U.S. patent number 3,860,066 [Application Number 05/301,525] was granted by the patent office on 1975-01-14 for safety valves for wells.
This patent grant is currently assigned to Otis Engineering Corporation. Invention is credited to Joseph L. Pearce, Phillip S. Sizer, Donald F. Taylor.
United States Patent |
3,860,066 |
Pearce , et al. |
January 14, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
SAFETY VALVES FOR WELLS
Abstract
Well safety valves for shutting off flow in a well tubing string
such as a production string or a drilling string responsive to
either predetermined low pressures or high pressures and also in
response to certain valve malfunctions. The valves include valve
operators useful with a ball, poppet, or flapper valve, and biased
toward a closed position by a spring and gas pressure on a piston
movable in a dome chamber. During normal operations, the valves are
each held open by either a tubing-casing annulus pressure or
pressure in a control line directed to a chamber applying a control
pressure to the piston opposing the dome pressure. Special seals
and chambers are included in the valves to effect pressure
equalizations causing valve closure when any one or more of the
seals leak. Additionally, certain embodiments of the valves include
means operative responsive to predetermined high pressures to
equalize the pressures in the dome chamber and the tubing-casing
annulus effecting valve closure. Some embodiments of the valves
include safety piston structure for effecting such valve closure
responsive to a predetermined high tubing-casing annulus or control
line pressure such as when valve malfunction precludes normal
closure. The valves are particularly useful in well systems for
both primary and secondary production, for certain subsea well
producing systems, and also in well drilling systems for well
testing purposes, shutting in wells, and the like.
Inventors: |
Pearce; Joseph L. (Dallas,
TX), Sizer; Phillip S. (Dallas, TX),
Taylor; Donald F. (Dallas, TX) |
Assignee: |
Otis Engineering Corporation
(Dallas, TX)
|
Family
ID: |
26931635 |
Appl.
No.: |
05/301,525 |
Filed: |
October 27, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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238397 |
Mar 27, 1972 |
|
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Current U.S.
Class: |
166/72; 137/529;
137/458; 166/324 |
Current CPC
Class: |
E21B
34/08 (20130101); E21B 34/101 (20130101); E21B
2200/04 (20200501); Y10T 137/7905 (20150401); E21B
2200/05 (20200501); Y10T 137/7725 (20150401) |
Current International
Class: |
E21B
34/00 (20060101); E21B 34/08 (20060101); E21B
34/10 (20060101); E21b 033/03 (); E21b
043/12 () |
Field of
Search: |
;166/224S,224
;137/458,529,540 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Leppink; James A.
Attorney, Agent or Firm: Garland; H. Mathews
Parent Case Text
This application is a continuation-in-part of our application Ser.
No. 238,397 entitled SAFETY VALVES FOR WELLS filed Mar. 27, 1972,
now abandoned.
Claims
What is claimed is:
1. A device for controlling fluid flow in a flow conductor of a
well comprising: a valve housing having a longitudinal bore
defining a flow passage therethrough; means for communicating
control fluid pressure to said device; valve means supported in
said housing adapted to be opened and closed to control fluid flow
through said housing; valve operator means supported for
longitudinal movement in said housing and operatively connected
with said valve means for opening and closing said valve means,
said operator means having a longitudinal flow passage
communicating with said flow passage through said housing; means
for applying a force to said operator means for biasing said
operator means in a direction to close said valve means; pressure
responsive valve opening and holding means operatively connected
with said operator means for biasing said operator means toward a
position to hold said valve means open responsive to a first
control fluid pressure level; and means between said housing and
said operator means operative responsive to a second higher control
fluid pressure level for deactivating said valve opening and
holding means whereby said valve means is closed when control fluid
pressure applied to said device exceeds said second higher pressure
level.
2. A device in accordance with claim 1 including a control fluid
conduit connected with said device for directing control fluid
pressure from a surface positioned fluid control system to said
pressure responsive means for operating said device from the
surface end of a well.
3. A device in accordance with claim 1 wherein said means for
biasing said operator means in a direction to hold said valve means
closed includes means defining a dome gas chamber adapted to be
charged to a predetermined pressure to apply a gas pressure to said
operator means and a spring engaged between said housing and said
operator means for applying a force to said operator means.
4. A device in accordance with claim 3 including first chamber
means provided at a first end of said dome chamber on the opposite
side of said pressure responsive means from said dome chamber
adapted to be sealed at a predetermined pressure lower than the
pressure in said dome chamber; said pressure responsive means being
exposed to the pressure in said first chamber means; second chamber
means provided at the other end of said dome chamber; a slidable
safety piston disposed in said second chamber means; seal means
between said piston and said operator means and said housing, said
piston and said second chamber means being sized to permit sealing
said second end of said dome chamber by said piston at a first
position of said piston and providing communication around said
piston into said second end of said dome chamber at a second
position of said piston; and said housing having means
communicating with said second chamber means on the opposite side
of said piston from said dome chamber whereby said piston is
exposed to pressure for displacing said piston toward said dome
chamber responsive to a predetermined pressure differential between
a pressure applied exterior of and the pressure within said dome
chamber.
5. A device in accordance with claim 3 including piston means on
said operator means defining a first end of said dome gas chamber;
means defining a first control chamber at said first end of said
dome gas chamber on the opposite side of said piston means from
said dome gas chamber, said first control chamber being sealed at a
pressure below the pressure in said dome gas chamber; seal means
between said housing and said operator means sealing an opposite
second end of said dome gas chamber; means defining a second
control chamber between said operator means and said housing at
said second end of and separate from said dome gas chamber; a pair
of coengaged first and second pistons in said second control
chamber, said first piston being movable toward said second end of
said dome chamber; an operating flange on said operator means
within said second control chamber and engageable by said first
piston for moving said operator means to close said valve
responsive to movement of said first piston toward said dome gas
chamber; said second piston being movable away from said dome gas
chamber and being engageable with said operator means for moving
said operator means in a direction to open said valve; releasable
coupling means between said second piston and said operator means
for releasing said operator means from said second piston to permit
said operator means to move in a direction to close said valve
independently of said second piston; said housing having flow
passage means into said second control chamber between said first
and second pistons for applying a control pressure against said
second piston to bias said valve toward an open position at a
pressure above a predetermined minimum and for urging said first
piston in a direction away from said second piston for moving said
operator means in a direction to close said valve responsive to a
control pressure in excess of a predetermined maximum.
6. A device in accordance with claim 3 wherein a portion of said
pressure responsive means exposed to said control fluid pressure at
a first end of said dome chamber is smaller in area than another
portion of said pressure responsive means exposed to the pressure
in said dome chamber whereby the pressure in said dome chamber may
be maintained at a minimum; chamber means defined at a second end
of said dome chamber between said operator means and said housing;
said housing being provided with passage means into said chamber
means; and piston means movably disposed in said chamber means for
sealing said chamber means at a first position of said piston means
and for communicating said second end of said dome gas chamber
through said chamber means to said passage means at a second
position of said piston means when said piston means is disposed to
said second position by pressure applied through passage means.
7. A device in accordance with claim 6 including releasable means
between said piston means and said housing for holding said piston
means at said first sealing position until the pressure applied
through said flow passage means exceeds a predetermined level.
8. A device in accordance with claim 6 including means defining a
pressure chargeable chamber around said annular piston between a
head portion and a skirt portion of said piston defined between a
sealed area of said head portion and a sealed area of said skirt
portion whereby the operating characteristics of said piston are
varied by changes in the pressure within said chamber.
9. A device in accordance with claim 3 wherein said operator means
includes a piston forming a movable closure at a first end of said
dome gas chamber and the second end of said dome gas chamber is
closed by seal means exposed on one side to the pressure of gas in
said dome chamber; said housing is provided with passage means
communicating with the other side of said seal means at said second
end of said dome chamber; and at least one of said piston and said
seal means includes said deactivating means for effecting closure
of said valve means responsive to said second higher control
pressure.
10. A device in accordance with claim 3 wherein said deactivating
means comprises means responsive to a predetermined high pressure
for displacing seal means to non-sealing portions on at least one
of said piston and said seal means at said second end of said dome
chamber for equalizing the pressures on opposite sides of said
piston to permit said spring to move said operator means to close
said valve when said pressure is applied to said one of said seal
means.
11. A device in accordance with claim 10 including seal means
between said valve operator means and said housing on the opposite
side of said piston from said dome chamber and seal means between
said valve operator means and said housing on the opposite side
from said dome chamber of said passage means communicating with
said seal means at said second end of said dome gas chamber.
12. A device in accordance with claim 9 wherein a side of said
piston opposite said dome chamber and said passage means at said
second end of said dome chamber are adapted to communicate directly
with the tubing-casing annulus of a well when said device is in
operating position in said well.
13. A device in accordance with claim 9 including conduit means
connected with said device communicating with a side of said piston
opposite said dome chamber and said passage means at said second
end of said dome chamber for conducting control fluid under
pressure from a surface system independently of the tubing-casing
annulus of a well when said device is in operating position in said
well.
14. A device in accordance with claim 9 including conduit means
connected with said device communicating with a side of said piston
opposite said dome chamber for conducting control fluid under
pressure from a surface control system to said piston when said
device is in operating position in said well and said passage means
at said second end of said dome chamber communicates directly with
the tubing-casing annulus of said well when said device is in said
operating position in said well.
15. A safety valve for a well tubing string comprising: a tubular
outer housing member adapted to be operatively connected with said
tubing string, said housing member having a longitudinal flow
passage disposed coincident with the flow passage through said
tubing string when said valve is operatively connected with said
tubing string; a tubular valve operator longitudinally movably
mounted in said housing member; a valve in said housing member
operatively connected with said valve operator to be opened and
closed responsive to longitudinal movement of said valve operator
for controlling flow along said longitudinal passage of said
housing member; means in said housing member biasing said valve
operator longitudinally to close said valve comprising a chamber
for a fixed predetermined charge of gas under pressure acting upon
said valve operator; spring means between said housing member and
said valve operator to move said valve operator to close said valve
upon occurrence of a predetermined low pressure condition
communicated to said valve housing member, said pressure condition
opposing the forces of said spring and said charge of gaseous
pressure; and deactivating means between said valve operator and
said housing member for rendering inoperative said pressure
condition opposing the forces of said spring and said charge of
gaseous pressure whereby said opposing pressure condition is
ineffective to bias said valve open whereby said valve is closed
responsive to a predetermined high pressure condition communicated
to said valve.
16. A well valve in accordance with claim 15 wherein said means for
closing said valve responsive to said predetermined high pressure
include a pair of telescopically coengaged annular pistons between
said valve operator and said housing member, a first of said
annular pistons releasably engaging said valve operator for holding
said valve operator at a position at which said valve is open
responsive to control pressure communicated to said valve, said
first piston opposing the force of said spring means and said fixed
predetermined charge of gas, and said second annular piston being
engageable with said valve operator for releasing said valve
operator from said first annular piston to deactivate said first
piston and forcing said valve operator in a direction to close said
valve independently of said spring and said charge of gas
responsive to said predetermined high pressure.
17. A well valve in accordance with claim 15 wherein said
deactivating means for closing said valve responsive to said
predetermined high pressure comprises displaceable seal means
confining said charge of gas in said chamber and adapted to be
moved ina a non-sealing relation for equalizing the pressure in
said chamber with the pressure communicated to said valve from
exterior of said housing member to permit said spring to move said
valve operator to a position to close said valve.
18. A well valve in accordance with claim 17 wherein said
deactivating means for closing said valve responsive to said high
predetermined pressure includes an annular piston between said
valve operator and said housing member at one end of said chamber
for said charge of gas, said annular piston being responsive to
said pressure communicated to said valve from exterior of said
tubular housing and being movable from a first sealing relationship
between said housing member and said valve operator to a second
non-sealing relationship between said valve operator and said
housing member at which said chamber is communicated with said
pressure exterior of said housing member.
19. A flow control device for a well tubing string comprising: a
tubular housing adapted to be operatively connected with said
tubing string and having a longitudinal flow passage disposed
coincident with a flow passage through said tubing string when said
housing is so associated with said tubing string; a tubular valve
operator concentrically positioned within said housing for movement
between a valve-open position and a valve-closed position, said
valve operator having a longitudinal flow passage coincident with
said flow passage through said housing; valve means within said
housing movable between open and closed positions for controlling
fluid flow in said housing into said valve operator; said valve
operator being concentrically spaced within said housing; said
valve operator and said housing having means dividing the annular
space between said housing and said valve operator along the length
of said operator into a first upper annular chamber, a second
intermediate annular chamber, and a third lower annular chamber; a
seal between said housing and an upper end portion of said valve
operator sealing at a location between said upper chamber and said
flow passage through said housing; said housing having a port
communicating with said first upper annular chamber; said valve
operator having an annular piston dividing said upper and said
second intermediate annular chamber for biasing said operator
downwardly responsive to a fluid pressure communicated to said
first side port into said upper chamber and biasing said operator
upwardly responsive to pressure in said second chamber; side port
and port closure means in said housing into said second
intermediate chamber for injecting gas into said chamber to
pressurize said chamber to a predetermined value for biasing said
valve operator upwardly; a spring between said housing and said
valve operator biasing said valve operator upwardly; seal means
between said housing and said valve operator at the lower end of
said second chamber separating said second chamber from said third
chamber; said housing being provided with a second side port
communicating with said third lower annular chamber; seal means
between said valve operator and said housing below said second
lateral port sealing between said housing and said valve operator
at a location between said longitudinal passage through said
housing and said third lower annular chamber; and means between
said valve operator and said housing for effecting pressure
equalization across said annular piston on said valve operator for
closure of said valve responsive to a predetermined high pressure
around said tubular housing.
20. A valve for controlling flow through a tubing string of a well
comprising: a tubular housing having a longitudinal flow passage
therethrough and adapted to be operatively associated with said
tubing string, said flow passage being coincident with the flow
passage along said tubing string when said housing is so
associated; a tubular valve operator having a longitudinal flow
passage therethrough operatively associated in concentric
relationship within said housing, said flow passage of said
operator being coincident with said flow passage of said housing,
said operator being movable between valve-open and valve-closed
positions; a valve supported in said housing and operatively
connected with said valve operator for controlling flow through
said flow passages of said housing and said valve operator, said
valve being opened and closed by said valve operator; said valve
operator in said housing being concentrically arranged to define
therebetween a first upper annular chamber, a second intermediate
annular chamber, and a third lower annular chamber; seal means
between an upper end portion of said valve operator and said
housing above said first upper annular chamber sealing between said
valve operator and said housing at a location between said flow
passage through said housing and said first upper annular chamber;
means providing a side port and a closure member for said port in a
wall portion of said housing leading to said first upper annular
chamber whereby said chamber may be sealed at a pressure less than
the pressure in said second intermediate annular chamber; a seal
between said housing and said valve operator sealing between said
housing and said valve operator between said first and second
annular chambers; said housing having a lateral port leading to
said second annular chamber below said seal between said first and
second annular chambers; said operator having an annular piston
separating said second annular chamber and said third annular
chamber, said piston having a seal for sealing between said piston
and said housing; a stop shoulder provided within said third
annular chamber on said housing spaced below said operator piston;
a spring confined in said third annular chamber between said stop
shoulder and said annular piston on said valve operator for biasing
said valve operator in a direction to close said valve; said
housing having a side port and closure means leading to said third
annular chamber for charging said chamber with a gas to provide a
pressure therein of a predetermined value for applying a gas
pressure force to said operator piston for biasing said valve
operator in a direction to close said valve; an annular piston
disposed in said third annular chamber below said stop shoulder
therein, said piston having a head portion and a reduced skirt
portion; seal means sealing between said annular piston and said
valve operator and housing whereby the lower end portion of said
third annular chamber is sealed at a first position of said annular
piston and said seal means are moved with said piston into a larger
portion of said third annular chamber at a second position of said
annular piston for communicating said third annular chamber below
said piston with said chamber above said piston; said housing
having a lateral port communicating with said reduced portion of
said third annular chamber below said annular piston for applying a
pressure to said annular piston from exterior of said housing for
forcing said piston upwardly to permit communication past said
piston into said third annular chamber above said piston to permit
said valve to close under predetermined high pressure conditions
around said valve; and a seal within said housing around said valve
operator below said side port into said third annular chamber for
sealing between said housing and said valve operator at a location
between said third annular chamber and said longitudinal flow
passage through said housing, said latter seal engaging said valve
operator around a line of sealing engagement with said valve
operator of the same diameter as a line of sealing engagement
between said seal at the upper end of said first upper annular
chamber with said valve operator at the upper end thereof whereby
said valve operator is non-responsive to pressure conditions
through said longitudinal flow passage of said housing.
21. A valve for flow control through a tubing string of a well
comprising: a tubular valve housing adapted to be operatively
associated with said tubing string and having a longitudinal flow
passage coincident with a flow passage through said tubing string
when said housing is so associated; a tubular valve operator having
a longitudinal flow passage disposed for longitudinal movement
within said housing; a valve operatively connected in said housing
and coupled with said valve operator, said valve being opened and
closed by longitudinal movement of said valve operator; said valve
operator and said housing being concentrically spaced to define
upper and lower annular chambers therebetween; a seal between said
housing and an upper end portion of said valve operator at the
upper end of said upper chamber for sealing between said valve
operator and said housing at a location between said longitudinal
flow passage through said housing and said upper chamber; said
valve operator having an external annular operator piston dividing
said upper annular chamber said said lower annular chamber; said
housing having an internal stop flange along said lower annular
chamber spaced from said operator piston; a spring disposed within
said lower annular chamber between said operator piston and said
stop flange for biasing said valve operator in a direction to close
said valve; a lower portion of said lower annular chamber being
incrementally reduced in radial thickness by variations in wall
thickness of said valve operator and said housing along said lower
portion of said lower annular chamber; an annular relief piston
disposed within said lower portion of said lower annular chamber
and having seals around inner and outer wall portions of a head
portion thereof for sealing with said valve housing and said valve
operator to close said lower annular chamber along said lower
portion thereof for defining within said chamber between said
piston and said operator piston a dome chamber for containing a gas
under predetermined pressure for applying a force to said operator
piston to bias said valve operator in a direction to CLOSE SAID
VALVE: A SIDE PORT AND CLOSURE MEANS PROVIDED IN SAID HOUSING INTO
SAID LOWER ANNULAR CHAMBER ABOVE SAID annular piston for charging
said dome chamber to a predetermined gas pressure, said upper
annular chamber having a cross-sectional area less than the
cross-sectional area of said dome chamber for reducing the value of
the pressure to which said dome chamber is charged under
predetermined well conditions; said annular relief piston having a
lower reduced skirt portion extending into a reduced lower end
portion of said lower annular chamber; seal means within said lower
reduced portion of said lower annular chamber sealing within said
chamber portion below a lower end of said relief piston skirt
portion; said annular relief piston being movable upwardly from
lower reduced portions of said lower annular chamber to a position
out of sealing engagement between said valve operator and said
housing to communicate past said piston into the lower end of said
portion of said lower annular chamber defining said dome chamber;
said housing having a side port communicating with said lower end
portion of said lower annular chamber below said packing at the
lower end of said relief piston skirt portion for communication
with a pressure source exterior of said valve housing; and a seal
between said valve operator and said housing at the lower end of
said lower annular chamber below said port in said housing leading
to said chamber for sealing between said valve operator and said
housing at a location between the longitudinal flow passage through
said housing and the lower end of said lower annular chamber, said
latter seal effecting a seal between said operator and said housing
around a line of sealing engagement equal to a line of sealing
engagement between said operator at the upper end thereof in said
housing by said seal at the upper end of said upper first annular
chamber whereby said valve operator is nonresponsive to pressure
conditions within said longitudinal flow passage of said
housing.
22. A well flow control valve in accordance with claim 21 wherein
said valve operator and said valve housing are shaped along a
portion of the lower end portion of said lower annular chamber at a
first lower position of said annular piston to provide annular
space between the piston head of said relief piston and the sealed
lower reduced skirt portion of said piston, which space is sealed
during assembly of said valve at a pressure below the pressure in
said dome chamber during normal operation of said valve, and side
port and shear pin means disposed laterally through said valve
housing into said reduced skirt portion of said relief piston for
sealing said lower portion of said lower annular chamber along said
reduced piston skirt portion at a desired pressure and said shear
pin being adapted to hold said piston against upward movement until
a predetermined pressure is applied through said side port below
said skirt portion.
23. A valve for controlling fluid flow through a tubing string of a
well comprising: a tubular housing adapted to be operatively
associated with said tubing string and having a longitudinal flow
passage coincident with the flow passage through said tubing string
when so associated; a tubular valve operator concentrically
disposed within said valve housing and having a longitudinal flow
passage coincident with said flow passage of said housing and
longitudinally movable for opening and closing said valve; a valve
within said housing coupled with said valve operator and adapted to
be opened and closed responsive to longitudinal movement of said
valve operator; said valve operator being concentrically spaced
within said housing and said housing and said valve operator being
shaped to define upper, intermediate, and lower annular chambers
between said operator and said housing; a seal between said valve
operator along an upper end thereof and said housing at the upper
end of said first upper annular chamber for sealing between said
housing and said operator at a location between said first chamber
and said flow passage through said housing; a side port and closure
means in said housing opening to said first annular chamber for
sealing said chamber at a desired pressure; said operator having an
annular operator piston thereon and having seal means therein for
sealing between said piston and said housing separating said first
annular chamber and said second annular chamber, said second
annular chamber comprising a dome chamber adapted to be pressurized
to a predetermined level for providing a gas pressure within said
dome chamber for applying a force to said operator piston for
biasing said valve operator in a direction to close said valve;
said housing having an internal flange and seal means thereon
between said valve operator and said housing defining a lower end
of said dome chamber; a spring within said dome chamber confined
between said operator piston and said internal flange of said
housing for biasing said valve operator in a direction to close
said valve; said port means having closure means in said housing
opening into said dome chamber to permit said chamber to be
pressured with a gaseous medium to a desired level; said housing
having an internal flange and seal means engaging said valve
operator defining a lower end of said lower annular chamber between
said valve operator
and said housing; a pair of telescopically related annular pistons
slidably disposed in said lower annular chamber, each of said
pistons having a had portion and reduced skirt portion, the skirt
portions of said pistons being intermeshed in telescopic
relationship; said housing having a side port opening into said
lower annular chamber between said annular pistons, whereby said
annular pistons are urged in opposite directions responsive to
pressure communicated into said chamber through said side port;
said valve operator having an external annular operating flange
disposed in said lower annular chamber above said upper annular
piston whereby upward movement of said upper piston lifts said
valve operator to close said valve; shear means releasably securing
said upper piston with said valve housing at a first lower position
at which said valve operator is permitted to move longitudinally
between upper and lower end positions; shearable means releasably
coupling said lower piston with said valve operator whereby said
lower piston is adapted to hold said valve operator at a lower end
position for holding said valve open responsive to a pressure
applied from exterior of said housing through side port into said
lower annular chamber between said annular pistons when said
pressure is of a value sufficient to overcome the pressure in said
dome chamber and the force of said spring against said annular
operator piston; an internal annular flange in said housing
defining a lower end of said lower annular chamber and providing a
lower stop shoulder for said lower annular piston positioning said
piston at a lower end position for holding said valve operator at a
position at which said valve is open; and a seal in said flange at
the lower end of said lower annular chamber sealing between said
flange and said valve operator for sealing between said housing and
said valve operator at a location between said longitudinal flow
passage through said housing and a lower end of said lower annular
chamber, said seals in said lower housing flange and at the end of
said upper annular chamber sealing along lines of engagement with
said valve operator of equal diameter whereby said valve operator
is non-responsive to pressure conditions in said longitudinal flow
passage through said housing.
24. A device for controlling flow in a flow conductor comprising: a
valve housing having a longitudinal bore defining a flow passage
therethrough; valve means supported in said housing adapted to be
opened and closed to control fluid flow through said housing; valve
operator means movable longitudinally in said housing and
operatively connected with said valve means for opening and closing
said valve means; said valve operator means having a flow passage
communicating with said flow passage through said housing; means
applying a force to said valve operator means to bias said valve
operator means in a direction to close said valve means;
pressure-responsive actuating means having an operative connection
with said valve operator means for biasing said valve operator
means in a direction to open said valve means when a pressure is
applied to said actuating means; means for conducting a control
pressure fluid to said pressure-responsive actuating means to apply
said pressure to said actuating means and thereby hold said valve
means in open position; and means operatively connected with said
operator means and also responsive to the pressure being applied to
said actuating means for deactivating said pressure-responsive
actuating means for effecting closure of said valve means when said
applied pressure exceeds a predetermined value.
25. A device as set forth in claim 24, wherein: the means for
conducting pressure to said pressure-responsive actuating means is
at least one lateral port extending through the wall of the valve
housing.
26. A device for controlling flow in a flow conductor comprising: a
valve housing having a longitudinal bore therethrough; valve means
supported in said housing adapted to be opened and closed to
control fluid flow through said housing; valve operator means
movable longitudinally in said housing and operatively connected
with said valve means for opening and closing said valve means;
said valve operator means having a flow passage communicating with
said flow passage through said housing; means applying a force to
said valve operator means to bias said valve operator means in a
direction to close said valve means; pressure-responsive actuating
means having an operative connection with said valve operator means
for biasing said valve operator means in a direction to open said
valve means when control pressure is applied to said actuating
means; means for conducting control pressure to said
pressure-responsive actuating means; means for confining the
pressure applied to said actuating means in a manner to assure that
said pressure is applied to said means in a direction holding the
valve means open, said confining means displaceable to a non
pressure confining relationship for effecting an equalization of
pressure across the pressure-responsive actuating means to effect
closing of said valve means when said pressure confining means is
subjected to a control pressure above a predetermined value.
27. A device as set forth in claim 26, wherein: said confining
means is at least one sealing means rendered inoperative responsive
to said control pressure above a predetermined value and positioned
with respect to the pressure-responsive actuating means to effect
an equalization of pressure across the actuating means when said
sealing means is rendered inoperative.
Description
This invention relates to well tools and more particularly relates
to safety valves for wells.
In both the drilling and production of oil wells, operating
conditions and equipment malfunctions frequently develop which
require that fluid flow be quickly shut off through well structure
such as production and drill string tubings. In the drilling of
wells, it may be desirable to be able to maintain a closed flow
passage through a drill string while providing a capability of
opening the drill string when certain well tests are to be
performed. Alternatively, it may be desired to hold such a valve
open and close it when needed. In the drilling of subsea wells,
conditions such as storms often make it necessary to shut in a well
and temporarily abandon it until sea conditions permit reentry. In
such wells, a valve in the drill string may be held open during
drilling and thereafter closed while the drill string is left
supported in the well by means of special well head apparatus. In
the production of subsea wells by secondary means, such as gas
lift, and by primary recovery methods involving flow in response to
normal formation pressures a well must be protected against the
invasion of sea water in the event of a structural failure of the
well equipment by a tubing safety valve.
Tubing string valves for use both in producing wells and when
drilling wells are well known. Some such valves often are
controlled responsive to the tubing casing annulus pressure or the
pressure of a control fluid conducted to the valve through a
special control line from the surface. Such valves currently
available may be operated responsive to a predetermined low
pressure while other such valves are responsive to predetermined
high pressure levels. Generally, however, the valves are not
adapted to react to both a predetermined low and a predetermined
high pressure. Additionally, such valves often are not constructed
to close when certain valve malfunctions occur. For example, in
certain safety valves which include a dome chamber, leaks may occur
between the dome chamber and the tubing in which the valve is
installed without the valve responding by closing because of the
failure of such leak to have any effect upon the tubing-casing
annulus pressure. In other available safety valves the casing
annulus pressure may rise to a value of sufficient magnitude to
effect collapse of the tubing without closing the safety valve.
It is a particularly important object of the invention to provide a
new and improved well tool.
It is another especially important object of the invention to
provide a new and improved well safety valve useful in both the
drilling and the production of wells.
It is another object of the invention to provide a well safety
valve which is closable responsive to a predetermined low
tubing-casing annulus pressure.
It is another object of the invention to provide a well safety
valve which is closable responsive to a predetermined high
tubing-casing annulus pressure.
It is another object of the invention to provide a well safety
valve which may be included in the drill string used in drilling a
well for making drill stem tests on the well during the process of
drilling to determine the presence and character of formation
fluids.
It is another object of the invention to provide a well safety
valve which may be included in the drill string used in drilling a
well for shutting in subsea wells during conditions such as storms
when the wells must be temporarily abandoned.
It is another object of the invention to provide a well safety
valve which is especially useful in the production of subsea wells
both by primary and secondary means such as gas lifts to protect
the wells against equipment failure causing invasion by sea
water.
It is another object of the invention to provide a tubing safety
valve responsive to tubing-casing annulus pressure increases to
avert tubing damage or collapse effected by well system failures
such as tubing leakage at a location which applies tubing pressure
to the hydrostatic pressure of liquids in the annulus whereby
annulus pressures may build to a value sufficient to collapse the
tubing.
It is another object of the invention to provide a well safety
valve which closes responsive to a valve malfunction such as a seal
failure between the casing and the tubing and between the casing
and the dome chamber.
It is another object of the invention to provide a tubing safety
valve which may be closed by an increase in casing pressure where a
valve malfunction prevents closure by a normal decrease in the
annulus pressure.
It is another object of the invention to provide a well safety
valve having a dome chamber which functions at a pressure which is
chargeable under field conditions from commercially available
compressed gas.
It is another object of the invention to provide a well safety
valve which is operable by either casing annulus pressure or
pressure communicated to the valve through a control line from the
surface.
It is another object of the invention to provide a well safety
valve having a valve operator biased toward a closed position by
dome pressure and a spring and including casing pressure responsive
chambers at each end of the valve operator whereby the dome is
equalized with the annulus by a seal failure at either end of the
dome and the spring closes the valve.
It is another object of the invention to provide well safety valves
of the character described wherein valve operating characteristics
may be varied by altering the relative sizes or proportions of
various pressure responsive elements of the valves.
It is another object of the invention to provide well safety valves
of the character described which include sealed chambers adapted to
be charged to desired predetermined pressures during valve assembly
and preparation.
It is another object of the invention to provide well valves which
are operable independently of the tubing-casing annulus pressure to
protect such valves against possible debris in the annulus.
It is another object of the invention to provide well safety valves
of the character described having control apparatus in which valve
operating pressures are communicated to a control piston and to
pressure displaceable seals through a control line from the surface
extending to the valve independently of the tubing-casing annulus
whereby the valve apparatus holds the valve open at a control
pressure within a predetermined range and effects valve closure
responsive to a control fluid pressure below or in excess of a
predetermined value.
It is another object of the invention to provide well safety valves
of the character described wherein a control fluid pressure is
communicated to an operating piston at one end of a dome chamber
through a control line extending to the valve from the surface
independently of the tubing-casing annulus and the other end of the
dome chamber is closed by a pressure displaceable seal exposed to
the tubing-casing annulus pressure for effecting valve closure in
response to a high casing pressure.
In accordance with the invention there is provided a well safety
valve for use in a tubing string which includes a valve member
which may be a ball valve, a poppet valve, or a flapper valve
coupled with a tubular valve operator having an external annulur
piston formed thereon, a valve housing concentrically disposed
around the valve and operator member and defining a dome chamber
around the operator enclosing the annular piston. A spring is
disposed within the dome chamber confined between a flange in the
housing and a flange on the operator biasing the valve closed. The
dome chamber is adapted to be pressured to a desired value to
provide an additional force biasing the valve closed. In one
embodiment of the valve an annular chamber communicating with the
casing is provided at opposite ends of the dome chamber so that
leakage of seals at either end of the dome chamber causes the dome
chamber to reach casing annulus pressure allowing spring valve
closure. In a second embodiment of the valve an additional annular
chamber at atmospheric pressure is provided between the valve
operator and the valve housing at the upper end of the valve for
reducing the dome pressure required. In the second and a third
embodiment of the valve a lower annular piston is disposed around
the valve operator within the valve housing movable responsive to
casing pressure to permit the valve to close at a predetermined
high casing pressure. In a fourth embodiment of the valve an
annular atmospheric chamber is provided at the upper end of the
valve to reduce the required dome pressure and a pair of
telescopically disposed annular pistons are positioned in an
annular chamber between the valve operator and the valve housing
below the dome chamber for forcing the valve closed responsive to a
predetermined high casing pressure. Each of the several embodiments
of the valve is provided with a threaded fitting at each end for
connecting the valve in either a drilling string or a production
tubing string whereby the valve comprises an integral part of the
string. In another embodiment of the valves control fluid pressure
is communicated through a single control line to a control piston
at one end of a dome chamber and to a displaceable seal at the
other end of the dome chamber. In a further embodiment of the
valves, control fluid is communicated through a control line to the
control piston at one end of the dome chamber and a pressure
displaceable seal at the other end of the dome chamber is exposed
to the tubing-casing annulus pressure.
In the various embodiments described and claimed the several seals
used to close the dome chamber and properly otherwise confine the
various pressures involved serve functions including assuring that
the control pressures used to hold the valve open are directed to
the proper side of the annular piston or pressure responsive means
on the valve operator. Such confining means may include seals which
are displaced to non-sealing relation by predetermined high
pressures as may be applied by a control fluid pressure or a
pressure admitted by a tubing rupture. The terms "control fluid" or
"control fluid pressure" shall include both fluid pressures
directed to a valve for the specific purposes of holding the valve
open, of closing the valve, and fluids which enter a ruptured
tubing such as sea water in an offshore well. The sea water, for
example, serves a control fluid function by emergency closing of
the valve to shut-in the well.
The various forms of the invention and the foregoing objects and
advantages will be apparent from reading the following detailed
description taken in conjunction with the accompanying drawings
wherein:
FIG. 1 is a longitudinal view in section and elevation of a first
embodiment of a valve made in accordance with the invention showing
the valve open;
FIG. 2 is a longitudinal view in section and elevation of the valve
of FIG. 1 closed;
FIG. 3 is a fragmentary view in section of a poppet type valve
which may be employed with the valve operating structure;
FIG. 4 is a fragmentary view in section of a flapper type valve
which may be employed with the valve operator structure;
FIG. 5 is a fragmentary view in section showing a second form of
valve operator structure in accordance with the invention;
FIG. 6 is a fragmentary view in section illustrating a third form
of valve operator structure embodying the invention;
FIG. 7 is a fragmentary view in section illustrating a fourth form
of valve operator structure embodying the invention, showing the
valve open;
FIG. 8 is a fragmentary view in section showing the valve of FIG. 7
closed;
FIG. 9 is a fragmentary view in section illustrating an alternate
form of the lower end of the valve structure as shown in FIG.
5;
FIG. 10 is a fragmentary view in section showing an alternate form
of the valve operating structure of the valve operating system
shown in FIG. 1; and
FIG. 11 is a fragmentary view in section of another alternate form
of the valve operating system of FIG. 1.
Referring particularly to FIGS. 1 and 2 of the drawings a safety
valve 20 embodying the invention is illustrated for use as an
integral part of a tubing string, not shown, which may be either a
production string used in either primary or secondary well
production or may be a drilling string employed in the drilling of
a well. For a better understanding of the valve and one of its
applications in a gas lift system of a well, reference may be had
to U.S. Letters Pat. No. 3,642,070 issued Feb. 15, 1972, to Frank
H. Taylor and Warner M. Kelley. The valve 20 may be substituted in
the tubing string 34 of the reference patent for the landing nipple
41 whereby the valve is disposed in the tubing string below the gas
lift valve and functions responsive to the pressure applied in the
annulus 45 between the casing and the tubing string. The valve 20
is connected in the tubing string by upper and lower tubing
couplings 21 and 22 which are threaded, respectively, on upper and
lower threaded reduced valve housing portions 23 and 24 of a
tubular valve housing 25. A tubular valve operator 30 is movably
disposed in concentric relationship within the housing 25 for
opening and closing the valve. A ball valve 31 is rotatably secured
between the lower end of the valve operator and a tubular lower
valve seat 32 biased upwardly by a spring 33. As discussed in
detail hereinafter, the ball valve 31 is rotatable between the open
position of FIG. 1 and the closed position of FIG. 2 by the
operator 30 responsive to a number of different well conditions and
valve malfunctions for shutting off flow through the valve for both
safety and other reasons.
The bore of the housing 25 is enlarged along an upper end portion
35 defining a downwardly facing internal annular stop shoulder 40
at the upper end of the housing where the housing connects with the
threaded end section 23. The bore of the housing 25 is still
further enlarged along a section 41 which is concentrically spaced
from the valve operator 30. A ring seal 42 is disposed in an
internal annular recess 43 sealing between the upper end portion of
the housing and the upper end portion of the valve operator. An
annular piston 44 is formed on the valve operator including an
upper external annular retainer flange 45. A ring seal 50 is held
on the piston portion against the flange 45 by a retainer ring 51
secured to the piston by a shear pin 52. The piston of the valve
operator separates the annular space between the housing wall
section 41 and the valve operator into an annular dome chamber 53
below the piston portion and an annular casing pressure chamber 54
above the piston. A port 54a in the housing wall opens to the
chamber 54 to apply casing pressure above the piston. A coil spring
55 is disposed in the dome chamber between a retainer ring 60
seated against a downwardly facing stop shoulder 61 on the lower
end of the valve operator piston 44 and an internal annular flange
62 providing an upwardly facing internal annular stop shoulder 63
in the housing wall. The valve housing is reduced in internal
diameter along an intermediate portion 64 which is spaced from the
valve operator defining an annular recess 65 at the lower end of
the dome chamber. The lower end of the recess 65 is defined by an
internal annular stop shoulder 70 which supports a ring seal 71
held in place by retainer ring 72 secured to the housing wall
portion 64 by a shear pin 73. The ring seals 50 and 71 seal the
upper and lower ends of the dome chamber 53 which is filled with a
suitable gas under pressure through a side port 74 provided in the
wall section 41 of the valve housing and sealed by a plug 75. The
forces of the gas in the dome chamber and the spring 55 bias the
valve operator 30 upwardly toward a valve-closed position.
The valve housing section 64 is provided with a side port 76 which
communicates with an internal annular recess 77 within the valve
housing around the valve operator below the internal housing
shoulder 70. Below the recess 75 a ring seal 80 is positioned
around the valve operator within an internal recess 81 of the valve
housing to seal between the housing and the valve operator below
the recess 75.
At the lower end of the valve housing portion 64 the bore of the
housing is enlarged below a downwardly and outwardly sloping stop
shoulder 82 and extends at a uniform diameter along a wall portion
83 of the housing to a reduced diameter housing portion 84 defining
an upwardly facing stop shoulder 85. The valve operator has an
external annular tapered flange 90 above the ball 31 which is
engageable, as seen in FIG. 2, with the housing shoulder 82
defining the upper limit of movement of the valve operator at which
the ball valve is closed. The lower end portion of the valve
operator is provided with an external annular recess 91 which
receives a pair of T-shaped ball valve hanger brackets 92 connected
between the ball valve 31 and the valve operator 30. The hanger
brackets 92 each has an inwardly projecting pin 93 engaging a
circular recess, not shown, in the ball valve 31. The brackets are
positioned on opposite sides of the valve operator so that the pins
93 engage diametrically opposed recesses of the ball valve
rotatably hanging the ball valve from the hanger brackets on an
axis of rotation perpendicular to the longitudinal axis of the
valve operator 30. Diametrically opposed, inwardly projecting pins
94 are secured within the valve housing wall section 83 extending
into slots, not shown, on opposite sides of the ball valve so that
as the ball valve is raised and lowered by the hanger brackets with
the valve operator the co-action of the pins in the slots of the
ball valve causes the ball valve to rotate. Further structural
details of the ball valve operating mechanism may be found in U.S.
Pat. No. 3,273,588 issued to W. W. Dollison Sept. 20, 1966, and
U.S. Pat. 3,292,706 issued to George C. Grimmer and Leonard
McCasland Dec. 20, 1966. The lower end of the valve operator 30 is
provided with a spherical upper valve seat surface 95 with which
the ball valve engages in fluid-sealed relationship when the valve
is at the closed position of FIG. 2. A relief port 96 is provided
in the operator 30 above the seat 95 to prevent a pressure build up
along the operator as the seat 90 engages the seat 82 and a suction
effect when the seats separate as the operator moves downwardly to
open the valve. The ball valve has a bore 100 of substantially the
same diameter as the bore through the valve operator and the valve
seat.
The lower valve seat 32 is a tubular member having an upper
external annular flange 101 for engagement of the upper end of the
coil spring 33, which is confined between the housing flange 85 and
the flange 101, biasing the valve seat upwardly against the ball
valve. The upper end of the lower valve seat is provided with an
internal spherical seat surface 103 which engages the ball
valve.
In operation the valve 20 may be used in a number of different
types of well systems for drilling and in production such as gas
lift systems. The valve may be responsive to the tubing casing
annulus pressure, or a control line may be connected into the port
54a from a fluid pressure control system at the surface which
senses various operating conditions in response to which the valve
is closed. For example, a control line may be connected at the
surface with an OTIS SURFACE CONTROL MANIFOLD shown and described
at page 3,887 of the 1970-1971 edition of the Composite Catalog of
Oil Field Equipment and Services. Systems of the nature of FIG. 1
using a separate control line are discussed hereinafter in
connection with FIGS. 10 and 11. The valve operation of the FIG. 1
valve system will be described in terms of its functioning
responsive to the tubing-casing annulus pressure which can
constitute lift gas in a gas lift system, drilling fluid in a well
drilling system, or control fluid in a production system where the
annulus serves basically the function of a control fluid flow
passage. The spring 55 and the pressure in the dome chamber 53 are
selected to support the valve operator 30 at an upper end position
to hold the ball valve 31 closed, as seen in FIG. 2, during
below-normal tubing-casing annulus pressure. The force of the
spring and the dome pressure exerted on the piston 44 apply an
upward force to the valve operator which is opposed by the annulus
pressure communicated through the port 54a into the chamber 54
applying a downward force to the piston 44 of sufficient magnitude
to hold the operator downwardly against the spring and dome
pressure for maintaining the ball valve in the open position as in
FIG. 1 during normal tubing-casing annulus pressure.
If the annulus pressure is reduced, as by leakage, or by positive
action of the control system where the annulus fluid is control
fluid, the downward force on the piston 44 in the chamber 54 is
reduced permitting the force of the spring and the dome pressure to
lift the piston 44 and the operator 30 rotating the ball valve 31
to the closed position of FIG. 2. The operator moves upwardly until
the seat 90 on the operator engages the stop shoulder 82 within the
valve housing. As the ball valve moves upwardly, it is followed by
the upwardly biased lower valve seat 32. Any pressure differential
in the tubing upwardly across the ball valve urges the ball valve
into a sealed relationship with the operator valve seat 95.
An increase in pressure in the annulus communicated through the
port 54a to the chamber 54, when it exceeds a predetermined value
sufficient to overcome the dome pressure and spring 55 acting
against the piston 44, forces the valve operator 30 downwardly,
returning it to the position of FIG. 1 rotating the valve 31 back
to the open position.
In accordance with the special features and benefits of the
invention, the valve 20 is adapted to close responsive to a number
of different valve malfunctions and well system operating condition
changes which might endanger such portions of a well system as the
tubing string. A leak in the ring seal 43 tends to equalize the
pressures in the bore of the valve and the annulus, and when the
differential reaches a value below the level required to hold the
valve open against the spring and dome pressure, the valve closes.
A leak at the ring seal 50 of the operator piston 44 of the valve
equalizes the pressures in the dome chamber and the annulus so that
the higher annulus pressure is no longer available to hold the
valve open and, therefore, the valve operator is moved upwardly by
the spring 55 closing the valve. Similarly, a leak at the lower
ring seal 71 communicates the dome chamber with the annulus 77
leading to the side port 76 equalizing the pressures in the dome
and the annulus so that the spring closes the valve. This
particular feature at the lower end of the dome chamber is a
distinguishing feature of the present valve as compared with
presently available safety valves of a similar type. Generally,
available valves use a seal at the lower end of the dome chamber
which seals between the dome chamber and the tubing so that a leak
in the seal would not necessarily effect valve closure but might in
fact create a greater pressure differential across the operator
piston as the tubing pressure may be below annulus pressure.
Another seal which may leak in the valve 20 is the ring seal 80
which communicates the tubing through the annular space 77 and the
port 76 with the annulus so that the tubing and annulus pressures
become equalized whereby the annulus pressure is reduced to a
sufficient level for the dome pressure and spring to close the
valve. Thus, leakage of any one of the seals at the opposite ends
of the dome chamber and between the valve operator and the valve
housing establishes pressure conditions which effect closure of the
valve. close said valve; a side port and closure means provided in
said housing into said lower annular chamber above said forces the
ring seal at either or both ends of the dome chamber out of sealing
relationship to equalize the annulus and dome pressures. Such a
high pressure may force the ring seal 50 against the retainer ring
51 shearing the pin 52 to permit the retainer ring and the ring
seal to be forced into the upper end of the dome chamber so that
the seal is displaced from a sealing relationship allowing
equalization of the annulus and dome pressures. Similarly, the
lower ring seal 71 may be forced upwardly against the retainer ring
72 shearing the pin 73 moving the ring seal out of sealing
relationship to equalize the annulus and dome chamber pressure at
the lower end of the dome chamber. In either situation, the
equalization of annulus and dome pressures permits the spring 55 to
lift the valve operator, closing it. This, of course, is a safety
feature of the valve which would not be employed during normal
operations but is available for emergency closing which might be
brought about by a number of situations such as a tubing leak which
would apply an excessively large pressure into the casing annulus,
or, if some other condition developed where an emergency exists
causing an excessively high annulus pressure, the valve is closed.
It will be apparent that this technique of closing the valve
renders the valve inoperative for future normal use due to the
effective rupturing of the dome chamber by the displacement of
either or both of the seals at the opposite ends of the chamber
from their normal positions. The valve would, of course, have to be
retrieved from the well and repaired by replacement of the ring
seals and shear pins.
It will be apparent that changes in pressure in the tubing string
have no effect on the operation of the valve as the effective
sealed areas of the valve operator facing both upwardly and
downwardly are equal as defined by the ring seals 43 and 81 between
the operator and the valve housing. Thus, the only forces which may
affect operation of the valve are annulus pressures and changes in
pressures between the annulus and the dome chamber.
The valve 20 can be particularly useful during the process of
drilling, especially a subsea well, in at least two circumstances.
When drilling such a well, it may be necessary to abandon the well
during storm conditions. U.S. Pat. No. 3,411,576 issued Nov. 19,
1968, to Donald F. Taylor, Jr. shows a subsea well head which
permits temporary abandonment of a drilling well by hanging the
drill string in the well and removing certain surface equipment
until well re-entry is desired. A valve in accordance with the
present invention may be included in the drill string with the
valve being allowed to close while the well is temporarily
abandoned to shut in the well along the drill string itself. When
re-entry is desired, the casing annulus may be pressured up to open
the valve. In other uses, both in offshore and in conventional land
based wells, the valve may be included in the drill string at a
time when a drill stem test is desired. The drill string is run
into the well with the valve closed. Obviously, in such a drill
string the tubing may be dry above the closed valve. At a time when
a test of the formation fluids is desired, the casing annulus
around the drill string is pressured up from the surface to a
sufficient value to overcome the spring and dome pressure for
opening the valve. When the valve opens, the dry drill string above
the valve causes the well to come in and flow without the necessity
of swabbing the well. In primary production and in secondary
recovery wells located in subsea areas, the possible invasion by
sea water presents a continuing hazard. In a gas lift well a leak
in the casing will permit sea water to invade the casing, pass
through the gas lift valves, and through the string into the
formation. A valve constructed in accordance with the present
invention would be caused to close by the additional excessive
pressure of the sea water, causing a rupture of the shear pins
holding the seals in place at the opposite ends of the dome
chamber, releasing the pressure of the dome chamber to permit the
valve to close. In primary production wells the same events may
occur due to the invasion of sea water into the casing.
The principal components of the valve 20 which control operation of
the valve may be readily used with poppet and flapper type valve
members as represented by FIGS. 3 and 4. In view of the fact that
the operating mechanism of the valves represented in FIGS. 3 and 4
is identical to that of the valve 20, only the lower end portions
of such valves are shown to clearly identify them as poppet and
flapper type valves. Referring to FIG. 3, the poppet type safety
valve is represented by the reference numeral 20A. All of the
operating structure of the valve 20A is identical to the operating
structure of the valve 20 above and including the ring seal 80
sealing between the operator and the valve housing. The lower end
of a valve operator 30A is threaded into an enlarged upper end
portion of a tubular extension member 110. The valve operator 30A
is identical to the valve operator 30 along that major portion of
the operator 30 above the bleed port 96. Similarly, it may be
considered that the valve housing 25a is identical to the valve
housing 25 above the wall portion 83 of the housing 25. The
connector 110 has a downwardly and inwardly sloping seat surface
111 which is engageable with a seat or shoulder surface 112 within
a housing coupling 113. The engagement of the surface 111 on the
operator member extension 110 against the seat surface 112 of the
housing member limits the downward movement of the valve operator
in the housing. The operator extension 110 is threaded into a
poppet valve 114 which has side ports 115 admitting flow from below
the valve into the central bore of the valve through the operator
30A. The valve 114 has a seat surface 120 which engages a
downwardly and outwardly sloping seat surface 121 of the housing
member 113 when the valve 114 is at an upper closed position. In
FIG. 3 the valve 114 is shown at a lower end position at which the
seat surface 120 is spaced below the housing seat surface 121
permitting fluid flow through the ports 115. A tubular plug 122 is
threaded on the lower end of the housing member 113 around the
valve 114. The operation of the poppet valve 20A is identical in
all respects to the operation of the valve 20, the valve 114 being
raised and lowered between open and closed positions by the valve
operator 30A which is moved responsive to the various changes in
pressure conditions and the spring 55 as previously described with
respect to valve 20.
FIG. 4 shows a flapper type valve 20B which utilizes all of the
operating structure of the valve 20 substituting a flapper valve
130 for the ball valve 31. Above the ring seal 80 all of the
structure of the valve 20B is identical to the structure of the
valve 20. The lower end portion of the valve operator 30B is
enlarged providing a downwardly facing valve seat 131 which is
engageable by a seat surface 132 on the flapper valve 130 for
closing the valve. The valve 130 is mounted on an arm 133 secured
on a pin 134 for movement between the horizontal upper closed
position of FIG. 4 and a downwardly extending vertical open
position, not shown, to which the valve is pivoted from the valve
seat 131. A valve operating lug 135 having a shoulder surface 140
is engageable with a valve trip shoulder 141 on the valve operator
30B. When the casing annulus pressure forces the valve operator
piston 44 downwardly, the flapper valve is pivoted on the pin 134
to a vertical position into a side recess 142 formed in the valve
housing 25B. When pressure conditions return the valve operator
back upwardly, the trip shoulder 141 engages the lug face 140,
swinging the flapper valve upwardly. Upward flow into the valve
completes the movement of the flapper valve to the closed position
shown in FIG. 4. A plug 143 is threaded into the lower end of the
valve housing 25b. The operating structure and details of the
flapper valve assembly are essentially identical to those of U.S.
Pat. 3,071,151 issued Jan. 1, 1963, to Phillip S. Sizer. The manner
of operation and the conditions under which the valve 20B is
operated are identical to those described in relation to the safety
valve 20.
Under well conditions where debris is present in the casing which
might interfere with the valve operation and which, preferably, is
to be excluded from the valve at all times, an alternate form of
valve operating apparatus 20F as shown in FIG. 10 may be used. The
valve operating mechanism of the valve 20F is identical to that of
the valve 20 shown in FIG. 1, and thus all of the common components
are identified by the same reference numerals as used in FIG. 1. A
small flow conductor or control line 86 extends from a control
manifold 87 at the surface. The manifold 87 may be the previously
discussed Otis Surface Control Manifold which supplies a fluid
under controlled pressure condition to operate various downhole
tools such as the present valves. The control line 86 extends
downwardly in the tubing-casing annulus of the well in which the
valve is installed supported alongside the tubing string in any
suitable manner. At the valve 20F the control line 86 connects into
a fitting 88 having a side port 88a which communicates with the
valve housing side port 54a so that control fluid from the manifold
87 is communicated through the control line into the chamber 54 for
biasing the annular piston on the valve operator downwardly to hold
the valve at an open position. A short section 86a of the control
line extends downwardly from the fitting 88 to another side fitting
89 secured on the valve housing and provided with a port 89a
communicating with the valve housing side port 76 so that the
control fluid pressure from the manifold is also communicated
inwardly around the valve operator between the seals 71 and 80
above and below the port 76.
The operation of the valve 20F is identical to the operation of the
valve 20 other than the fact that the valve 20F is controlled by
fluid communicated through the control line 86 as distinguished
from fluid being communicated to the valve through the
tubing-casing annulus. In the event of a failure of the seal 50,
the pressure as communicated to the valve through the control line
is equalized between the dome chamber 53 and the chamber 54
permitting the spring 55 to lift the valve operator 30 to close the
valve. Similarly, a failure at the lower end of the valve at the
seal 71, also equalizes the pressure across the piston so that
control line pressure exists in the dome chamber as communicated
through the side port 76 past the seal 71 and in the chamber 54
which permits the spring to lift the valve operator to close the
valve. The pressure may be increased in the control line to a value
sufficient to shear either or both of the pins 52 and 73 allowing
the seals 50 and 71 to be displaced so that the pressure is
equalized across the piston between the chambers 54 and 53 allowing
the valve to be closed by the spring. This safety feature of the
valve is, of course, also operative in the event of destruction of
the control line and an increase in the tubing-casing annulus
pressure for any reason above the level required to displace the
seals.
A still further form of valve control apparatus is illustrated in
the valve 20G of FIG. 11 which utilizes a valve control system
identical to that of the valves of FIGS. 1 and 10. More
specifically, the valve 20G is identical to the valve 20 of FIG. 1
except that control fluid pressure is communicated to the valve
through the line 86 into only the upper side port 54a. As seen in
FIG. 11, the control line 86 extends from the surface control
manifold 87 to the side fitting 89 connected on the valve housing.
The side port 89a of the fitting is in communication with the valve
side port 54a so that control fluid from the manifold communicates
into the chamber 54 for biasing the valve operator piston
downwardly to hold the valve open. The side port 76 is in
communication with the tubing-casing annulus at all times. Thus,
the valve 20G remains sensitive to the casing pressure exterior of
the safety valve so that an excessive casing pressure will shear
the pin 73 to effectively deactivate the dome chamber. The form of
the valve 20G presents a limitation which is not inherent in the
valve 20 which communicates through both the side ports 76 and 54a
with the tubing-casing annulus. In the valve 20G the control fluid
pressure in the line 86 from the manifold may somewhat exceed the
normal casing pressure but must never exceed the casing pressure
sufficiently to produce a condition under which the pressure in the
chamber 54 above the operating piston would remain in excess of the
casing pressure and the spring force to hold the operating piston
downwardly and the valve open even if the lower seal 71 failed.
It will be recognized in connection with the configuration of the
valve shown in FIGS. 5 and 6 that the variations of the valve
structure as illustrated in FIGS. 10 and 11 may also be used with
operation of such valves being affected in the same manner as
described in connection with the valves 20F and 20G.
FIGS. 5-8 illustrate modified forms of safety valve operating
mechanisms which may be employed with ball, poppet, or flapper type
valves. The structure of the valve housing for these embodiments
above and below that shown in the drawings is identical to the
valve housing structure shown in FIG. 1.
Referring to FIG. 5, a well safety valve 20C has a tubular valve
operator 150 which is longitudinally movable within a valve housing
151 having opposite end portions connectible into a tubing string,
as seen in FIG. 1. The valve operator has a thin-walled upper end
portion 152 slidable in a bore portion 153 of the housing. A ring
seal 154 in an internal recess 155 of the housing seals between the
housing and the operator upper end portion 152. A bore portion 160
of the housing provides an annular space 161 within the housing
around the operator upper end portion 152. The housing has a port
162 closed by a removable plug 163 opening into the chamber 161.
During assembly of the valve, the chamber 161 is sealed at
atmospheric pressure. The wall thickness of the valve operator is
increased along a portion 164 the outer surface of which is spaced
from the bore wall surface of a valve housing portion 165 defining
an annular chamber 170 which communicates with the casing annulus
through a side port 171. A V-packing assembly 172 is disposed in
the annular space 170 above the port 171 between the housing and
the valve operator against an internal housing flange 173. The
outside diameter of the operator wall portion 164 is substantially
greater than the diameter of the operator wall portion 152 so that
the difference in the sealed areas of the valve operator defined by
the seal 172 and by the seal 154 provides a substantial annular
area of the valve operator which is exposed to the atmospheric
pressure in the annular chamber 161, which, in effect, reduces the
amount of force which must be supplied by a spring and the pressure
in the dome chamber of the valve when the valve is at operating
depth within a well.
The valve operator 150 of the valve 20C is enlarged along a piston
portion 174 which is sealed with the wall section 165 of the valve
housing by a ring seal 175 in an external recess 180 of the piston.
The piston 174 defines the upper end of a dome chamber 181
comprising the annular space between the valve housing and the
valve operator below the piston 174. The valve housing has an
internal annular flange 182 spaced from the wall portion of the
valve operator below the piston and supporting the lower end of a
valve operator spring 183. The upper end of the spring engages a
downwardly facing annular shoulder 184 on the lower end of the
piston 174. The spring biases the valve operator upwardly. The dome
chamber 181 is charged through a port 185 closed by removable plug
190. Due to the presence of the atmospheric chamber 161 above the
seal 172, it is not necessary to charge the dome chamber to as high
a pressure as would be required under the same operating conditions
in a well for a safety valve such as the valve 20. A substantial
portion of the valve operator is working against atmospheric
pressure in the chamber 161 while another portion of the operator
above the piston 174 is subjected to the casing annulus pressure in
the chamber 170 through the port 171. Thus, in a valve which may be
used deep in a well under high operating pressures, a dome chamber
pressure still may be used of a value which permits it to be
charged from available facilities, such as bottled gas in the
field.
The valve housing 151 of the valve 20C is increased slightly in
internal diameter along a wall portion 191 defining a slightly
larger lower end portion 192 of the dome chamber. The valve housing
is reduced slightly in internal diameter along a wall portion 193
and still further reduced in diameter along a wall portion 194
defining an upwardly facing shoulder surface 195. The valve housing
is still further reduced in internal diameter along a wall portion
200. An annular piston 201 having a lower akirt portion 202 is
disposed for movement between the valve housing and the operator
member at the lower end of the dome chamber. The piston has
internal and external ring seals 203 and 204, respectively, sealing
between the piston and the operator member and housing along the
housing wall portion 193. The space along the piston skirt portion
202 at the valve housing wall portion 194 defines an annular
chamber 205 which is at atmospheric pressure so long as the piston
is in the lower end position shown in FIG. 5 inasmuch as the valve
is assembled under atmospheric pressure when the piston is put in
place in the housing around the valve operator. A ring seal 210 in
a recess of the valve housing below the annular space 205 seals
between the housing and the piston skirt portion 202. An annular
space 212 between the valve operator and the valve housing wall
portion 200 is communicated with the casing annulus through a side
port 213 in the valve housing. Below the port 213 the valve housing
is reduced in diameter along a wall section 214 provided with an
internal recess 215 in which a ring seal 220 is disposed around the
valve operator. The seal 220 corresponds functionally with the seal
80 in the valve 20.
The valve 20C generally operates in a similar manner and to perform
the same functions as the valve 20. The principal distinguishing
features of the valve 20C compared to the valve 20 are the
atmospheric chamber 161 reducing the required dome pressure and the
annular piston 201 which is a safety feature for effecting closure
of the valve in response to an excessively high annulus pressure.
The sealed areas of the valve operator at the seals 154 and 220 are
the same size and, thus, the tubing pressure has no effect upon the
movement of the valve operator. During normal operation, the forces
biasing the valve operator upwardly and, thus, the valve to an open
position comprise the upward force of the spring 183 and the
pressure in the dome chamber 181, while the forces biasing the
valve downwardly to an open position are the forces of the
atmospheric pressure in the chamber 161 and the casing annulus
pressure in the chamber 170. The casing annulus may be used to
control the valve with the force of the casing pressure in the
chamber 171 downwardly on the piston 174 holding the valve operator
at a lower end position for maintaining the valve open. When such
casing pressure is bled off, the spring and dome chamber pressure
lift the valve operator to close the valve in the manner previously
described. In the event of leakage of the ring seal 175, the dome
and annulus pressures are equalized, and the spring 183 lifts the
valve operator to close the valve. Similarly, leakage along the
seals associated with the annular piston 201 will effect the same
pressure equalization to cause closure of the valve by the spring.
Leakage along the seal 220 between the annulus and the tubing
through the valve communicating through the annulus 212 and the
port 213 may equalize tubing and annulus pressure, bleeding off the
annulus pressure to a level sufficient for the spring and dome
chamber pressure to close the valve.
In accordance with a special feature of the valve 20C, the annular
safety piston 201 may be forced upwardly by predetermined high
casing pressure to equalize the dome chamber and casing annulus
pressures for permitting the spring to lift the valve operator and
close the valve. Such a high annulus pressure is applied through
the port 213 and the annular space 212 to the piston 201 in the
skirt 202 over an effective area of the piston defined by seals 203
and 210. When this annulus pressure acting upwardly on the piston
and skirt is sufficiently high to overcome the dome chamber
pressure downwardly on the piston 201 over the area sealed by the
ring seals 203 and 204, the annular piston is moved upwardly. When
the annular piston moves upwardly into the larger annular space
192, the ring seals 203 and 204 no longer can effectively seal
between the valve operator and the valve housing, thereby
permitting an equalization of pressure past the annular piston
between the valve operator and piston and housing. At this upper
position of the piston and skirt, the lower end of the skirt is
above the ring seal 210. The equalization of the annulus and dome
chamber pressures permits the spring 183 to lift the valve operator
to close the valve. The larger area of the piston 201, as compared
with the skirt 202, permits the dome chamber pressure under normal
valve operating conditions to hold the safety piston at a lower end
position without the necessity of utilizing a biasing spring
bearing on the piston.
It is readily apparent from the drawing and foregoing description
of the valve 20C in FIG. 5 that the upper end of the piston 201
must be larger than the lower end of the piston so that the piston
will remain in the sealing position as illustrated when the casing
pressure acting upwardly against the lower end of the skirt exceeds
by even a small amount the charge pressure within the dome chamber
181. It will be obvious that as the lower end of the piston is
reduced in cross sectional area the casing pressure required to
lift and unseal the piston will be increased. Similarly, if the
lower end of the piston is enlarged, the casing pressure to which
the piston responds is decreased. Thus, the sensitivity of this
particular feature of the safety valve is readily adjusted by
varying the ratio between the effective sealed areas of the piston
and skirt portions exposed to the pressure in the chamber 192 and
in the annular space 212.
Another feature of the valve 20C in FIG. 5 which permits variations
in the operating characteristics of the valve is the small annular
chamber 205 below the piston 201 around the piston skirt 202.
Ordinarily this chamber contains atmospheric pressure as the valve
is usually assembled in an environment of air, atmospheric or
ordinary room pressure. Quite obviously, such pressure may vary
with location, altitude, and weather conditions, and the particular
environment of the space in which the valve is assembled may be
changed as desired. For example, the valve may be assembled in a
special chamber in which the pressure is either reduced
substantially by vacuum means or substantially increased for the
purpose of providing a desired pressure in the chamber 205.
A structural alteration which may be made in the valve 20C is
represented in FIG. 9 which shows that portion of the valve
apparatus in the vicinity of the annular piston. All structural
features of the portion of the valve shown in FIG. 9 are identical
to those of FIG. 5 with the exception of the provision of a side
charge port 205a leading to the chamber 205 so that the chamber may
be charged with gas to any desired pressure and sealed by a
suitable plug inserted into the port 205a. Inasmuch as the pressure
within the chamber 205 tends to lift the annular piston in a
direction which unseals the piston, variations in the pressure
within the chamber vary the sensitivity of this particular element
of the valve.
FIG. 6 shows another embodiment 20D of a well safety valve which
includes a valve operator 230 movable in a valve housing 231 for
opening and closing a ball, a poppet, or a flapper type valve. The
operator member structure of the valve 20D is essentially identical
to those of the previously described valves depending upon which
type flow control member is used. The upper end portion of the
valve operator has a thick wall section 232 which slides within an
enlarged bore portion of the valve housing along a housing section
233. A ring seal 234 in an internal annular recess 235 seals
between the valve operator section 232 and the housing wall section
233. Below the housing wall section 233 the valve housing bore is
increased along a wall portion 240 which is spaced from the valve
operator section 232 defining an annular space 241 which
communicates with the annulus through a side port 242 in the valve
housing wall section 240. The valve operator has a piston 243
provided with a ring seal 244 in a recess 245 for sealing between
the piston and the valve housing wall portion 240. The piston
defines the upper end of a dome gas chamber 250 comprising an
annular space between the valve housing wall and the valve operator
below the piston. An internal annular flange 251 is formed within
the valve housing supporting the lower end of a spring 252. The
upper end 253 of the spring engages a downwardly facing shoulder
surface 254 on the bottom of the valve operator piston. The spring
biases the valve operator upwardly toward a valve closed position.
The dome chamber 250 is charged through a side port 255 closed by a
threaded plug 260. Below the internal flange 251 the bore of the
valve housing is slightly enlarged in diameter along a wall portion
261. Below the wall portion 261 the valve housing is slightly
reduced in diameter along a section 262 to an internal shoulder
surface 263 defined between the wall section 262 and a further
reduced diameter portion along a wall section 264. The wall section
264 is provided with a threaded lateral port which has a reduced
smooth internal end portion opening into the bore of the housing
for a shear pin 271 held in position by a threaded plug 272 in the
port 270. An annular piston 273 having a thin-walled lower skirt
portion 274 is slidably disposed around the valve operator wall
section 275 within the valve housing along the housing wall
sections 261, 262, and 264. The lower end portion of the valve
operator wall 275 and the valve housing wall portion 264 are
concentrically spaced apart defining an annular space 276 which is
sealed at atmospheric or some other desired pressure during
assembly of the valve. A lower outer end portion of the piston 273
at the upper end of the skirt 274 has circumferentially spaced
slots 277 which open outwardly and downwardly. The spaces provided
by the slots 277 are at the pressure of the annulus 276 so that the
entire piston 273 over the lower end portions is at the pressure of
the annulus 276 while the upper end of the piston is at the dome
chamber pressure. It will be recognized that the exposure of the
outer portion of the lower end of the piston 273 to the annulus 276
pressure also could be effected by internal slots, not shown, along
the lower end of the interior of the housing wall portion 262
instead of by the use of the piston slots 277. Such an alternative
would, however, be more expensive to machine in the housing
interior than in the piston exterior. The function of the use of a
lower pressure in the annulus 276 and around the piston skirt in
the slots 277 is so that the dome gas pressure above the piston
biases the piston downwardly without the use of a spring. An
internal V-packing assembly 280 seals within the piston 273 around
the valve operator wall portion 275. An external ring seal 281
carried by the piston seals between the piston and the valve
housing wall portion 262, thereby sealing off the lower end of the
charge chamber 250 when the piston is at the lower end position
shown in FIG. 6. The shear pin 271 projects into the bore 282
through the piston skirt portion. The bore 282 is larger than the
shear pin so that pressure is readily communicated through the
piston skirt. The space around the shear pin, together with the
longitudinal slots 277 on the piston 273 and along the piston upper
skirt portion freely communicates the pressure in the chamber 276
over the entire area of the piston sealed by the V-packing 280 and
the external ring seal 281. A second wall portion 283 of the valve
operator is spaced within the housing wall portion 264 defining an
annular chamber 284 in which the piston skirt portion slides. The
chamber 284 communicates with the annulus through a side port 285.
A V-packing 290 is positioned in the annular space at the lower end
of the piston skirt 274 for sealing at the lower end of the skirt
between the valve operator and the valve housing. A ring seal 291
in an external recess on the valve operator below the port 285
seals between the valve operator and the valve housing defining the
lower end of the annular space 284.
The valve housing wall portion 293 below the port 285 is increased
in thickness while the valve operator similarly is increased in
thickness along the portion 294 at the seal 291 so that the
downwardly facing areas of the operator member exposed to tubing
pressure as defined by the line of sealing engagement between the
ring seal 291 and the inner housing wall 293 are the same as the
upwardly facing areas of the operator member as defined by the line
of sealing engagement between the ring seal 234 and the operator
member wall 232. Equalizing the upwardly and downwardly facing
areas of the operator member exposed to tubing pressure neutralizes
any effect of tubing pressure upon the valve operation.
Additionally, the outward movement of the sealing line between the
ring seal 234 and the operator member relative to the line of
sealing between the ring seal 244 and the inner wall of the
housing, as contrasted with the first and second embodiments of the
valve, reduces the effective area of the operator member subject to
casing annulus pressure in the chamber 241. By so reducing such
effective area the required dome pressure in the chamber 250 for
biasing the valve toward a closed position is proportionately
reduced so that the valve is more readily serviceable in the field
at lower pressures.
The operation of the valve 20D is essentially identical to the
operation of the valve 20C with the exception of the fact that the
valve 20D does not include an atmospheric chamber at the upper end
of the valve operator. The valve operator is biased upwardly by the
spring 252 and the dome gas pressure while being held downwardly in
an open position by casing annulus pressure applied through the
port 242 in the annular chamber 241 against the piston 243. Any
conditions which reduce the annulus pressure below a predetermined
level permit the spring and dome pressure to move the valve
operator upwardly closing the valve. Also, seal failures as
discussed with respect to the valve 20 also affect the operation of
the valve 20D causing it to close. Excessive annulus pressures
above a predetermined value apply an upward force in the annular
chamber 284 to the annular piston skirt 274 at the seal 290. When
the force is sufficient on the piston to shear the pin 271, the
piston 273 is forced upwardly into the enlarged wall portion 261 of
the valve housing. When the piston 273 moves into the enlarged
annular space, the seals on the piston are no longer effective, and
the skirt 274 with the seal 290 are moved upwardly from the annular
space 284 into the enlarged annular chamber 276. The casing annulus
pressure is then exerted past the piston and skirt into the dome
gas chamber equalizing the pressure in the chamber with the annulus
pressure so that the spring 252 lifts the valve operator to close
the valve. It will be recognized that without the movement of the
annular safety piston and skirt, the high downward force on the
valve operator piston 243 from the pressure in the annular chamber
241 tends only to hold the valve more firmly in the open position.
It will also be recognized that the atmospheric pressure sealed in
the valve at the surface during assembly in the annular chamber 276
is communicated over the entire area of the piston 273 sealed by
the seals 280 and 281, thus rendering the downward force of the
dome gas pressure more effective on the piston so that a biasing
spring against the piston is not necessary, and the piston tends to
remain firmly in position in the absence of the excessive pressures
required to dislodge it for closing the valve under emergency
conditions. Also, it will be recognized that once closed in this
manner, the valve may not be reopened without removing the valve to
the surface, disassembling it, replacing the shear pin 271 to hold
the annular piston skirt in the lower end sealed position, and
reassembling the valve.
A still further form of well safety valve 20E is illustrated in
FIGS. 7 and 8. The principal distinguishing feature of the valve
20E as compared with the other valves disclosed herein is a
capability of being pumped closed in the event of a valve
malfunction which renders the biasing spring ineffective. Such a
malfunction may include several conditions, such as the lodging of
some obstruction along the valve structure which would require more
force than the spring is capable of delivering to close the valve.
The lower end portions of the valve 20E including the ball valve
structure, the housing, and the operator member below the seal 80
are identical to that shown and described with respect to the valve
20 in FIGS. 1 and 2. Those identical structural features of the
valve 20 shall be referred to by the same reference numerals as
used in FIGS. 1 and 2. The valve has a tubular operator 300
slidably disposed in concentric relationship within a valve housing
301. An O-ring seal 302 is positioned in an internal recess 303 of
the upper end portion of the valve housing sealing around the upper
end of the valve operator in the housing. The valve housing bore is
enlarged in diameter along a thin wall portion 304 spaced in
concentric relationship from the valve operator which has an
external annular dome chamber piston 305 dividing the annular space
between the operator and valve housing into an upper atmospheric
chamber 310 and a dome gas chamber 311. A side port 312 closed by a
threaded plug 313 communicates with the atmospheric chamber 310.
The atmospheric pressure is sealed in the chamber 310 when the
valve is assembled. In inserting the valve operator into the
housing, the plug 313 is removed from the port and replaced after
assembly of the valve, thereby sealing the atmospheric pressure
within the chamber. The piston 305 on the valve operator has a ring
seal 306 in a recess 307 for sealing around the piston with the
inner wall surface of the valve housing section 304. The dome gas
chamber 311 is charged through a side port 314 closed by threaded
plug 315. A coil spring 320 is confined in the dome chamber between
the lower shoulder face 321 on the piston 305 and an upwardly
facing stop shoulder surface 322 on the upper end of an internal
flange 323 within the valve housing below the wall section 304. The
flange 323 has an internal recess 324 for a V-packing assembly 325
held in place by an internal snap ring 330. The packing seals the
lower end of the dome gas chamber 311. Below the flange 323 the
concentric spaced positioning of the valve operator and the valve
housing defines an annular atmospheric chamber 331 communicating
with a side port 332 closed by a threaded plug 333.
The valve operator 300 of the valve 20E has an external annular
operating flange 334 positioned in the annular chamber 331 above an
upper annular operating piston 335 having a head portion 340 and a
skirt portion 341. The piston is releasably locked in place by a
shear pin 342 held between the valve housing and the annular piston
by a threaded plug 343. The upper end of the piston 340 is
engageable with the operating flange 334 on the valve operator for
emergency lifting of the valve operator to close the valve as
discussed hereinafter. A lower concentric valve operator piston 344
is telescoped into the skirt 341 of the upper piston between the
valve operator and the valve housing. The piston 344 has an upper
skirt portion 345 and a lower piston or head portion 350. A
V-packing assembly 351 seals between the lower piston skirt 345 and
the upper piston skirt 341 above a side port 352 leading to an
annular space 353 between the valve housing and the lower skirt 345
extending from the upper end of the piston head 350 to the lower
end of the V-packing 351 for applying the force of casing annulus
pressure to both the upper and lower operator pistons. A ring seal
354 within an annular recess 355 in the lower piston head seals
between the piston and the valve operator member 300. An external
ring seal 360 in a recess 361 of the piston head 350 seals around
the piston head within the valve housing. The space between the
valve operator and the valve housing below the lower piston head
350 communicates with a side port 362 sealed by threaded plug 363
at the surface after assembly under atmospheric conditions so that
the lower end of the piston 350 operates at atmospheric pressure. A
shear ring 364 interconnects the piston head 350 with the valve
operator 300, permitting the lower operating piston to hold the
valve operator downwardly when the annulus pressure is sufficient,
allowing the operator to lift the lower operating piston when the
valve is closed under normal operating conditions, and permitting
excessive annulus pressures to release the operator 300 from the
lower operating piston under emergency conditions.
During normal operation of the valve 20E, which may function in the
same types of well systems as discussed with respect to the other
valves disclosed herein, the valve is biased closed by the spring
320 and the pressure of dome gas in the chamber 311 acting upwardly
on the piston 305. The valve is biased open by annulus pressure
applied through the port 352 into the annular space 353 acting over
an area defined by the sealing engagement between the V-packing 351
and the outer wall of the piston skirt 345 and the inner wall of
the valve housing at the annular chamber 353. So long as this
annulus pressure within the chamber 353 is sufficiently high, the
valve is held open against the spring 320 and the dome chamber
pressure. The annulus pressure holds the piston 344 at the lower
end position of FIG. 7 at which the head of the piston engages the
top surface of the internal flange portion 370 of the valve
housing. The piston holds the valve operator down by means of the
shear ring 364. The upper end of the piston 305 is subjected to
atmospheric pressure in the chamber 310 while, similarly, the
pistons 344 and 335 are exposed to the atmospheric pressure within
the annular chamber 331. When the annulus pressure drops below a
level sufficient to hold the valve open, the dome chamber pressure
in the chamber 311 and the spring 320 lift the valve operator
rotating the ball valve 31 closed. As the valve operator is raised,
the shear pin 364 lifts the piston 344 which travels upwardly with
the valve operator, the skirt 345 of the lower operating piston
moving upwardly in the space around the valve operator within the
upper piston skirt 341 below the upper piston head 340. An increase
in the annulus pressure applied through the side port 352 acts on
the lower operating piston head 350 to force the valve operator
member 300 back downwardly to return the ball valve 31 to the open
position.
When an emergency develops, such as a casing rupture in an offshore
well allowing sea water invasion into the annulus, the valve 20E is
closed if the pressure rises to a predetermined dangerous high
level. When a valve malfunction occurs which prevents the valve
closing under normal reduction of pressure in the annulus, a
controlled annulus pressure increase may be applied from the
surface for the purpose of closing the valve. The increased annulus
pressure applied through the side port 352 into the annular space
353 acts upwardly on the upper operating piston 335 and downwardly
on the lower operating piston 344. The downward pressure on the
lower operating piston holds it against the flange 370, while the
upward force of the high annulus pressure on the upper operating
piston 335 shears the pin 342, forcing the upper piston upwardly
against the operating shoulder 334 of the valve operator 300. The
upper operating piston lifts the valve operator to force the valve
closed. The lifting force of the upper piston on the valve
operator, while the lower operating piston 344 is held down by the
high annulus pressure, shears the ring 364, releasing the valve
operator for upward movement. The upper operating piston then lifts
the valve operator to the position of FIG. 8 closing the ball
valve. The relative positions of the upper and lower operating
pistons after the shear pin 342 and the shear ring 364 are both
severed and the valve is fully closed are shown in FIG. 8. Thus,
the valve may be positively closed by means of the controlled
increase in annulus pressure to overcome an obstruction or other
valve malfunction impairing the normal closing of the valve
responsive to the several conditions discussed with respect to the
other valves.
It will be evident that the various forms of well tubing safety
valves illustrated and described are useful in a multiplicity of
well production and drilling systems for shutting off fluid flow in
response to changes in well operating conditions, the occurrence of
dangerous situations, and valve malfunctions. Also, it will be
evident that each of the valve forms includes features for
emergency valve closure to avert tubing collapse when excessive
annulus pressures are developed. Additionally, at least one form of
the valve includes features which are used for pumping the valve
closed when obstructions or other structural problems preclude
normal closing of the valve in response to the dome chamber and/or
spring.
The various forms of flow control devices embodying the invention
are described herein in terms of the valve housing being an
integral part of a well tubing string. It is to be understood,
however, that the device may be installed in a tubing string at a
suitable conventional landing nipple having side ports and seal
means to provide communication from either a control line or the
casing annulus into the side ports for pressure control of the
device. Additionally, the device may be installed in tubing strings
at landing nipples provided with a sliding sleeve valve which is
closed when the device is not present within the landing nipple. In
accordance with known procedures, such a sleeve valve may be opened
when a device in accordance with the invention is installed in the
tubing string and closed when the device is removed from the tubing
string in order to preclude invasion of the tubing string by the
fluids in the casing annulus .
* * * * *