the device 20 is
connectable in a well flow conductor to become a part thereof.
Near its upper end, the housing 25 is provided with a longitudinal
eccentric flow passage 26 which is threaded at its upper end as at
27 for attachment of the lower end of a control fluid conductor 28
extending downwardly from the surface control unit 29 which is
located on the surface and furnishes pressurized control fluid for
transmission through the control fluid conductor to the valve 20 to
hold the same open to permit well products to flow upwardly
therethrough from the producing formation (not shown) to the
surface where such products are gathered and stored or disposed of
all in the usual manner.
The surface control unit 29 includes pilot means (not shown) which
will automatically relieve pressure from the control fluid conduit
28 in response to high or low pressure conditions at the wellhead
or in the flow line, or in response to abnormal conditions relating
to fire, storm, high fluid levels in storage vessels, or the like,
depending on the pilots used and how they are installed, and will
permit the valve 20 to close to block flow therethrough.
The device 20 comprises a flap valve member 30 which is swingable
about pin 31 between an open position shown in FIG. 1-D and a
normally closed position shown in FIG. 6. The flap valve member 30
is held open by tubular operator member 32 mounted in the housing
for longitudinal movement therein between a valve open position,
shown in FIGS. 1-A, 1-B, 1-C and 1-D, and a valve closed position,
shown in FIG. 6. The reciprocable operator member is provided with
an external annular piston 32a which is acted upon from above by
the pressure of the control fluid in the annular piston chamber 33
to hold the operator member down against the upward bias spring 34
and thus hold the flap valve member in its open position against
the bias of spring 31a.
When control fluid pressure is, for any reason, relieved from the
control fluid conductor 28 and, therefore, chamber 33, the spring
34 moves the operator member upwardly to its upper position and out
of the way of the flap valve member, whereupon spring 31a will
swing it to its closed position, shown in FIG. 6, wherein it
engages the seat surface 35 and stops all flow through the
valve.
It is well known that operator means such as the reciprocable
tubular operator member 32 is also well suited for operating valves
other than the flap type valve illustrated. For instance, such
longitudinally slidably operator means have been used to operate
ball-type valve closures as is illustrated and described in
aforementioned U.S. Pat. No. 3,696,868. They have also been used to
operate poppet-type valve closures as is illustrated and described
in U.S. Pat. No. 3,273,588 issued Sept. 20, 1966, to W. W.
Dollison. In fact Dollison uses his reciprocable operator means to
operate all three such types of valves. It will be noted that each
of the three types of valves is open when the operator member is
down and closed when the operator is up. Therefore, either type of
valve would be usable in the present invention, the flap type valve
being illustrated and described herein by way of explanation
only.
It may be desirable under some conditions to positively hold the
valve 30 of the device 20 open to permit tools or devices to be
lowered therethrough or to render the valve inoperative while
permitting continued production from the well. In such case, a
shifting tool, such as the shifting tool illustrated and described
in U.S. Pat. No. 3,051,243, issued Aug. 28, 1962, to George G.
Grimmer, is utilized to engage and shift the slidable lock sleeve
40 to its lower position and lock it there to hold the operator
member down and thereby hold the valve open.
If the device 20 has malfunctioned, it may be desirable to install
a packoff through it, after the sleeve 40 has first been shifted to
its lower position, to hold the valve inoperative and permit
continued production of the well. Such a packoff is installed in
the manner taught by Taylor in his U.S. Pat. No. 3,696,868
mentioned above. This packoff tool is supported on a suitable
locking mechanism disposed in the landing nipple 23 forming an
upper portion of the device 20 and seals carried by the packoff
seal between the packoff and the device 20 in the prepared bores 42
and 43 provided in the device near its upper and lower ends,
respectively, as shown in FIGS. 9-A and 9-B.
A supplementary or auxiliary flow control valve can be provided in
the packoff and its actuation can be controlled from the surface by
control fluid conducted thereto from the surface controller 29
through the control fluid conductor 28 in the same manner that
actuation of valve 20 is controlled. If such valve is to be
installed, then the sleeve 40 must be first shifted to its lower,
valve open, position, and the pressure output of the surface
controller 29 must be increased until the lateral control fluid
passage in the wall of the valve 20 is opened by the failure of
rupturable or shearable plug means which has to this time kept such
passage closed. In this manner, production of the well may be
continued in the usual manner and the supplementary will close any
time an undesired condition develops which will cause the surface
controller 29 to respond by relieving the pressure from the control
fluid conductor 28.
The housing 25 of the device 20 includes a tubular spring housing
50 which is internally threaded at its upper end as at 51 to
receive the lower threaded end 52a of the connector 52. An o-ring
53 disposed in a suitable external annular recess near the lower
end of the connector 52 seals between the connector and the sleeve
50. The upper end of the connector is externally threaded as at 54
for attachment to the lower internally threaded end of the upper
housing 55 and this connection is sealed by an o-ring 56 disposed
in a suitable external annular recess formed near the upper end of
the connector. The upper end of the upper housing 55 is internally
threaded as at 22 for attachment to the lower threaded end of the
landing nipple 23 and this connection is sealed by an o-ring 58
disposed in a suitable external annular recess formed on the
extreme lower end of the landing nipple. The upper end of the
landing nipple is internally threaded as at 24 for attachment to
the lower threaded end of the tubing section T-2 of the tubing
string T.
The landing nipple 23 is provided with landing recesses 61 formed
in the internal wall thereof to provide means for locating and
locking a suitable locking device which may be used to support a
supplementary valve, or the like, in the device 20, should the
device 20 become inoperative. One suitable locking device is that
illustrated and described in U.S. Pat. No. 3,208,531, issued Sept.
28, 1965, to Jack W. Tamplen. Below the recesses 61, the bore 42 of
the landing nipple is provided with a smooth finish adapted to
receive seal means carried by the locking device or by the
supplementary valve, or the like, mentioned above.
The upper housing 55 is provided with a small diameter longitudinal
offset or eccentric passage 26 formed near its outer edge and the
upper end of this passage is internally threaded as at 27 to
receive the lower threaded end of the control fluid conduit 28. The
lower end of the passage 26 opens into and communicates with the
enlarged bore 64 of the upper housing 55. The passage 26,
therefore, communicates the interior of the upper housing 55 with
the surface controller 29 through the control fluid conduit 28 for
a purpose to be described.
An internal flange 65 is provided in the upper housing 55 and its
upper surface 65a provides a stop shoulder which is engaged by the
lower end of the landing nipple 23. The lower surface 65b of the
flange 65 provides a stop shoulder which is engaged by the upper
end of a tubular sleeve housing 70 disposed inside the upper
housing and whose reduced upper end portion 70a is telescoped into
the intermediate bore 71 of the upper housing. An o-ring 72 is
disposed in a suitable external annular recess near the upper end
of the sleeve housing 70 and seals between the sleeve housing and
the upper housing 55 as shown in FIG. 1-A. The seal 72, therefore,
seals the upper end of the annular passage or annular chamber 75
formed between the sleeve housing and the upper housing. The lower
end of the annular passage 75 is sealed by the o-ring 56 previously
mentioned. The lower end of the sleeve housing is reduced in
external diameter as at 70b and is telescoped into the enlarged
bore 76a in the upper end of the spacer sleeve 76 and a seal ring
77 disposed in a suitable external annular recess on the lower end
of the sleeve housing seals between the sleeve housing and the
spacer sleeve.
The lower end of the spacer sleeve 76 is supported on the supper
end 52c of the connector 52 and its lower reduced bore 78 is
telescoped over the upper end of the valve operator 32 while an
o-ring 79 disposed in a suitable internal annular recess in the
wall of the reduced bore 78 of the spacer sleeve seals between the
spacer sleeve and the exterior of the operator 32. The lower end of
the spacer sleeve 76 is grooved or slotted across its lower end as
at 80 to provide a pair of radially disposed passages which conduct
control fluid from the annular space 75 exterior of the spacer
sleeve into the annular piston chamber 33 formed between the
connector and the operator 32. In this manner, control fluid is
conducted from the surface controller 29 through the control fluid
conduit 28 and through the eccentric passage 26 of the housing into
the annular space 75 between the upper housing 55 and the sleeve
housing 70 and from thence through the cross slot 80 at the lower
end of the spacer sleeve into the upper end of the piston chamber
33 where it acts downwardly on the piston 32a. The piston 32a
carries an o-ring 81 disposed in a suitable external annular recess
formed in the piston, as shown, and seals between the piston and
the inner wall 52b of the connector.
When the controller supplies control fluid at normal pressure to
the upper side of the piston, the force created against the piston
will overcome the upward bias of the spring 34 and will move the
operator 32 downwardly to the position shown in FIGS. 1-A, 1-B,
1-C, and 1-D, in which position the valve 30 will be held open to
permit fluid flow to take place through the device 20.
The lower reduced end portion 70b of the sleeve housing 70 which is
telescoped into the upper end of the spacer sleeve 76 is very short
and the enlarged bore 76a in which it is disposed is sufficiently
long to provide a recess 76b between the lower end of the sleeve
housing 70 and the upwardly facing shoulder 76c of the spacer
sleeve. This recess 76b has disposed therein a retainer ring 82
supported on the shoulder 76c and a snap ring 88 supported on the
retainer ring. The retainer ring 82 is provided with one or more
suitable apertures through the wall thereof for receiving one or
more suitable shear pins, such as the shear pin 82a, whose inner
ends are disposed in a suitable external annular recess formed in
the lower end of a shiftable lock sleeve 40 disposed within the
sleeve housing 70. The lock sleeve 40 has an internal bore 83 which
is approximately the same size as the bores through the landing
nipple and the operator assembly and, in the wall of the bore 83, a
plurality of recesses 85 are formed which are engageable by a
suitable shifting device such as the shifting tool ST by which the
sleeve is shifted downwardly to its lower position wherein it will
hold the operator assembly down and, therefore, hold the valve
open.
The shear pins 82a releasably retain the slidable lock sleeve 40 in
its upper inoperative position where it clears the upper end of the
valve operator 32 when it is in its upper position and, therefore,
will not interfere with its operation until such time that the
shiftable sleeve is moved downwardly by the shifting tool ST to
lock the valve open. At this time a downward force applied to the
sleeve through the shifting tool ST and suitable wireline tools
WLT, or the like, causes the pin or pins 82a to shear and forces
the shiftable lock sleeve to be moved downwardly relative to the
sleeve housing 70.
A buttress-like thread or longitudinally spaced circumferential
buttress-like flanges 86 are formed on the exterior of the slidable
lock sleeve 40 and extend from just above the shear pins 82a to a
point near the upper end of the sleeve and these buttress-like
flanges are engageable by complementary buttress-like flanges 88
formed in the interior of the ratchet pawl or snap ring 90 disposed
in the recess 76b between the retainer ring 82 and the lower end of
the sleeve housing 70.
The buttress-like exterior flanges 86 on the sleeve 40 are each
formed with a downwardly facing cam shoulder 86a and an upwardly
facing abrupt stop shoulder 86b. Similarly, the complementary
interior buttress-like flanges 88 in the snap ring are each formed
with an upwardly facing cam shoulder 88a and a downwardly facing
abrupt stop shoulder 88b. The snap ring is inherently sprung
inwardly to the contracted position shown in FIG. 1-A and when the
lock sleeve 40 is moved downwardly therethrough the cam surfaces
86a on the lower side of the buttress-like flanges on the sleeve
coact with the complementary cam surfaces 88a formed on the upper
side of the buttress-like flanges in the snap ring 90 so that the
downward movement of the lock sleeve 40 will cam or expand the ring
open so that the sleeve can move downwardly through the snap
ring.
When the lock sleeve 40 is for any reason thereafter biased
upwardly, the snap ring or annular pawl 90 will contract so that
the downwardly facing stop shoulders 88b of its inner buttress-like
flanges 88 will engage the complementary upwardly facing abrupt
stop shoulders 86b of the buttress-like flanges on the lock sleeve
40 to prevent further upward movement of the sleeve relative to the
snap ring and sleeve housing. The snap ring, therefore, acts as a
ratchet pawl, permitting the sleeve to be moved downwardly relative
thereto, and preventing upward movement thereof.
When the lock sleeve 40 is moved downwardly, it is preferably moved
to its lowermost position so that the valve 30 will be held fully
open. If, however, debris or the like should interfere with the
mechanism so that the valve cannot be moved to its fully open
position, or the operator assembly 32 or the lock sleeve cannot be
moved to their lowermost positions, the lock sleeve 40 will be
prevented from moving upwardly so that the operator 32 will be
locked in the lowest position reached and the valve will be held
open as wide as possible in such case.
At least one lateral passage or aperture 100 and preferably two are
provided in the wall of the sleeve housing 70 opposite the upper
end portion of the lock sleeve 40 when the lock sleeve is in its
upper position as is shown in FIG. 1-A. Each aperture 100
communicates the interior of the sleeve housing with the exterior
thereof so that control fluid from the annular passage 75 will be
conducted through the lateral passage or aperture 100 into the
interior of the lock sleeve for operation of a supplementary safety
valve subsequently placed in the device 20.
The lateral aperture 100 is provided with a large counterbore 101
providing a shoulder 101a, as is shown in FIG. 5, and a plug 102 is
disposed in the sperture 100 with its inner end surface 103 in
close proximity to the exterior surface of the lock sleeve 40 and
may even engage the same. The plug 102 is provided with a suitable
external annular recess in which is disposed an o-ring 104 which
seals between the plug 102 and the inner wall of the aperture 100.
The outer end of the plug is reduced in diameter as at 105 and a
flat washer 106 is disposed thereabout while a shear pin 107 is
disposed through a suitable aperture near the outer end of the plug
with its outer ends extending outwardly from the plug and being
engageable with the washer 106 to retain the plug in place against
inward displacement as shown. The washer 106 and the shear pin 107
are disposed within the counterbore 101 of the aperture 100. The
plug is sufficiently long so that its outer end is very close to
the inner wall 55a of the upper housing 55 to prevent its outward
displacement. Therefore, the plug is rather closely confined
between the inner wall of the upper housing 55 and the exterior of
the upper end portion of the shiftable lock sleeve 40 and cannot
move longitudinally out of its sealing position in the aperture
100. The plug will thus prevent the flow of fluids from the annular
passage 75 into the interior of the sleeve housing 70 until it is
displaced from such sealing position as will be explained
later.
When it is desired to lock the valve 30 open and render the device
20 inoperative, a suitable shifting tool such as that illustrated
and described in the aforementioned U.S. Pat. No. 3,051,243 to
Grimmer is utilized to engage the recesses 85 in the shiftable lock
sleeve 40 and to move it downwardly, moving the valve operator 32
downwardly therewith in order to swing the valve 30 to its open
position, shown in FIGS. 1-A, 1-B, 1-C and 1-D. With the shiftable
lock sleeve moved to its lower position and locked in such position
by the engagement of its exterior buttress-like flanges with the
buttress-like flanges in the snap ring, the valve cannot move from
its open position toward its closed position. Accordingly,
production of the well can be continued as desired.
When the lock sleeve 40 is moved downwardly from its upper position
shown in FIG. 1-A and the upper end thereof clears the plug 102
which is disposed in the aperture 100, the control fluid pressure,
conducted to the valve 20 from the surface controller 29 through
the control fluid conduit 28 and through the longitudinal eccentric
passage 26 in the upper housing to the annular chamber 75, will act
on the plug 102 and tend to move it inwardly to displace it from
its sealing position in the aperture 100. This displacement cannot
at this time take place because the washer 106 will then engage the
bottom 101a of the counterbore 100 and the outer ends of the shear
pin 107 will engage the washer 106 to prevent further inward
movement of the plug 102. Thus, it may be readily seen that the
plug will remain intact since the shear value of the shear pin
exceeds the forces developed by normal control fluid pressure
acting across the plug. If, however, it is desired to install a
supplementary safety valve within the valve device 20 and to
control such supplementary valve by control fluid pressure
conducted thereto from the surface controller 29, it is only
necessary to increase the control fluid pressure to a value
substantially above normal until such increased pressure is
sufficient to shear the shear pin 107 and permit the plug 102 to
move inwardly out of aperture 100 as shown in FIG. 8, and into the
central bore of the device 20 where it will fall harmlessly to the
bottom of the wall.
In the absence of the plug 102, the aperture 100 will be open and
control fluid pressure can pass freely from the chamber 75 into the
interior of the sleeve housing 70.
A supplementary safety valve such as the valve 120 is then attached
to the lower end of a suitable locking device such as the locking
device 121 and lowered into the wall on a suitable running tool and
string of wireline tools (not shown) and installed as shown in
FIGS. 9-A and 9-B. The locking device 121 has keys 122 having
bosses 123 which engage in the lock recesses 61 of the landing
nipple 23 and support the valve 120 therein in the proper position.
Suitable seal rings 124 carried by the locking device 121 seal
between the device and the inner wall 42 of the landing nipple
while suitable seals 125 carried on the valve 120 near the lower
end thereof engage the inner wall 43 of the lower sub 45 at the
lower end of the safety valve device 20 to seal between the lower
end of the supplementary safety valve 120 and the lower portion of
the safety valve device 20. Thus, control fluid passing through the
open aperture 100 in the sleeve housing 70 is confined to the
region between the supplementary valve 120 and the inner wall of
the device 20 between the upper and lower seal assemblies 124 and
125. This control fluid is then conducted through the inlet port
128 into the mechanism of the supplementary valve for actuation of
the same. Thus, the flow of well fluids through the well tubing T
is controlled by controlling the supplementary valve from the
surface in exactly the same manner as was the valve device 20.
When suitable pilot means (not shown) in the surface controller 29
responds to a particular condition and acts to bleed or relieve the
control pressure from the control fluid conduit 28, the
supplementary valve 120 will close to stop flow through the valve.
When such particular condition has been cleared up and the surface
controller 29 used to reinstate control pressure to the system, the
valve 120 will open so that production from the well may be
continued in the usual manner.
Thus, it has been shown that a subsurface safety valve has been
provided which is controllable from the surface and which can be
locked in open position by sliding a shiftable lock sleeve
downwardly which will force the operator downwardly and, therefore,
force the valve closure member to its open position; that the lock
sleeve can be locked in its lowermost or any intermediate position
so that upward movement of the lock sleeve from such position is
not possible; that such valve can be locked in open position and
production continued from the well if desired; that a supplementary
valve can be installed in the safety valve device and supported
from a suitable lock mandrel and that such supplementary safety
valve can be controlled from the surface in the same manner as was
the original safety valve but before such supplementary valve is
installed; that prior to installation of such supplementary valve,
the control pressure is temporarily raised to a much higher than
normal level to open up a passage or port means in the valve
mechanism and establish means for admitting control fluid into the
inner bore of the device where the supplementary safety valve is
disposed. Of course, it si understood that a packoff mechanism or
other tool can be installed in place of the supplementary safety
valve to packoff a faulty valve such as the safety valve device 20,
in which case the locking mandrel 121 would carry an open bore
valveless tubular body between the upper and lower seal assemblies
124 and 125 to that production fluids would be conducted
therethrough past the faulty valve. If such packoff tool is used,
it is not necessary to conduct control fluid thereto; so the plug
102 is left intact in its place closing the lateral aperture 100. A
packoff tool is usable, for instance, in cases where the control
fluid conduit 28 breaks, and also at the same time, a failure
occurs in the plug 102 or in the seals 124 or 125 of the safety
valve such that well fluids otherwise escape from the well tubing
through the faulty safety valve and through the broken control
fluid conduit 28 into the surrounding casing which may not be able
to withstand high well pressures. A packoff tool thus prevents such
leakage and permits continued production from the well but without
protection previously afforded by the surface controlled downhole
safety valve 20.
A modified form of the invention is illustrated in FIGS. 10 and 11
where it is indicated generally by the numeral 150.
In this form of the invention, the upper housing section 55, having
the offset or eccentric control fluid passage 26, has mounted
therein a modified sleeve housing 151. This sleeve housing has at
least one lateral aperture or control fluid passage 152 formed in
its wall and this aperture is enlarged as at 153 providing a
seating surface 154 and is internally threaded as at 155 to receive
a plug 156 having its inner end portion 157 reduced in diameter to
fit within the aperture 152 and to provide a seal surface 158 which
engages the seating surface 154 of the aperture to prevent leakage
of control fluid around the plug.
The plug 156 is provided with a bore 160 therethrough and this bore
is enlarged as at 161 to provide a stop shoulder 162. A sealing or
rupture disk 164 is disposed in the enlarged bore 161 of the plug
and engaged against the stop shoulder 162 where it is sealingly
secured in place by silver solder, epoxy cement, or the like, to
seal the plug bore 160 against leakage of control fluid
therethrough. If desired, the disk may be dished or cupped and its
convex surface faced inwardly as is clearly shown in FIG. 10.
It will be noted that the inner side 164a of the sealing or rupture
disk is substantially in engagement with the exterior wall surface
of the shiftable sleeve 40 which helps to support the disk against
premature rupture or displacement from its sealing position,
although the disk is preferably sufficiently strong to make such
support normally unnecessary.
If, after the shiftable lock sleeve 40 has been shifted to its
lower position to force the valve 30 open and to hold it in this
open position, it is desired to install a supplementary device,
such as the supplementary safety valve 120, in the device 150, the
control fluid pressure is increased until the disk 164 is displace
or ruptured to open the bore 160 through the plug 156 as shown in
FIG. 11, thus providing a lateral control fluid passage through the
wall of the sleeve housing 151. Subsequently, the supplementary
safety valve is installed and actuated from the surface as before
explained.
Thus, it will be seen that the plug 156 of the device 150 serves
exactly the same function as does the plug 102 of the device 20
previously described and that the lateral aperture 100 of the
device 20 and the aperture 152 of the device 150 each are opened in
exactly the same manner, that is, by increasing the control fluid
pressure until the plug fails, opening the lateral control fluid
passage.
Another modified form of the invention is illustrated in FIGS. 12
and 13 where it is indicated generally by the numeral 200. The
device 200 may be exactly like the devices previously described
below its connector 52 in whose bore the piston 32a is slidable.
Above the connectors 52 there are substantial differences in
structure. For this reason, only the upper portion of the device
200 is shown.
The upper housing 201 is substantially the same as the upper
housing 55 of the device 20 first described but is considerably
longer. The upper housing 201 is threadedly attached at its lower
end to the upper threaded end of the connector 52 and its upper end
is internally threaded as at 204 for attachment to the landing
nipple 23. An eccentric of offset longitudinal control passage 206
is provided in the upper portion of the upper housing 201 and is
threaded as at 207 at its upper end for attachment of the control
fluid conduit 28. The passage 206 has its lower end opening into
the enlarged bore 210 of the upper housing. Thus, control fluid is
conducted from a surface controller such as the surface controller
29 on the surface through the control fluid conduit 28 to the
device 200 where it enters through the passage 206 and from there
is conducted to the valve mechanism as will be described.
A sleeve housing 215 is disposed within the upper housing 201 and
its reduced upper end portion 216 is telescoped into the
intermediate bore 217 in the upper portion of the upper housing 201
as shown. A seal ring such as the o-ring 218 is disposed in a
suitable external annular recess near the upper end of the sleeve
housing 215 and seals between the upper end of the sleeve housing
and the upper housing. The outside diameter of the sleeve housing
215 is somewhat less than the inside diameter of the upper housing
so that an annular space or passage 220 is provided between the
sleeve housing and the upper housing. It is readily seen that the
o-ring 218 seals the upper end of this annular passage 220. The
lower end portion 222 of the sleeve housing is reduced in diameter
and is telescoped into the enlarged portion 224 of the bore 226 of
the spacer sleeve 228 while a seal ring such as the o-ring 229
seals between the sleeve housing and the spacer sleeve as shown.
The lower end of the spacer sleeve 228 is supported upon the upper
end of the connector 52 and is provided with a groove or slot 230
across its lower end to provide a radial passage through which
control fluid may be conducted from the annular passage 220 into
the piston chamber 2 where it acts downwardly upon the piston 32a
to move the valve operator 32 down for opening the valve.
As in the preceeding embodiment, the spacer sleeve is telescoped
over the upper end of the valve operator 32 and a seal ring such as
the o-ring 232 disposed in a suitable internal annular recess
formed in the spacer sleeve seals between the spacer sleeve and the
exterior of the valve operator to close the upper end of the piston
chamber 33.
Thus, control fluid is conducted from the offset or eccentric
passage 206 into the upper end of the annular passage 220 and from
the annular passage 220 through the cross slot or groove 230 of the
spacer sleeve into the chamber 33 to operate the piston.
An elongate slidable lock sleeve 240 has its upper portion disposed
in the sleeve housing 215 and its lower portion extending down into
the spacer sleeve 228 as shown. The upper portion of the lock
sleeve is provided with external buttress-like flanges or threads
241 which may be exactly like the external flanges 86 on the lock
sleeve 40 of the device 20. The lock sleeve 240 is also provided
with a plurality of suitable internal annular recesses 85 which are
engageable by a suitable shifting tool such as the shifting tool ST
previously mentioned for shifting the sleeve to a lower position
for holding the valve open or in an inoperative position as was
before explained.
A seal ring such as the o-ring 242 is disposed in a suitable
external annular recess near the upper end of the shiftable lock
sleeve to seal between the lock sleeve and the sleeve housing. A
seal ring such as the o-ring 243 is disposed in a suitable internal
annular recess formed in the mid portion of the spacer sleeve 228
to seal between the spacer sleeve and the lower end of the slidable
lock sleeve 240. A seal ring such as the o-ring 244 is disposed in
a suitable external annular recess formed in the mid portion of the
lock sleeve. When the sleeve is in its upper position as shown in
FIG. 12, the seal ring 244 does not seal between the slidable lock
sleeve and the spacer sleeve because the seal ring 244 is disposed
in a slightly enlarged intermediate bore 246 in the spacer sleeve
between the main bore 226 and the enlarged bore 244 where it is
ineffective to provide a seal.
The enlarged bore 224 at the upper end of the spacer sleeve is
considerably longer than the length of the reduced portion 222 of
the sleeve housing, telescoped thereinto thus providing a wide
internal annular recess 250 between the lower end of the enlarged
bore 224 and the lower end of the sleeve housing 215.
A retainer ring 251 having one or more apertures 252 through the
wall thereof is disposed in the lower part of the recess 250 and
carries one or more shear pins 253 disposed in such apertures, each
shear pin having its inner end disposed in a suitable external
annular groove formed in the mid portion of the shiftable lock
sleeve 240 to retain the shiftable sleeve in its upper inoperative
position shown in FIG. 12. Between the retainer ring 251 and the
lower end of the sleeve housing 251, a snap ring or annular pawl 90
is disposed in the internal annular recess 250 and this snap ring
may be exactly the same as the snap ring 90 in the device 20
previously described and which is shown in FIG. 1-A. The snap ring
is provided as before explained with internal buttress-like
projections and the exterior of the upper portion of the shiftable
lock sleeve 240 is formed with complementary exterior buttress-like
projections which may be exactly like those on the sleeve 40 in the
device 20 previously described.
The shiftable sleeve 240 is shifted to its lower position through
use of a suitable shifting tool such as the shifting tool ST which
engages the internal recesses 85 in the shiftable sleeve and when a
downward force of sufficient magnitude is applied to the sleeve,
the pins 253 are sheared and the sleeve moved downwardly, the lower
end of the sleeve contacting the upper end of the operator 32, if
the operator is in an upper position, and forcing the operator 32
downwardly to a lower position wherein it holds the valve (not
shown) open. During downward movement of the lock sleeve 240, the
external buttress-like flanges thereon cam their way through the
snap ring 90 which is inherently sprung inwardly and when the
sleeve reaches a lower position any tendency for it to move
upwardly thereafter will result in engagement of the abrupt
surfaces on the complementary buttress-like flanges of the sleeve
and snap ring, thus preventing further upward relative movement of
the sleeve. Thus, the shiftable sleeve is locked in a lower
position holding the valve open.
It will be noted that the sleeve housing 215 is provided with a
lateral port or passage 270 near its upper end and that this port
is closed with a plug 271 which may be exactly like the plug 102 in
the device 20, or like the plug 156 in the device 150 as shown. The
plug 271 prevents the passage of control fluid from the annular
passage 220 exterior of the sleeve housing to the interior
thereof.
It will further be noticed that the spacer sleeve 228 is provided
with a lateral aperture 276 located immediatelyabove the seal ring
243 in the mid portion of this spacer sleeve. When the shiftable
lock sleeve 240 is immediately above its upper inoperative
position, as is shown in FIG. 12, control fluid conducted to the
device 200 through the control fluid conduit 28 passes through the
eccentric or offset passage 206 into the annular passage 220
between the upper housing 201 and the sleeve housing 215 and from
the annular passage through the cross slots 230 at the lower end of
the spacer sleeve into the piston chamber 33 for operation of the
piston and actuation of the valve.
Control pressure can also pass from the annular passage 220 through
the lateral aperture 276 in the spacer sleeve but cannot move
downwardly past the seal ring 243. It can, however, move upwardly
between the exterior of the lock sleeve 240 and interior of the
spacer sleeve 228 and past the seal ring 244 which is spaced from
the inner wall of the immediate bore 246 and can pass beyond the
retaining ring 251 and the snap ring 90 and upwardly between the
shiftable lock sleeve 240 and the interior of the sleeve housing
215 as far as the seal ring 242. The control pressure thus acts on
the inward side of the plug 271 and at the same time acts on the
outward side of the plug since the outward side is clearly exposed
to fluid in the annular passage 220. It will thus be seen that when
the lock sleeve 240 is in its upper position, as shown in FIG. 12,
the plug is isolated from well fluids and no differential pressure
can act on it to shear or displace the same since its ends are
exposed to a common pressure, namely, control fluid pressure.
When the shiftable sleeve 240 is moved to its lowermost position as
is shown in FIG. 13, the seal ring 244 carried by the lock sleeve
comes to rest in sealing position above the lateral aperture 276 in
the spacer sleeve, thus preventing control fluid pressure from
moving upwardly therepast. At the same time, when the sleeve has
been moved downwardly, the seal ring 242 carried near the upper end
of the sleeve moves out of its sealing position above the lateral
apertue 270 in the wall of the sleeve housing and clears the plug
271, thus allowing well pressure to come to bear against the inner
side of the plug 271. The plug now has its inner end exposed to
well pressure while its outer end is still exposed to control fluid
pressure.
When the shiftable sleeve 240 is in its lower position as shown in
FIG. 13, the device 200 is understandably held inoperative, the
shiftable sleeve being locked by the snap ring in its lower
position holding the valve operator 32 down and thus holding the
valve open.
If it is desired to install a supplementary safety valve, such as
the supplementary safety valve 120 in the device 200 and to control
it from the surface, it will be necessary to raise the control
fluid pressure to a level which will cause the plug 271 to fail,
thus opening the lateral passage 270 through the wall of the sleeve
housing and admit cntrol fluid pressure into the interior of the
device 200 in the manner already described.
The advantages of the structure just described and which is shown
in the FIGS. 12 and 13 are that, under normal conditions when the
shiftable sleeve 240 in its upper position and the plug 271 is
intact, the plug has clean noncorrosive control fluid on both of
its sides and is isolated from well fluids which may be corrosive
and ladened with abrasive particles, etc., and the plug will not be
subjected to pressure differentials.
A further modified form of the invention is illustrated in FIGS. 14
and 15 and is there indicated by the number 300. This form of the
invention is very similar to the form last described and its lower
portion from the connector 52 of the housing downwardly is exactly
the same as the embodiments previously described. Attached to the
upper end of the connector 52 is an upper housing 301 which may be
exactly like the upper housing 201 of the previous embodiment and
this upper housing 301 is threadedly attached to the lower end of
the landing nipple 23 thereabove and has an offset or eccentric
longitudinally disposed control fluid passage 303 connected at its
upper end to the control fluid line 28 and its lower end opening
into the enlarged bore 310 of the upper housing as in the previous
embodiments. Disposed within the upper housing is a sleeve housing
312 which is similar to the sleeve housing 215 in the embodiment
previously deacribed but is not provided with an aperture in the
wall thereof. The upper reduced portion 314 of the sleeve housing
is telescoped into the intermediate bore 315 of the upper housing
and a seal ring such as the o-ring 316 seals between the upper end
of the sleeve housing and the upper housing. The outside diameter
of the sleeve housing 312 is somewhat less than the inside diameter
of the upper housing, thus providing an annular passage 320
therebetween. The lower reduced diameter position 321 of the sleeve
housing is telescoped into the enlarged bore 322 at the upper end
of the spacer sleeve 324 and a seal ring such as the o-ring 325
seals between the sleeve housing and the spacer sleeve.
The length of the reduced diameter portion 321 on the lower end of
the sleeve housing 312 is somewhat shorter than the length of the
enlarged bore 322 in which it is received, thus providing a wide
internal annular recess 350.
A retainer ring 352 having one or more radial apertures in its wall
is disposed in the annular recess 350 and one or more shear pins
354 have their outer ends disposed in the one or more apertures in
the retainer ring 352 while their inner ends are engaged in a
suitable external annular recess formed in an elongate shiftable
lock sleeve 340 having its upper portion disposed in the sleeve
housing 312 and its lower portion extending down into the spacer
sleeve 324 as shown in FIGS. 14 and 15. The pins 354 obviously
retain the lock sleeve in its upper inoperative position shown in
FIG. 14.
An elongate shiftable or slidable lock sleeve 340 is provided with
a plurality of internal recesses 85 which are engageable by a
suitable shifting tool such as the shifting tool ST previously
mentioned for shifting the sleeve from the upper portion shown in
FIG. 14 to its lower position shown in FIG. 15. The slidable lock
sleeve 340, like the lock sleeves 40 and 240 of the devices 20 and
200, previously described, has external buttress-like flanges or
threads 364 formed about its upper portion, each such flange or
thread having a lower side which slopes downwardly and inwardly to
provide a cam surface indicated by the numeral 364a.
A ratchet pawl in the form of a snap ring 90, which may be
identical with the snap rings 90 previously described is disposed
in the recess 350 above the retainer ring and has ratchet teeth of
flanges 365 formed therein, each such flange having its upper side
sloping downwardly and inwardly to provide a cam surface indicated
by the numeral 365a which cooperates with the cam surfaces 364a on
the flanges of the lock sleeve 340 as will be explained.
The lock sleeve 340 is shifted to a lower position to hold the
valve open by lowering a suitable shifting tool into the well flow
conductor, engaging it in the recesses 85 in the lock sleeve 340
and applying a downward force thereto. This downward force shears
the pins 354 in the retainer ring 352 and moves the lock sleeve
downwardly through the snap ring 90. During downward movement of
the lock sleeve, the cam surfaces 364a on the lower sides of its
external buttress-like flanges coact with similar cam surfaces 365a
on the upper sides of complementary flanges in the snap ring to
force open the snap ring and permit the lock sleeve to move
downwardly therethrough. When the slidable lock sleeve 340 reaches
its lower position as is shown in FIG. 15, or an intermediate
position, it is locked in such position by the pawl snap ring 90
and holds the valve operator member 32 in such lower position and
thus holds the valve (not shown) in open position as was previously
described.
Control fluid is conducted to the device 300 for holding the valve
therein open, such control fluid passing through the control fluid
conduit 28 connected to the upper housing and through the eccentric
passage 303 into the enlarged bore 310 of the upper housing section
and being conducted through the annular passage 320 between the
upper housing 301 and the sleeve housing 312 and spacer sleeve 324
until it passes through the cross slot 330 formed in the lower end
of the spacer sleeve and into the piston chamber 33 where it acts
downwardly on the piston 32a for actuating the valve (not shown)
therebelow.
The spacer sleeve 324 is provided with a lateral passage or
aperture 332 formed in the wall thereof and a pair of seal rings
such as the seal rings 334 and 335 disposed in suitable internal
annular recesses formed in the inner wall of the spacer sleeve 324
seal between the spacer sleeve 324 and the exterior of the lower
portion of the shiftable sleeve 340 above and below the lateral
aperture 332, respectively, so that control fluid passing from the
annular passage 320 through the lateral aperture 332 is confined
between the two seal rings 334 and cannot move therepast.
The lock sleeve 340 is provided with a lateral aperture 375 through
its wall located just below the shear pin groove formed in the
exterior thereof and this aperture may be closed by any suitable
means such as one of the plugs previously described or may be
sealed by a suitable disk such as the disk 377 secured therein much
like the disk 164 is secured in place in plug 156 of the device of
FIGS. 10 and 11. It will be noted that the disk 377, when the
shiftable sleeve 340 is in its upper position shown in FIG. 14, is
in a well fluid environment since the inner side of the disk is
exposed to well fluids existing in the bore of the lock sleeve 340
and its outward face is exposed to well fluids conducted thereto
from the bore of the shiftable sleeve 340 since such well fluids
can pass around the upper end of the lock sleeve and downwardly
between it and the sleeve housing, past the snap ring and the
retainer ring, and between the shiftable sleeve 340 and the spacer
sleeve 324 as far as the upper seal ring 334 located just above the
lateral port 332 in the spacer sleeve. Thus, during normal
operation of the well, the disk 377 or other suitable plug which
may be used in place thereof is not subjected to differential
pressures and therefore there is no tendency for the same to be
displaced or ruptured prematurely. The plug or disk is obviously
isolated from control fluid pressure.
When the shiftable sleeve 340 is moved to its lower position
wherein it is locked in such position by the snap ring 90 and
wherein it holds the valve operator 32 in its lower position to
lock the valve therebelow open, the aperture 375 in the wall of the
lock sleeve will then be located between the two o-rings 334 and
335 in the wall of the spacer sleeve and, therefore, will be in
direct communication with the aperture 332 in the wall of the
spacer sleeve. Control fluid pressure may then be conducted through
the aperture 332 in the spacer sleeve into the sleeve between the
spacer sleeve and the exterior of the lock sleeve and into the
aperture 375 where it will act against the outer face of the disk
377 or against the outer end of such other suitable plug as may be
used in lieu of the disk 377. The disk or plug, whichever is used,
should preferably be sufficiently strong to withstand normal
control fluid pressures. If, however, a supplementary subsurface
safety valve such as the supplementary safety valve 120 is to be
installed in the device 300 and is to be controlled from the
surface, then prior to the installation of such supplementary
safety valve the control pressure must be increased until such
control pressure acting on the disk 377 will cause the disk to be
ruptured or be displaced from its place in the aperture 375 of the
shiftable sleeve 340, thus opening the aperture or lateral passage
375 so that control fluid pressure will be conducted to the
interior of the lock sleeve 340 where it can act on the
supplementary safety valve 120 to actuate the same.
From the foregoing it will be seen that a subsurface safety valve
for well flow conductors has been provided which is operated by
control fluid pressure conducted thereto from a surface controller
located on the surface of the earth; that the safety valve has
means therein for locking the valve mechanism in an open or
inoperative position or in an intermediate position between closed
and open positions; that the safety valve also has means therein
responsive to control fluid pressure for opening a fluid passage
into the interior of the safety valve by increasing the control
pressure substantially above normal after the locking means has
first been moved to position locking the valve mechanism in an open
or partly open position; and that a supplementary safety valve may
then be installed in the original valve and actuated by control
fluid pressure from the surface conducted thereto through the newly
opened passage. Further, it has been shown that such pressure
responsive means for opening the control fluid passage into the
interior of the safety valve may be a plug, a disk, or a disk in a
plug, or the like; that the plug or disk can be carried in the
housing or in a slidable sleeve; that such plug or disk may
normally be disposed in an environment of well fluids, or of
control fluid, or disposed so that one of its ends is exposed to
well fluids and the other of its ends is exposed to control fluid;
and that, in either case, the plug or disk can be displaced or
opened only after the slidable sleeve has been moved or shifted
from its inoperative position to a position engaging the valve
mechanism to hold the valve open or partly open.
Thus, the subsurface safety valve of this invention fulfills all of
the objects set forth in the beginning.
The foregoing description of the invention is explanatory only, and
changes in the details of construction illustrated may be made by
those skilled in the art, within the scope of the appended claims,
without departing from the true spirit of the invention.
* * * * *