U.S. patent number 3,642,070 [Application Number 05/034,967] was granted by the patent office on 1972-02-15 for safety valve system for gas light wells.
This patent grant is currently assigned to Otis Engineering Corporation. Invention is credited to Warner M. Kelly, Frank H. Taylor.
United States Patent |
3,642,070 |
Taylor , et al. |
February 15, 1972 |
SAFETY VALVE SYSTEM FOR GAS LIGHT WELLS
Abstract
A safety valve system for wells including a valve connected in a
tubing string for shutting off flow to the surface in the tubing.
The valve is biased to an open position by fluid pressure in the
tubing-casing annulus and is closed in response to a predetermined
low pressure in the annulus. The system is particularly adapted to
conversion of existing wells to gas lift by perforation of the
tubing and installation of a safety valve embodying the invention
at the perforation whereby the valve is responsive to lift gas
pressure and closes when the lift gas pressure is reduced below a
minimum value.
Inventors: |
Taylor; Frank H. (Carrollton,
TX), Kelly; Warner M. (Houston, TX) |
Assignee: |
Otis Engineering Corporation
(Dallas, TX)
|
Family
ID: |
21879781 |
Appl.
No.: |
05/034,967 |
Filed: |
May 6, 1970 |
Current U.S.
Class: |
166/372; 166/297;
166/374; 417/111; 166/55.3; 166/322; 417/110 |
Current CPC
Class: |
F16K
11/065 (20130101); E21B 34/105 (20130101); E21B
43/122 (20130101); E21B 2200/04 (20200501) |
Current International
Class: |
E21B
34/10 (20060101); F16K 11/065 (20060101); E21B
43/12 (20060101); E21B 34/00 (20060101); E21b
043/00 () |
Field of
Search: |
;166/297,298,314,315,53,55.1-55.3,72,73,105,106,224 ;175/205
;417/108,109,110,111,115 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Novosad; Stephen J.
Claims
What is claimed and desired to be secured by Letters Patent is:
1. A well installation comprising: a production flow conductor for
movement of well fluids to the surface; means providing an annulus
about said flow conductor into which lift gas under pressure may be
introduced; gas injection means for admitting lift gas from said
annulus into said flow conductor when the lift gas pressure is
within a predetermined range to raise well fluids in said flow
conductor to the surface; and safety valve means in said flow
conductor for preventing fluid flow in said flow conductor to the
surface, said safety valve means including pressure responsive
means communicating with said annulus whereby said lift gas
pressure in said annulus holds said valve means open and releases
said valve means to close when said lift gas pressure drops below
said predetermined operating range during normal gas lift
production in said well installation.
2. A well installation according to claim 1 wherein said safety
valve includes spring means biasing said valve means toward a
closed position in opposition to said lift gas pressure.
3. A well installation according to claim 2 wherein said valve
means includes operator means having a pressure responsive piston
in a chamber adapted to be charged with fluid under pressure for
biasing said operator means toward a valve closed position
supplementing the force of said biasing spring.
4. A well installation according to claim 3 wherein said valve
means includes locking means for releasably locking said valve in
said flow conductor below said gas injection means.
5. A well installation according to claim 4 wherein said locking
means is lockable in a landing nipple in said flow conductor.
6. A well installation according to claim 4 wherein said locking
means includes slip means for supporting said safety valve means
against longitudinal movement along the inner wall surface of a
tubing section of said flow conductor.
7. A well installation according to claim 3 wherein said safety
valve means comprises an elongated body provided with an annular
cylinder, said operator means comprises an operator tube defining
an inner wall of said cylinder and said annular piston is on said
tube in said cylinder, said spring being engaged between said tube
and said body, a valve coupled with said tube for movement between
open and closed positions responsive to movement of said tube,
means for charging said annular cylinder with fluid under pressure
on one side of said piston for biasing said piston in a direction
for moving said operator tube in a direction to close said valve,
and means in said body for communicating said annular cylinder on
the other side of said piston with lift gas pressure in said
annulus when said valve is locked in said flow conductor.
8. A well installation according to claim 1 wherein said safety
valve means is below said gas injection means.
9. A well installation according to claim 1 wherein said safety
valve means is above said gas injection means.
10. A method of preparing a well having a flow conductor and an
annulus around said flow conductor for production by gas lift and
protection against leakage responsive to a loss of lift gas
pressure comprising: perforating said flow conductor at a first
depth to admit lift gas to said conductor from said annulus;
perforating said flow conductor at a second depth below said first
depth; and installing a safety valve in said flow conductor at said
second depth in communication with said annulus through a
perforation in said conductor at said second depth, said safety
valve having means for preventing flow in said conductor when
closed and being adjusted to remain open responsive to lift gas
pressure in said annulus communicated through said perforation
while said pressure is within a predetermined operating range and
to close when said pressure is reduced below a predetermined low
level below said range.
11. A method in accordance with claim 10 including the step of
installing gas lift valve means in said flow conductor at said
first depth for controlling admission of lift gas into said flow
conductor from said annulus.
12. A method in accordance with claim 11 wherein a stop member is
set in said flow conductor at about said second depth, perforating
means is supported on said stop member for perforating said
conductor at said second depth, and said safety valve is supported
on said stop.
13. A method of producing a well by a gas lift methods, said well
having a flow conductor, an annulus around said flow conductor
means in said flow conductor for admission of lift gas to said flow
conductor from said annulus when the lift gas pressure is within a
predetermined range and safety valve means in said flow conductor
below said lift gas admission means and communicating with said
annulus for biasing said valve means open responsive to the
pressure of said lift gas above a predetermined value, said method
comprising: introducing lift gas into said annulus at a pressure
within said predetermined operating range above the pressure at
which said safety valve means closes; holding said lift gas
pressure within said range for holding said safety means open to
permit fluid flow in said flow conductor so long as production by
lift gas means is desired; and permitting said lift gas pressure in
said annulus to decrease below said operating range responsive to a
predetermined operating condition to allow said safety valve means
to close to prevent fluid flow in said flow conductor.
14. A well installation comprising: a production flow conductor for
movement of well fluids to the surface; means providing a flow
passage communicating with said flow conductor and through which
lift gas under pressure may be introduced into said flow conductor
for movement of well fluids to the surface in said flow conductor;
gas injection means for admitting lift gas into said flow conductor
from said flow passage communicating with said flow conductor when
the lift gas pressure is within a predetermined range to raise well
fluids in said flow conductor to the surface; and safety valve
means in said flow conductor for preventing fluid flow in said flow
conductor to the surface, said safety valve means including
pressure responsive means communicating with said flow passage
whereby the pressure of said lift gas in said flow passage holds
said valve means open and releases said valve means to close when
said lift gas pressure drops below said predetermined operating
range during normal gas lift production.
15. A method of producing a well by a gas lift method, said well
having a flow conductor, lift gas injection flow passage means
communicating with said flow conductor, means for admission of lift
gas to said flow conductor from said lift gas flow passage means
when the lift gas pressure is within a predetermined range, and
safety valve means in said flow conductor, said safety valve means
communicating with said lift gas flow passage means for biasing
said safety valve means open responsive to the pressure of said
lift gas above a predetermined value, said method comprising:
introducing lift gas into said lift gas injection flow passage
means at a pressure within said predetermined operating range above
the pressure at which said valve means closes; holding said lift
gas pressure within said range for injecting lift gas into said
flow conductor and holding said safety valve means open so long as
production by lift gas means is desired; and permitting said lift
gas pressure in said lift gas injection passage means to decrease
below said operating range and said predetermined value responsive
to a predetermined operating condition to allow said safety valve
means to close to prevent fluid flow in said flow conductor.
Description
This invention relates to well tools and more particularly relates
to well systems and well safety valves therefor.
It is a particularly important object of the invention to provide a
new and improved safety valve for use in the tubing string of a
well.
It is another object of the invention to provide a safety valve
which is operable responsive to fluid pressure within the
tubing-casing annulus of a well and is particularly responsive to a
predetermined low value of such pressure.
It is another object of the invention to provide a well safety
valve of the character described which is held open by fluid
pressure within the tubing-casing annulus of a well.
It is a further object of the invention to provide a safety valve
of the character described which is especially suited to use in
wells being produced by gas lift methods.
It is another object of the invention to provide a well safety
valve of the character described which is readily installed in an
existing well system.
It is another object of the invention to provide a well safety
valve especially suited for use in wells which are not
satisfactorily operable with conventional safety valves.
It is another object of the invention to provide a well safety
valve which is closed responsive to conditions external of the
tubing string of the well.
It is another object of the invention to provide a well safety
valve of the character described which is biased toward a closed
position by the forces of both a dome gas pressure and a
spring.
In accordance with another object of the invention, a safety valve
of the character described is adaptable for use over a wide range
of tubing-casing annulus pressure conditions by adjustment of the
force required to hold the valve open by changing the pressure of
the dome gas in the valve.
It is another object of the invention to provide a well safety
valve which is operable with gas lift systems using relatively low
lift gas pressures.
It is another object of the invention to provide a tubing safety
valve which is installed and retrieved by usual wire line methods.
The valve is used with a standard form of landing nipple included
in the tubing string or in a side pocket form of landing nipple in
which a packoff assembly is installed in the side pocket to direct
annulus pressure into the valve.
It is another object of the invention to provide a safety valve of
the character described which may be run and set in a tubing which
does not include a landing nipple.
It is still another object of the invention to provide a method of
operating a low production well to increase the flow rate of the
well while protecting the well against conditions which might allow
the well to leak, including positioning a safety valve in the well
tubing, such safety valve being responsive to tubing-casing annulus
pressure for holding the valve open, providing means above the
safety valve for injecting a well-fluid-lifting medium into the
tubing, and introducing a lifting fluid into the casing annulus at
a pressure sufficient to hold the safety valve open and to provide
a lifting force to the well fluids in the tubing.
It is another object of the invention to provide a well system for
safe operation of a low pressure well which includes a tubing
string having a safety valve communicating with the tubing-casing
annulus and adapted to be biased to an open position by fluid
pressure in the annulus, and means above the safety valve for
injecting a lifting fluid from the annulus into the tubing
string.
Additional objects and advantages of the invention will be readily
apparent from reading the following description of devices
constructed in accordance with the invention and by reference to
the accompanying drawings thereof wherein:
FIG. 1 is a schematic view partly in section of one form of well
system embodying the invention;
FIGS. 2, 3, and 4 taken together comprise a view in section and
elevation of a safety valve embodying the invention;
FIG. 5 is a cross-sectional view taken along the line 5--5 of FIG.
3;
FIG. 6 is a cross-sectional view taken along the line 6--6 of FIG.
3;
FIG. 7 is an enlarged fragmentary view in section of the valve
operator tube detent shown in the lower portion of the valve in
FIG. 4;
FIG. 8 is a sectional view along the line 8--8 of FIG. 4 showing
the ball valve of the safety valve at an open position;
FIG. 9 is a fragmentary view in elevation of the lower end portion
of the valve with the housing broken away showing the ball valve
lifted to its closed position;
FIG. 10 is a fragmentary view in section of the ball valve and its
hangers taken at a 90.degree. angle to the view of FIG. 9;
FIG. 11 is a schematic view partly in section of another form of
well system embodying the invention using a side-pocket-type
landing nipple arrangement for supporting gas lift valves and a
well safety valve;
FIG. 12 is an enlarged view, partly in section, taken through an
upper portion of the bottom landing nipple shown in FIG. 11
including the upper end portions of a well safety valve embodying
the invention in the main bore of the nipple and a packoff assembly
in the side bore for directing lift gas pressure to the safety
valve;
FIG. 13 is a view similar to FIG. 12 of the lower portion of the
landing nipple with the intermediate portion of the safety valve
shown in FIG. 12 and the lower portion of the packoff assembly of
FIG. 12;
FIG. 14 is a view in section along the line 14--14 of FIG. 12;
FIG. 15 is an enlarged fragmentary sectional view of the side bore
showing the packoff assembly locking flange;
FIG. 16 is a schematic view, partly in section, of a still further
form of well system embodying the invention;
FIGS. 17 and 19-21 taken together constitute a view partly in
section of a safety valve and supporting assembly embodying the
invention used in the well system of FIG. 16;
FIG. 18 is a view in section along the line 18--18 of FIG. 17;
and
FIG. 22 is a schematic view of a still further form of well system
embodying the invention.
Referring to FIG. 1, a well system 30 for the secondary production
of well fluids by gas lift methods includes a well 31 having a
casing 32 provided with perforations 33 communicating the well with
a fluid-producing formation, not shown. A tubing string 34 for
producing fluids from the well is supported from the surface and
extends downwardly through a suitable packer 35 for sealing between
the well casing and tubing string above the perforations 33.
Included in the tubing string is a standing valve 40 which prevents
backflow from the tubing string into the casing below the packer
toward the well formation. Above the standing valve is a landing
nipple 41 having a side port 42 for admitting lift gas to a well
safety valve embodying the invention supported in the nipple.
Included in the tubing string above the safety valve are suitable
gas lift valves 43 and 44 spaced along the tubing string for
admission of lift gas to the tubing string at different levels
within the well. The tubing 34 is spaced within the casing 32
defining within the casing an annulus 45 through which lift gas
flows from the surface to the valves 43 and 44 which admit the gas
to the tubing string for lifting well fluids within the string to
the surface.
At the surface end of the well casing 32, lift gas is admitted to
the annulus 45 through a line 50 from a controllable gas source 51.
A valve 52 in the line 50 controls the flow of lift gas from the
source 51 through the line 50 to the annulus. The tubing string 34
is connected with a flow line 53 which includes a valve 54 for
controlling the flow of well fluids from the tubing string at the
surface. A casing bleed line 55 having a valve 60 is connected at
the surface into the casing 32 for reducing the fluid pressure in
the annulus 45 to a value sufficient to close the safety valve.
Each of the valves 52, 54, and 60 has an electrical or hydraulic
controller, not shown, connected with a control system 61 which
responds to any desired condition, such as temperature, a low
pressure resulting from a flow line rupture, and the like. The
control system holds the valves 52 and 54 open and the valve 60
closed to permit lift gas to be introduced into the annulus for
recovering well fluids through the tubing string and for holding
the safety valve open. When the safety system 61 reacts to a
condition responsive to which it is desired that the well system be
shut in, the valves 52 and 54 are closed to prevent further
injection of lift gas into the casing and production of well fluids
through the flow line 53 from the tubing string. Simultaneously,
the valve 60 is opened to reduce the pressure within the annulus 45
to a value sufficient to close the safety valve, thereby shutting
in the well at the depth of the safety valve to insure against
escape of fluids from the well.
In FIGS. 2, 3, and 4, a safety valve S1 embodying the invention is
shown releasably locked in the landing nipple 41. The landing
nipple 41 is connected at its upper end into the tubing string 34
by a coupling 62. The landing nipple is connected at its lower end
by a coupling 63 to a portion of the string 34 which extends to the
standing valve 40. The landing nipple 41 has an internal annular
locating and locking recess 63 which receives the locating and
locking keys of a locking mandrel 64 which comprises the upper
portion of the safety valve. The locking mandrel 64 is an Otis Type
X mandrel illustrated and described in further detail in U.S. Pat.
No. 3,208,531 issued Sept. 28, 1965 to J. W. Tamplen. The locking
mandrel has a fishing neck or sleeve 65 provided with an internal
annular locking recess 70 adapted to receive coupling members of a
suitable handling tool, not shown. The fishing neck is threaded on
the upper end of a locking sleeve 71. A locking key carrying sleeve
72 is threaded on a tubular mandrel 73 which has a reduced upper
end portion 74 concentrically disposed within the sleeve 71. The
sleeve 72 has circumferentially spaced windows 74 in each of which
is a locating and locking key 75 engaged with the lower end of an
elongate spring 80 which has an upper hooked end portion 81
inserted into an aperture 82 in the upper end of the sleeve 72.
Further structural details and operational characteristics of the
locking mandrel 64 are contained within the U.S. Pat. No.
3,208,531, supra.
The mandrel 73 has a setscrew hole 83 for a setscrew 83a to hold a
shear pin 85, for locking the mandrel on the suitable running tool,
not shown. An outer portion of a shear pin 85 is shown in FIG. 2,
the inner portion having been severed and removed by the running
tool. An annular packing assembly 90 is disposed on the mandrel 73
for sealing around the safety valve locking mandrel within the bore
of the landing nipple 41. The lower end portion of the mandrel 73
is threaded into a central tubular mandrel 91 which is reduced in
diameter along a middle portion 92 providing a downwardly facing
annular stop shoulder 93 which holds a packing assembly 94 against
upward movement on the central mandrel 91. The mandrel 91 is
further reduced and externally threaded along a portion 93 and is
still further reduced in diameter along a lower end portion 95
defining a downward facing shoulder surface 96 below the threaded
portion 93. The mandrel 91 is secured along its threaded portion 93
into the upper end of a lower central tubular mandrel 100. The
upper end of the mandrel 100 engages and holds the packing 94
against downward movement on the tool. An O-ring seal 101 is
disposed in an internal annular recess of the mandrel 100 to seal
between the mandrel and the mandrel 91 above the threaded portion
93. The mandrels 91 and 100 are spaced apart below the shoulder
surface 95 defining an internal annular chamber 102 between the
mandrels. A lateral port 103 is formed in the mandrel 91 above the
packing 94 for communicating with the landing nipple port 42. The
port 103 communicates with a longitudinal flow passage 104
extending downwardly in the wall of the mandrel 91 and opening
through the shoulder surface 95 into the annular chamber 102
between the mandrels 91 and 100. The mandrel 100 is reduced in
internal diameter defining an upwardly facing shoulder surface 105
which also defines the lower end of the annular chamber 102 between
the mandrels 91 and 100. Below the surface 105 the mandrel 100 is
further reduced in internal diameter providing an internal annular
upwardly facing shoulder 110 engaged by the lower end of the
reduced portion 95 of the mandrel 91 limiting the extent to which
the mandrel 91 is inserted into the mandrel 100. The bore 91a of
the mandrel 91 is slightly smaller than the bore 111 of the mandrel
100 below the shoulder 110, defining a downwardly facing shoulder
surface 112 on the lower end of the mandrel 91. The portion 95 of
the mandrel 91 fits tightly within the bore of the mandrel 100
above the shoulder 110 and carries an external annular O-ring seal
113 for sealing between the mandrels 91 and 100.
The mandrel 100 is threaded at its lower end into a tubular
cylinder housing 114. The mandrel 100 has a longitudinal flow
passage 115 which opens at its upper end through the shoulder
surface 105 into the annulus 102 and at its lower end opens through
the lower end of the mandrel into the bore 120 of the cylinder
housing 114 to provide fluid communication for biasing the safety
valve open as discussed in more detail hereinafter.
A pressure equalization passage 120 extends radially through the
wall of the mandrel 100 below its internal shoulder 110. The
passage 120 opens at its inward end into an internal annular recess
121 and at its outer end through the mandrel into the tubing string
bore. As evident in FIG. 6, the vertical flow passage 115 and the
equalizing passage 120 are circumferentially displaced from each
other so that they do not intersect within the wall of the mandrel.
A tubular equalizing valve 122 is movably disposed in the bore 111
of the mandrel for controlling flow through the equalizing passage
120. The lower end portion of the equalizing valve comprises a
plurality of downwardly dependent circumferentially spaced locking
collet fingers 123 which releasably engage an internal locking
recess 124 formed in the mandrel 100 around its bore 111 for
releasably locking the equalizing valve at its upper closed
position as illustrated in FIG. 3. A pair of external O-ring seals
125 are disposed in external annular vertically spaced recesses of
the valve 122 to seal within the bore 111 above and below the
annulus 121 when the valve is closed so that there is no fluid
communication between the interior and exterior of the safety
valve. The upper end of the equalizing valve has an internal
annular shoulder 130 engageable by a pronglike operator member of
an operating tool, not shown, for moving the equalizing valve
downwardly to an open position uncovering the equalizing passage
120. The mandrel 100 has an internal annular flange 131 providing
an upper internal annular shoulder surface 132 which serves as a
stop engaged by the lower end of the locking collet fingers on the
equalizing valve to limit the downward movement of the equalizing
valve in the bore 111 of the mandrel. The valve 122 equalizes the
pressure between the interior and exterior of the safety valve for
moving the valve in the well tubing, as when pulling the valve from
the tubing. An equalizing valve similar to the valve 122 together
with a tool for moving the valve between its open and closed
positions are illustrated in U.S. Pat. No. 3,273,649 issued to J.
W. Tamplen, Sept. 20, 1966.
A valve operator tube 133 is disposed in concentric spaced
relationship within the bore 120 of the tubular housing 114. An
external annular flange on the operator tube defines an annular
piston 134 supporting an O-ring seal 135 providing a seal around
the piston with the wall of the bore 120. The upper end portion of
the operator tube extends in sealed relationship into the lower end
portion of the bore 111 of the mandrel 100. An internal O-ring seal
140 in an internal annular recess along the lower end portion of
the mandrel 100 around its bore 111 seals between the surface
defining the bore 111 and the external surface of the upper end
portion of the valve operator tube. The concentric spacing of the
valve operator tube and the wall of the bore 120 defines an annular
cylinder chamber 141 which communicates above the piston 134 with
the flow passage 115 in the mandrel 100. As shown in FIG. 4, the
valve operator tube has an external annular flange 142 defining a
downwardly facing stop shoulder 143 engaged by the upper end of a
spring 144 supported at its lower end on a stop shoulder 145
defining the upper end of a reduced bore portion 150 of the tubular
housing 114. The bore of the housing is further reduced along a
short portion 151 of the housing communicating through a gas fill
port 152 with a threaded bore 153 closed by a threaded plug 154. A
gasket 154a seals the bore 153 at the inward end of the plug. An
internal O-ring seal 155 is disposed in an internal annular recess
of the portion 150 of the housing 114 sealing around the valve
operator tube within the housing bore below the gas fill port 152.
The annular cylinder 141a within the housing 114 around the valve
operator tube below the piston 134 comprises a dome gas chamber
which is charged to a desired pressure through the fill port 152.
Fluid pressure communicated from the annulus 45 into the cylinder
141 above the piston 134 biases the valve operator tube downwardly
while the lifting force of the spring 144 and dome gas pressure
within the cylinder 141a below the piston 134 biases the valve
operator tube upwardly.
A detent spring 160 is disposed below the portion 150 in the
housing 114 between the valve operator tube and the housing bearing
at its lower end against an annular spacer ring 161 which engages a
detent ball 162. The housing 114 is provided with an internal
annular detent recess 163 defined at its lower end by a shoulder
164, FIG. 7. Similarly, the valve operator tube 133 has an external
annular detent recess 165 the lower end of which is defined by an
upwardly and outwardly facing annular shoulder 170. At the position
shown in FIGS. 4-7 the detent ball 162 is held by the spring 160
and spacer 161 against the operator tube shoulder 170 below the
shoulder 164 of the housing. The bore of the housing below the
shoulder 164 prevents outward movement of the ball 162 with the
ball preventing upward movement of the valve operator tube until
the ball is lifted above the shoulder 164 at which location the
shoulder 170 cams the ball outwardly into the recess 163 releasing
the valve operator tube to move upwardly. The strength of the
spring 160 is selected to hold the detent ball downwardly until the
upward force on the valve operator tube is in excess of the bare
minimum to close the valve so that when the detent releases the
valve operator tube will abruptly move upwardly to lift the safety
valve to a fully closed position and thus avoid regulating. A
detent similar to that shown in FIGS. 4 and 7 is illustrated and
described in U.S. Pat. No. 3,126,908 issued to G. C. Dickens, Mar.
31, 1964.
A bottom sub 171 is threaded on the lower end of the housing 114,
FIGS. 4 and 9. The sub has a reduced lower bore portion defining an
internal annular flange 172 in the sub. A tubular member 173 is
threaded on the lower end portion of the valve operator tube 133. A
locking ring 173a is threaded on the operator 133 against the top
of the member 173. An external annular recess 174 is formed in the
member 173 spaced from its lower end. An internal annular valve
seat surface 175 is provided on the lower end of the member 173 for
sealing engagement with the outer spherical surface of a ball valve
180. The ball valve is supported from a pair of oppositely disposed
hanger brackets 181, each of which has an internal hanger flange
182 on its upper end portion received within the recess 174 of the
tubular member 173 for supporting the ball valve. Two pins 183
support the ball valve from the hanger brackets. Each pin 183 is
secured through a hanger bracket into a circular recess of the ball
valve. The pins 183 and the ball valve have coincident axes so that
the ball valve rotates between open and closed positions, FIGS. 4
and 9. The ball valve has opposite flat side faces 184 on the sides
of the ball engaged by the pins 183. Oppositely disposed ball valve
alignment pins 185 are secured through the wall of the sub 171
engaging the opposite ball faces 184 to hold the ball and its
support structure against rotation or twisting about the
longitudinal axis of the member 173 as the ball is raised and
lowered between its open and closed positions. A pair of oppositely
disposed operator recesses 190 are formed in the ball through the
opposite side faces 184 to receive two oppositely positioned ball
operator pins 191 which are secured through the wall of the sub
171. The relative positions of the ball hanger pins 183, the ball
alignment pins 185, and the ball operator pins 191 are best
illustrated in FIGS. 8 and 9. As the ball valve is raised and
lowered by its hanger brackets 181, the ball is moved
longitudinally relative to the operator pins 191 engaged in the
ball operator recesses 190 forcing the ball to rotate about the
support pins 183. The ball valve has a bore 192 which is aligned
vertically at an open position as shown in FIG. 4 when the ball
valve is at a lower end location and is rotated to a horizontal
closed position when the ball valve is lifted to an upper end
location as shown in FIG. 9. When the ball valve is closed, the
spherical surface of the ball valve is engaged with the valve seat
175 at the lower end of the tubular member 173 on the valve
operator tube 133. With the bore 192 rotated fully out of alignment
with the bore of the valve operator tube, fluid cannot flow
upwardly past the ball valve into the operator tube, and the safety
valve is closed.
In the well system 30, equipped as illustrated in FIG. 1 with the
landing nipple 41 connected in the tubing string 34 below the gas
lift valves of the system, the well safety valve S1 is installed in
the landing nipple by a suitable running tool for wire line
installation from the surface. A suitable running tool for
installation of the safety valve is illustrated and described at
pages 3,832-3,833 of the 1970-71 edition of The Composite Catalog
of Oil Field Services and Equipment published by World Oil,
Houston, Texas and also in the Tamplen U.S. Pat. No. 3,208,531
supra. The safety valve is prepared for installation by adjusting
the dome gas pressure in the annular cylinder 141a to a value which
sets the closing pressure of the valve slightly below the lowest
normal operating pressure of lift gas in the annulus 45 of the well
system during normal gas lift operation. The safety valve will not
close during normal gas lift operation but only after some
occurrence which causes the lift gas pressure to decrease below its
normal lowest level. The dome gas is introduced into the annular
cylinder 141a by removal of the threaded plug 154 and the gasket
154a from the threaded bore 153 and injection through the fill port
152 into the chamber until the desired pressure is obtained. The
gasket and plug are replaced sealing the dome gas within the
chamber. The safety valve is connected on the running tool by the
shear pin 85 inserted through the screw hole 83 securing the
mandrel of the safety valve with the running tool. The setscrew 83a
is threaded into the hole behind the shear pin to hold the pin in
place during the running and setting of the safety valve. An
equalizing prong is connected on the lower end of the running tool
moving the equalizing valve 122, FIG. 3, downwardly to uncover the
equalizing passage 120 during the running of the safety valve into
the well. An equalizing prong suitable for such use is shown and
described in the Tamplen U.S. Pat. No. 3,273,649, supra. The prong
is supported in the lower end of the running tool and is used to
force the equalizing valve downwardly until its collect fingers 123
spring inwardly and move to the stop shoulder 132. The running tool
with the equalizing prong are used to insert the safety valve to
the operating position in the landing nipple 41. The shear pin 85
is then severed by upward blows and the running tool is withdrawn,
leaving the safety valve locked in the nipple. As the running tool
is lifted, the bottom flange on the equalizing prong engages the
collect fingers 123 on the equalizing valve lifting the valve back
upwardly to its closed position as shown in FIG. 3. The collet
fingers spring outwardly into the recess 124 locking the valve at
its upper closed position and releasing the equalizing prong and
running tool to be lifted from the safety valve bore. Since the
well is not produced by gas lift during the installation of the
safety valve, and the valve is of the normally closed type, the
pressure of the gas in the dome gas chamber and the spring 144 hold
the ball valve 180 at its upper closed position during and after
installation of the safety valve.
The well system is adjusted for the gas lift procedure by closing
the valve 60 in the line 55 to prevent bleeddown of pressure in the
well casing 32. The valve 54 in the flow line 53 is open to permit
production from the well and the flow of lift gas into the annulus
45 is initiated from the source 51 through the open valve 52 in the
line 50. When the pressure of the lift gas increases above the
minimum value at which the safety valve is set to close, the valve
is moved to its open position. The lift gas pressure is
communicated from the tubing-casing annulus through the nipple side
port 42 into the annulus defined between the safety valve mandrel
91 and the inner wall of the nipple between the upper packing 90
and the lower packing 94 on the safety valve mandrel. The pressure
is communicated through the side port 103 in the mandrel,
downwardly through the passage 104, the annular chamber 102, and
the flow passage 115 into the cylindrical chamber 141 above the
valve operator piston 134. When the pressure of the gas in the
chamber 141 is sufficient to exert a downward force on the piston
134 exceeding the force of the dome gas in the cylinder 141a below
the piston and the spring 144, the piston and valve operator tube
133 are forced downwardly. The downward movement of the valve
operator tube lowers the ball valve support structure including the
tubular member 173 and the hangers 181 supporting the ball. As the
ball valve is moved downwardly relative to the fixed operator pins
191, engagement of the operator pins in the recesses 190 forces the
rotation of the ball to the position shown in FIG. 4 to permit full
upward flow through the safety valve. So long as the pressure of
the lift gas in the tubing-casing annulus remains at a value
sufficient to overcome the dome gas pressure and the force of the
spring 144, the safety valve is held at its lower open
position.
When any one of the conditions occurs in response to which it is
desired that the safety valve close, the valve will be permitted to
move to its closed position. For example, if the control system 61
senses a fire in the vicinity of the well, it reacts to close the
gas lift valve 52 and the flow line valve 54 and open the bleed
valve 60. With no lift gas entering the casing annulus and the line
55 open, the lift gas pressure declines in the annulus to a value
below that at which the safety valve is set to close. The pressure
reduction is communicated along the passage route previously
described to the annular cylinder 141 reducing the downward force
on the piston 134 to a value below the upward force from the dome
gas and spring 144 so that the valve operator tube is lifted to
raise and rotate the ball valve closed. Closure may also be brought
about by such factors as structural damage to the well head
equipment to the extent that the casing is ruptured causing a loss
of lift gas pressure sufficient to effect closure of the valve. As
the valve starts to close the detent locking balls 162 are
initially disengaged from the operator tube 133 requiring a force
slightly in excess of that necessary to move the ball valve up to
its closed position. As soon as the detent is disengaged by
compression of the spring 160 and outward camming of the balls into
the recess 163, the operator tube is abruptly moved upwardly
positively rotating the ball valve to its fully closed
position.
When desired, the safety valve may be retrieved from the well
tubing with a suitable pulling tool equipped with an equalizing
probe for engaging the equalizing valve 122 to shift it downwardly
to uncover the equalizing passage 120. The probe moves the
equalizing valve to its lower end position at which the lower ends
of the collet fingers 123 engage the shoulder 132. By equalizing
the pressure within and above the safety valve with the pressure
around and below the valve, the valve is much more readily
withdrawn from the tubing string, especially under conditions where
the valve is immersed in liquid in the well.
Thus, the well system 30 with the safety valve S1 provides safety
against well leakage regardless of flow conditions in the well
tubing. A very low-pressure well which will not shut a conventional
safety valve responsive to tubing conditions may be made safe with
the valve S1. Such a well can be a major pollution problem and
without the well system embodying the invention cannot be produced
with any assurance of leakage control in event damage occurs to the
surface equipment or to the casing leading to the gas lift valves.
With the present system any annulus pressure reduction below a set
value will close the safety valve.
FIG. 11 shows a well system 30A which is similar in structure and
function to the well system 30 with identical components identified
by the same reference numerals as used in FIG. 1. The tubing string
system 34 includes a plurality of spaced side-pocket-type landing
nipples 200 positioned at the proper depths for accommodation of
gas lift valves and a safety valve embodying the invention. With
the exception of the side-pocket-type landing nipples, all of the
remaining equipment included in the well system 30A is identical to
that of the previously described well system 30 shown in FIG. 1. As
shown in FIGS. 12 and 13, each of the landing nipples 200 has a
main bore 201 generally aligned with the axis of the tubing string
34 and a laterally displaced, parallel, vertical side bore or
pocket 202.
In the lowermost landing nipple 200, a safety valve S2 embodying
the invention is releasably locked in the main bore and a removable
plug assembly P is releasably locked in the side bore to direct
fluid pressure from the tubing-casing annulus 45 through a side
port 203 in the nipple to the safety valve for biasing the valve to
its open position. In each of the landing nipples 200 above the
lowermost nipple, a suitable gas lift valve, not shown, is located
in the side bore for directing lift gas from the annulus into the
tubing string in a well-known manner for aiding in the production
of well fluids through the string to the surface.
Referring to FIGS. 12 and 13, the safety valve S2 is functionally
identical to the safety valve S1 and structurally resembles safety
valve S1 in many components which have been referred to by the
reference numerals of FIGS. 1-3 with a prime mark (') added. The
central and lower portions of the valve S2 below the locking
mandrel is essentially identical to the S1 valve structure shown in
FIGS. 3 and 4 and thus is only partially illustrated and will not
be described in detail.
The valve S2 has a lock mandrel including locking dogs 204 which
releasably engage an internal annular locking recess 205 in the
nipple 200 around the main bore 201 for locking the safety valve in
place. The locking dogs are supported from a tubular dog carrier
210 which is slidable on a tubular member 211 threaded into a dog
expander 212 secured on the upper end of the mandrel 91'. The
member 211 has a head section 213 which is connectable with
suitable wire line tools for running and pulling the safety valve.
More specific details of the construction and operation of the
locking mandrel on the valve S2 are shown and described in U.S.
Pat. No. 3,292,706 to G. G. Grimmer et al., issued Dec. 20,
1966.
Fluid pressure to the safety valve piston 134' for holding the
valve open is communicated along a path defined by the valve side
port 103' in the mandrel 91', the vertical flow passage 104', the
annular space around the mandrel portion 95' within the mandrel
101' above the shoulder 105', and the vertical flow passage 115' in
the lower portion of the mandrel 100' into the annular chamber 141'
above the piston 134' between the valve operator tube 133' and the
housing 114'.
The function of the side bore plug assembly P is to direct fluid
pressure from casing annulus 45 through the port 203 and the side
bore 202 to the port 42' leading from the side bore into the main
bore 201 to the safety valve. The plug assembly has an elongated
body 220 on which are secured a pair of vertically spaced seal
assemblies 221 which are disposed above and below the port 203 of
the landing nipple when the plug assembly is locked in operating
position within the nipple as shown in FIGS. 12-13. The body 220
has a pointed lower end portion 222 to aid in guiding the plug
assembly into the side bore during its installation. A drain
passage 202a in the nipple connects the side bore with the main
bore to drain the side bore and equalize pressure across the plug
assembly during insertion and withdrawal.
The upper end portion of the body 220 has an external annular
flange 223 which supports a locking sleeve 224 and a locking ring
225 biased downwardly on the sleeve by a spring 230 held at its
upper end by a flange 231 on the sleeve. The sleeve 224, releasable
secured by a shear pin 232 to the fishing neck portion 233 of the
assembly body, has a central reduced portion 234 and an enlarged
lower end portion 235. The landing nipple 200 is provided with an
arcuate internal locking flange 240 extending approximately
180.degree. around the outside half of the side bore 202 spaced
above the main portion of the side bore defining a locking recess
241 in the landing nipple above the side bore. The lower end of the
recess 241 is defined by a stop shoulder 242 around the side bore
at its upper end.
When the plug assembly P is installed in the side bore by a
suitable standard running tool, the locking ring 225 is held at its
lower end position, FIG. 12, by the spring 230 until the plug
assembly is inserted into the side bore to the depth at which the
locking ring engages the top surfaces of the locking half flange
240. The ring is forced upwardly against the spring 230 until the
ring is around the reduced sleeve portion 234 above the enlarged
lower sleeve portion 235. The half flange cams the locking ring
toward the left as seen in FIG. 12 to an eccentric position
allowing the mandrel and sleeve 224 to move downwardly until the
reduced sleeve portion 235 extends slightly below the locking half
sleeve. The spring 230 manipulates the locking ring downwardly past
the half sleeve and back over the enlarged sleeve portion 235. A
peripheral segment of the ring is then engaged in the locking
recess 241 below the flange 240 and the ring is disposed over the
enlarged portion 235 of the plug assembly mandrel so that the ring
cannot be moved sidewardly or eccentrically and thus it engages the
lower surfaces of the locking half sleeve holding the plug assembly
at its operating locked position as shown in FIG. 12. The plug
assembly cannot be released and retrieved from the side bore until
the sleeve 234 is lifted shearing the pin 236. When the sleeve is
lifted above the locking ring, the ring may be cammed sidewardly by
the flange 240 as the tool is lifted releasing the assembly and
allowing it to be lifted from the side bore.
When the plug assembly is locked in position in the landing nipple
as shown in FIG. 12, the upper and lower packing assemblies 221 are
disposed above and below the side port 203 of the landing nipple
defining an annulus 250 around the body 220 within the bore 202
extending from above the side port 203 to below the internal port
42' between the two bores of landing nipple. The landing nipple has
an internal annular recess 251 around the side bore 202 at the port
203 and, similarly, an internal annular recess 252 around the main
bore 201 at the internal port 42'. These annular recesses
facilitate distribution of the fluid pressure from within the
casing annulus 45 along the desired paths to the chamber 141' to
bias the safety valve S2 open. The annulus 252 around the main bore
is particularly required to insure communication from the port 42'
to the port 103' in the safety valve body as the safety valve may
not necessarily be locked with the port 103' circumferentially
oriented as illustrated. The port 103' may be misaligned from the
port 42' and thus it is essential that the pressure be communicated
around the safety valve body between the ports through the annular
recess 252.
A well installation which may be equipped to provide the system 30A
of FIGS. 11-15 will generally initially have the tubing string 34
including properly positioned side pocket nipples 200. In the
absence of such landing nipples one of the other well systems
disclosed herein will most likely prove more economical to adapt to
the well safety system of the invention. Thus, with the side pocket
landing nipples installed in a well as shown in FIG. 11, the
surface portion of the system is connected as illustrated and
described and suitable standard side pocket type gas lift valves
are installed in the side bores 202 of landing nipples other than
the lowermost nipple. Such valves may be of the type manufactured
and sold by Otis Engineering Corporation under the trademark
Spreadmaster and illustrated at page 3922 of the 1970-71 edition of
The Composite Catalog of Oil Field Equipment and Services, supra.
Such gas lift valves control the admission of lift gas from the
annulus 45 through the ports 203 into the main bore of the landing
nipple. The safety valve 52 and the plug assembly P are installed
in the main and side bores, respectively, of the lowermost landing
nipple 200 as shown in FIGS. 12 and 13. As previously indicated,
suitable standard running tools are used for the installation of
both well tools.
With the valves 52 and 54 open and the valve 60 closed lift gas is
injected into the casing annulus 45 for gas lifting well fluids
through the tubing string 34. The lift gas enters the side ports
203 of those nipples equipped with gas lift valves for controlled
injection of the gas into the tubing string. The lift gas pressure
is communicated through the side port 203 of the lowermost landing
nipple and downwardly through the annulus 250 around the mandrel of
the plug assembly P between its upper and lower seal assemblies 221
into the port 42' connecting the side and main bores of the landing
nipple. The lift gas pressure is communicated through the landing
nipple annulus 252 into the safety valve side port 103', downwardly
through the vertical passage 104' into the connecting passage 115',
and into the annular cylinder 141' above the valve operator tube
piston 134'. The pressure of the lift gas on the operator piston
forces the piston downwardly in opposition to the dome gas pressure
below the piston and the spring 144 opening the ball valve 180. So
long as the casing-annulus pressure is sufficient, the safety valve
remains open permitting continuous operation of the gas lift
system. Any occurrence which causes a reduction of lift gas
pressure in the annulus 45 by either a rupture of the casing at the
surface or a bleeding down of the casing pressure through the line
55 responsive to a condition such as a fire sensed by the system 61
causes a lowering of the pressure of the lift gas so that the
safety valve is no longer biased open and is lifted and rotated to
its closed position by the force of the dome gas pressure and the
spring 144.
Referring to FIG. 16, a still further form of well system 30B
embodying the invention includes substantially identical components
as included in the well system 30 shown in FIG. 1. All identical
elements are referred to by the same reference numerals as used in
FIG. 1. The essential difference in the well system 30B is that a
landing nipple for a safety valve was not included in the initial
well installation, but on the contrary a continuous tubing string
34 was provided below the lowermost gas lift valve with no
provision for the landing of a safety valve within the tubing
string or any form of communication between the tubing string and
the annulus 45 below the gas lift valves. In accordance with the
invention the tubing string 34 below the lowermost gas lift valve
in the system 30B is provided with a perforation 260 formed in the
tubing by suitable standard procedures to permit fluid
communication between the casing and the tubing below the lowermost
gas lift valve to admit lift gas pressure to the safety valve for
holding the valve open during the gas lift procedure.
In providing the perforation 260, a lower removable stop or anchor
member L, FIGS. 20 and 21, is set in the tubing string below the
location at which the perforation 260 is desired for supporting the
perforator and subsequently supporting the safety valve within the
tubing. Referring specifically to FIG. 21, the anchor includes a
slip unit 270 having a lower tubular portion 271 and upper
expandable circumferentially spaced locking fingers 272. The slip
unit is disposed on a tubular expander mandrel 273 having a lower
internal sleeve portion 274 provided with an external annular
flange 275. The flange 275 is initially secured to the member 271
by a shear pin 280 in the bore 281. In FIG. 21 the pin has been
sheared and the slips set. The outer portion of the shear pin
remains in threaded bore 281 while the inner end portion of the pin
280 remains in the blind bore 280a of the flange 275. An internal
lock wire 282 is engaged in an annular recess within the tubular
portion 271 around the tubular member 274 above the flange 275 to
prevent disengagement of the slip unit from the expander mandrel
and allow the mandrel to lift the slip unit when the flange 275 is
raised to engage the lock wire 282. The expander mandrel has an
upwardly and outwardly tapered portion 383 which effects expansion
of the slips 272 when the mandrel is driven downwardly in the slips
as shown in FIG. 21. The expander mandrel has an upper internal
shoulder 284 adapted to support a tool such as a perforator and
subsequently a safety valve. A lower anchor of similar design and
operation is shown in U.S. Pat. No. 2,393,404 issued to Herbert C.
Otis on Jan. 2, 1946.
Referring to FIGS. 17-20, a safety valve S3 embodying the invention
is supported in the tubing on the lower anchor L for shutting off
flow in the tubing string 34 responsive to a predetermined low
pressure in the casing annulus 45. The safety valve is similar in
construction and function to the valves S1 and S2 and, thus, the
same reference numerals as used on the valves S1 and S2 are used to
designate corresponding parts of the safety valve S3 with a double
prime mark (") being appended thereto. That portion of the safety
valve S3 illustrated in FIG. 20 including the mandrel 100" and
extending downwardly through the equalizing valve 122", the valve
operator tube 133", and the ball valve 180 is identical to the
structure of the safety valves S1 and S2, as described and
illustrated in more detail previously herein, especially FIGS.
3-10.
Referring particularly to FIGS. 19 and 20, a sleeve 285 is threaded
into the upper end of the mandrel 100" and is provided with an
upper enlarged annular head portion 290, FIG. 19. The sleeve 95" is
concentrically disposed within and spaced from the sleeve 285. The
ring seal 113" seals around the lower end portion of the sleeve 95"
within the mandrel 100", FIG. 20. The lower end portion of the
sleeve 95" serves as an upper stop for the equalizing valve 122". A
ring seal 291 disposed in an internal annular recess of the sleeve
head 290 seals around the upper end portion of the sleeve 95"
within the head 290. The concentric spacing of the sleeve 95"
within the sleeve 285 and the mandrel 100" defines an annular
vertical flow passage 104" which communicates fluid pressure from
the tubing perforation 260 downwardly through the mandrel flow
passage 115" into the annular piston 141" for biasing the safety
valve toward its open position. A port 292 communicates through the
sleeve 285 into the flow passage for admitting casing pressure to
the flow passage 104".
A seal assembly including an expandable seal 293 is supported on
the sleeve 285 for sealing around the safety valve within the
tubing below the perforation 260 when the valve is in operating
position within the tubing string. The seal 293 is confined between
a lower one way seal unit 294 including a ring seal 295 on the
upper end of the mandrel 100" and a similar upper one way seal unit
300 having a ring seal 301 on the sleeve 285 at the upper end of
the seal 293. The seal unit 294 includes an annular ring 294a
having an internal annular recess for the ring seal 295 and a
spacer ring 295a. The ring 294a rests on a spacer ring 296. The
seal 294 permits fluid pressure to enter the expandable seal 293
from below the seal while precluding flow downwardly so that the
seal 293 may be expanded by a higher pressure from below the seal
to prevent flow from below the seal to above the seal. Similarly,
the upper seal unit 300 includes a ring portion 300a housing the
ring seal 301 and a spacer ring 301a and permits a higher pressure
from above the seal 293 to enter the seal and expand it preventing
flow from above the seal to below it under conditions where the
higher pressure is above the seal. The ring 300a comprises a part
of a seal expander and lock 302 which is slidable on the sleeve 285
so that it is forced downwardly against the seal 293 to expand it
to a sealed relationship within the tubing. Locking balls 303 are
confined around the sleeve 285 by a locking sleeve 304 telescoped
over the upper end portion of the sleeve 285 and extending
downwardly around the locking balls and the expander 302. The
sleeve 304 engages the seal expander 302 at the lower end of the
sleeve as shown in FIG. 19 for expanding and holding the seal 293
at a position at which the locking balls 303 are disposed between
aligned recesses in the sleeves 285 and 304 against locking
shoulders therein. The locking sleeve 304 has an internal recess
305 which permits outward expansion of the locking balls 303 when
the sleeve is lifted to align the recess with the locking balls so
that the expander 302 is released to allow relaxation of the seal
293 in pulling the safety valve from the well bore. Further
structural and functional details of the one way seals 294 and 300
along with the related expanding and locking structure, are shown
and described in U.S. Pat. Nos. 3,227,462 and 3,278,192, issued to
J. W. Tamplen, Jan. 4, 1966 and Oct. 11, 1966, respectively.
A tubular connector 310 is threaded into the upper end of the
locking sleeve 304. A seal is provided between the connector 310
and locking sleeve 304 by a ring seal 311 supported in an external
annular recess of the connector. A tubular mandrel 312 is threaded
along its lower end portion into the upper end of the connector
310. An expandable seal 313 is disposed on the mandrel 312 between
upper and lower one-way seal units 314 and 315 respectively. The
lower seal unit 315 includes an annular ring 320 having an internal
recess 321 which accommodates a ring seal 322 below a special
spacer ring 323 which allows pressure to be communicated around the
ring seal 322. The seal unit 315 is supported on a spacer ring 324
resting on the upper end of the tubular connector 310. The spacer
ring 324 allows fluid pressure to be transmitted behind the ring
320 into the seal 313 for expanding the seal responsive to pressure
below the seal. Similarly, the upper seal unit 314 includes a ring
325 having an internal recess 330 which accommodates a ring seal
331 supported on a spacer ring 332 which permits pressure to be
transmitted from above the seal 313 into the seal to expand it
responsive to fluid pressure above the seal. Circumferentially
spaced locking fingers 333 are formed on and extending upwardly
from the ring member 325 for coacting with locking balls 334. A
locking sleeve 340 is telescoped over the mandrel 312 and the
expander 326 for locking and releasing the seal 313. The lower end
of the locking sleeve 340 is engageable with the expander ring 325
for locking the seal 313 in an expanded condition. The locking
sleeve has an internal annular recess 341 which allows the locking
balls 334 to move outwardly for releasing the expander 326 and the
seal 313 to relax the seal 313 for removal of the safety valve from
the tubing string. In the particular relative position of the seal
locking parts shown in FIG. 19, the locking balls 334 are held
inwardly by the locking sleeve 340 whereby the balls engage the
locking shoulder 313 on the mandrel 326 holding the expander 326
locked downwardly. The mandrel 312 has an external annular shoulder
342 at its upper end engageable by an internal shoulder 343 when
the locking sleeve 340 is lifted for removing the tool from the
well bore. Structural and operational details of the locking parts
for the seal 313 are illustrated and described in the U.S. Pat.
Nos. 3,227,462 and 3,278,192, supra.
An upper holddown member 350 having a tubular portion 351 and
upwardly extending slips 352 is threaded into the upper end of the
locking sleeve 340. A slip expander and handling sub 360 is
telescopically engaged within the member 350 and held by a locking
wire 361 inserted through a hole 361a in the member 350. The lower
tubular portion 362 of the handling sub has an external annular
flange 363 which is secured by a shear pin 363a to the member 350
during installation of the safety valve. The shear pin 363 threads
through the bore 364 of the member 350 with the inward end portion
363a of the shear pin engaging a recess 365 in the flange 363 for
holding the handling sub at an upper position relative to the slips
during installation. The handling sub has a tapered slip expander
portion 370 which is above the slips 352 when the handling sub and
the slip unit are shear pinned together during insertion of the
safety valve into a well bore. After the shear pin is severed, the
handing sub is forced downwardly in the slips and the slip expander
portion 370 enters and expands the slips to engage the tubing wall
for holding the safety valve against upward movement.
The well system 30B contemplates an initial well installation with
the lift valves 44 without a safety valve and, thus, for safety
considerations may not be produced by gas lift methods. Such a well
might flow at a rate which is not justified economically but which
could become a major problem if leakage occurred and which can be
efficiently produced by gas lift methods. The bottom anchor L, FIG.
21, is installed in the tubing string below the gas lift valves at
the depth at which safety valve is to be set. A suitable perforator
is inserted supported on the bottom anchor perforating the tubing
at 260, FIG. 16. The perforator is then removed and the safety
valve S3 is installed by means of a suitable wire line running tool
with the lower end of the bottom member 171" of the safety valve
resting on the shoulder surface 284 at the upper end of the bottom
anchor L. With the safety valve housing held against further
downward movement, a downward force on the handling mandrel 360 by
the running tool sequentially expands and locks the lower seal 293,
the upper seal 313 and shears the pin 363a so that the handling
mandrel is forced downwardly into and expanding the slips 352
locking the safety valve against upward movement. The well is then
produced by lift gas methods as previously discussed with the
pressure of the lift gas communicated to the safety valve through
the perforation 260 holding the safety valve open so long as lift
gas pressure is present in the annulus. The annulus pressure is
communicated into the tubing through the perforation 260 into the
annular space around the safety valve between its upper and lower
seals 313 and 293 from which it is communicated along the
previously described paths to the operator tube piston for biasing
the valve open against the dome gas and spring pressures. The
safety valve closes in the same manner as previously discussed when
the pressure within the annulus is decreased below the
predetermined level at which the safety valve is adjusted to
operate. The safety valve may be removed with a suitable pulling
tool engaged with the operator mandrel 360. In lifting the safety
valve the flange 363 on the operator mandrel engages the wire 361
and the valve is raised with the slips 352 being free to move
inwardly and the seals 313 and 293 being sequentially released and
permitted to deflate. A suitable operating prong on the pulling
tool shifts the equalizing valve 122" to its lower end open
position so that a column of liquid does not have to be lifted by
the safety valve as it is withdrawn from the tubing.
Another form of well system 30C embodying the invention is
illustrated in FIG. 22. The well system 30C is essentially the same
as the system 30B shown in FIG. 16 except that it does not include
the gas lift valves 44. Corresponding components of the systems 30C
and 30B are denoted by the same reference numerals as used in FIG.
16. Basically, the well system 30C contemplates a flowing
low-pressure well which may be accelerated by gas injection without
conventional gas lift valves. The tubing is perforated by
conventional means at 400 to admit gas from the casing annulus 45
to the tubing string to aid in lifting well fluids to the surface.
The perforation 400 may have orifice inserts such as illustrated
and described in detail along with apparatus and techniques for
installation of the inserts in U.S. Pat. No. 3,111,989, issued to
J. W. Tamplen, Nov. 26, 1963. The well system 30C also includes a
safety valve S3, FIGS. 17-21, which is installed in the tubing
string below the perforation 400. The structure, function, and
installation and removal of the safety valve S3 have been described
in connection with the well system 30B.
The operation of the well system 30C is basically identical to the
operation of the system 30B. The safety valve S3 is installed and
functions in the same manner as in the system 30B. Lift gas is
introduced into the annulus and passes into the tubing string
through the perforations 400 holding the safety valve open. It will
be recognized that in this particular well installation well fluids
may flow through the perforation 400 into the casing annulus, which
does not occur in the other installations disclosed herein due to
the presence of the gas lift valves having check valves which would
preclude flow from the tubing into the casing annulus. However,
with the safety valve S3 in the tubing below the perforations, any
occurrence which decreases the annulus pressure sufficiently to
close the safety valve will result in the stoppage of any flow into
the annulus since the safety valve is below the perforations.
A still further form of well installation embodying the invention
and utilizing the well system 30C as illustrated and described
includes gas lift valves in the tubing in communication with the
perforations 400. Gas lift valves which may perform such a function
and be installed in the tubing string without a landing nipple
includes a packoff anchor having expandable seals spanning the
tubing perforations as described and illustrated in U.S. Pat. No.
3,278,192 issued to J. W. Tamplen, Oct. 11, 1966. The Tamplen
pack-off anchor with gas lift valve is adapted to be installed at a
tubing coupling with the locking bosses 207 of the assembly engaged
in the coupling recess to lock the assembly against longitudinal
movement. In the absence of such a coupling at the depth desired
for the gas lift valves, a retrievable concentric Otis packoff gas
lift assembly utilizing upper and lower slip type stops may be
installed in the tubing string at the perforations. Such an
assembly is illustrated and described at page 3921 of the 1970-71
Edition of The Composite Catalog of Oil Field Equipment and
Services, supra. The use of such an assembly together with the
safety valve S3 permits the conversion of a well to gas lift where
the well installation previously had no facilities for gas
lift.
While the safety valve has been illustrated and described as below
the gas lift valves in each system, it may be positioned above the
gas lift valves where those valves have check valves to prevent
backflow. Such an arrangement would generally insure that the
safety valve would always be above the liquid level in the annulus
and would simplify setting the opening conditions for the safety
valve.
It will now be seen that new and improved well systems for
conversion of existing wells to gas lift procedures including
safety means to insure against inadvertent leakage due to equipment
damage and malfunction have been described and illustrated. It will
be seen that such systems include safety valves which are operable
responsive to the tubing-casing annulus pressure, independent of
flow conditions within the tubing string of the well so that a well
is shut in by such a safety valve in response to any condition in
the annulus which reduces its pressure below a predetermined level.
Such a casing responsive safety valve permits safety control of
even wells which flow at an extremely low rate and consequently
would not close conventional safety valves which respond to flow
rate and pressure changes within a well tubing. The valve does not
require that a column of liquid extending to the surface be lifted
for the valve to close. The valve employs the combined forces of
dome gas pressure and a spring to move it from an open to a closed
position with adjustability of the dome gas pressure providing
maximum flexibility in the conditions under which the valve is
usable since the closing pressure for the valve is readily changed
by change of the dome gas pressure. In one form of well
installation embodying the invention, the safety valve is supported
in a conventional landing nipple below regular tubing-type gas lift
valves. In another form of installation, the safety valve and gas
lift valves are supported in side-pocket-type landing nipples
included in the production string. In a still further form of well
system embodying the invention, a tubing having no landing nipples
is perforated for lift gas injection and for a safety valve which
is supported on slips in the tubing. In each system the safety
valve is held open by lift gas pressure in the normal operating
range and released to close when the lift gas pressure is reduced
below the lower value in such range.
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