Subsurface safety valve

There are disclosed two embodiments of a subsurface safety valve having operating means which is responsive to the supply of control fluid from a remote source for holding a closure member in open position and which is retrievable separately from the closure member, so that with the bore of the mandrel above and below the closure member fluidly disconnected, the closure member automatically closes so as to close in the well when the operating means is so retrieved.

This invention relates to a subsurface safety valve having a mandrel 
connected as part of a tubing string packed off within a well bore and 
having a bore therethrough to form a continuation of the bore through the 
tubing string, and means including operating means for respectively 
opening and closing the mandrel bore in response to the supply of control 
fluid thereto or the exhaust of control therefrom. More particularly, it 
relates to an improved subsurface safety valve of the type in which the 
operating means may be retrieved from the well in order to permit its 
replacement or repair without having to pull the tubing string. 
As well known in the art, valves of this general type are useful in 
automatically closing the tubing string in the event of an abnormal 
condition, such as shearing of the tubing string and the line through 
which control fluid is supplied to the operating means. In the particular 
type of subsurface safety valve referred to above, there may also be a 
need to close in the well when the operating means is retrieved, even 
though temporarily, for replacement or repair. 
As shown and described, for example, in U.S. Pat. No. 3,078,923, in one 
version of this latter type of safety valve--i.e., in which the operating 
means is retrievable without pulling the tubing string--the mandrel bore 
is opened and closed by a closure member connected to and retrievable with 
the operating means. Consequently, the bore through the mandrel is left 
open, and the well is not under control, as the need for retrieving the 
operating means arises. 
In another version of this type of safety valve, such as shown in U.S. Pat. 
No. 4,325,431, the operating means comprises a tool which is run into and 
out of a pocket to the side of the mandrel bore separately of the closure 
member, whereby, with the tool in place, there is less restriction of the 
bore of the mandrel than in the mandrel of the above described valve of 
this type. The bore of the mandrel above and below the closure member is 
connected by means including a passageway in the mandrel which is 
controlled by valve means carried by the operating tool so as to close the 
connecting means, until control fluid is supplied to the operating means 
of the tool, and then open the connecting means in order to equalize 
pressure across the closed closure member in order to facilitate its 
opening by a fluid responsive piston within the tool. However, even though 
the closure member automatically closes the mandrel bore as the operating 
tool is retrieved, the passageway is left open by removal of the 
equalizing valve means with the operating tool, so that in this case also 
the well is not closed in during the time the operating means is 
retrieved. 
The primary object of this invention is to provide a subsurface safety 
valve of the type wherein the operating means is retrievable, as in the 
valves above described, but in which the well is automatically closed in 
when the operating means is so retrieved. 
Another object is to provide such a valve wherein, similarly to the 
second-described valve of this type, the operating means comprises a tool 
which is received in a side pocket mandrel, whereby the bore of the 
mandrel is not severely restricted. 
A further object is to provide a valve of the character defined in the 
foregoing object in which, in accordance with one embodiment, the 
operating tool and mandrel thereof are of extremely simple and inexpensive 
construction. 
Yet another object is to provide such a valve in which, in accordance with 
another embodiment thereof, the tool includes valve means for 
automatically equalizing pressure across the closure member as control 
fluid is supplied to the tool in order to open the closure member. 
These and other objects are accomplished, in accordance with the 
illustrated embodiments of the present invention, by a subsurface safety 
valve which includes, as in the above-described valves of this type, means 
including operating means for respectively opening and closing the mandrel 
bore in response to the supply of control fluid thereto from a remote 
source or the exhaust of control fluid therefrom, together with means 
through which control fluid may be supplied to the operating means from 
the remote source, a closure member moveable between position opening and 
closing the mandrel bore, and means yieldably urging the closure member 
toward the closed position. However, in accordance with the novel aspects 
of the present invention, the operating means of each such embodiment is 
removable from the mandrel separately of the closure member to permit the 
closure member to be moved to closed position, and the bore of the mandrel 
above and below the closure member is fluidly disconnected, when such 
closure member is in closed position and the operating means is so removed 
from the mandrel, so that the well is closed in. 
In the preferred and illustrated embodiments of the invention, the mandrel 
includes a pocket to one side of the bore, and the operating means 
comprises a tool adapted to be removably landed in a position within the 
pocket in which the control fluid may be supplied from its remote source 
to a pressure chamber therein and thus to a pressure responsive member 
within the chamber, and having means thereon for moving the closure member 
to open position and holding it in open position in response to the supply 
of control fluid thereto. More particularly, each of the mandrel and tool 
have port means, and the tool carries seal means engageable with the 
pocket to fluidly connect the port means with one another, when so landed, 
and thus confine the flow of control fluid into the pressure chamber. 
In the first-mentioned embodiment of the invention, the valve is of 
extremely simple construction in that the mandrel has no passageway which 
connects the bore above and below the closure member, so that when the 
tool is retrieved and the closure member is in closed position, the well 
will be closed in upon retrieval of the tool. More particularly, the 
operating tool merely includes a pressure responsive member which, 
following pressuring up of the tubing to move the closure member to open 
position, and in response to the supply of control fluid thereto, is 
operable to hold the closure member in open position following pressuring 
up of the tubing to move it to open position. 
In another illustrated embodiment of the invention, the valve is similar to 
that of U.S. Pat. No. 4,325,431 in that a means including a passageway in 
the mandrel connects the bore of the mandrel above and below the closure 
member in its closed position, and the operating tool includes valve means 
which, when the tool is landed within the mandrel pocket, is responsive to 
the supply of control fluid thereto to open the connecting means prior to 
moving of the closure member to open position. More particularly, a 
normally closed check valve is so mounted in the passageway adjacent the 
pocket as to be held open when the tool is landed in the pocket but to 
close when the tool is retrieved, thus closing the passageway and closing 
in the well during the time the tool is retrieved.

With reference now to the details of the above-described drawings, the 
overall valve of the first embodiment of the invention is shown 
diagrammatically in FIGS. 1 and 2 to include a mandrel M adapted to be 
connected as part of a well string (not shown) and having a bore 20 
therethrough which, when the mandrel is so connected, is axially aligned 
with the well string. The valve also includes a closure member 23 mounted 
in the mandrel for movement between positions opening and closing a seat 
about the bore 20, and a tool T for use in operating the valve when landed 
in a pocket 22 of the mandrel to one side of the bore, as shown in FIGS. 1 
and 2. The well string will, as a general rule, be the tubing string of an 
offshore oil or gas well, and the mandrel will be connected as part of the 
tubing string at just below the mud level. 
The closure member 23 is a flapper which is normally urged by a spring (not 
shown) to closed position, as shown in FIG. 1, but which, when moved to 
open position, as shown in FIG. 2, provides a full opening through the 
bore of the mandrel and the tubing string to permit wire line operations 
below the valve. The upper end of the pocket 22 is open, so that, in the 
event one or more parts of the operating tool, and especially the dynamic 
seals thereof, require replacement or repair, the tool need only be 
retrieved from the pocket 22, and then, when reconditioned, run back 
through the bore of the mandrel into landed position within the pocket, 
all in accordance with conventional wire line procedures. 
As in the case of the valve of U.S. Pat. No. 4,325,431, the mandrel M 
includes an outer body 25 which is made up of sections connected in 
end-to-end relation, with the upper and lower ends (not shown) having 
axially aligned openings forming the upper and lower ends of the bore 20, 
and an intermediate section having an inner diameter which is radially 
enlarged and eccentric to the axes of the end openings in the upper and 
lower sections. The mandrel also comprises an inner body 26 having an 
outer diameter which fits closely within the inner diameter of the upper 
portion of the intermediate outer body section, and a bore therethrough 
which is axially aligned with the upper and lower sections of the outer 
body to form a continuation of bore 20. As shown, the pocket 22 of the 
mandrel is formed in the inner body to one side of its bore and thus of 
the mandrel bore 20. 
The valve actuator comprises a tube 28 which is axially reciprocable within 
the outer mandrel body and beneath inner body 26 between an upper position 
(FIG. 1) in which its lower end is above the flapper 23, and a lower 
position (FIG. 2) in which it extends downwardly through the seat in the 
bore to open and hold the flapper to one side of the bore. In this latter 
position, the tube provides a substantially smooth continuation of the 
bore 20 through the mandrel. 
A coil spring 29 is disposed within the annular space between the actuator 
tube 28 and the inner diameter of the outer mandrel body, with the upper 
end of the spring engaging a ring 31 carried by the tube 28 and its lower 
end engaging a ring or collar 30 supported on an upwardly facing shoulder 
of the outer mandrel body so as to urge the tube to its upper position and 
thus permit the flapper to close. As shown in FIG. 1, when the operating 
tool T is landed within the side pocket 22, its lower end is disposed just 
above the ring 31 on the actuator tube so that when a piston is extended 
therefrom in response to control pressure, it will move the tube 
downwardly against the force of the spring 29 in order to open the closure 
member. 
Control fluid for extending the piston, and thus operating the closure 
member, is supplied to a pressure responsive area of the piston within a 
control pressure chamber of the tool through a conduit 32 extending 
downwardly from a suitable source at the surface for connection at its 
lower end with the side pocket. Conduit 32 includes a tube extending 
downwardly along the side of the tubing and connecting at its lower end 
with a drilled hole in the thickened wall of the inner mandrel body. A 
port 32A at the lower end of the conduit 32 connects with the pocket 22 at 
a level opposite a port 32B (FIG. 3) in the landed tool T intermediate 
lower packings 40 and 41, respectively, about the body of the tool. 
The upper end of tool T is specially prepared to receive releasable parts 
of a suitable wire line running tool, which, for example, may be of a type 
shown in U.S. Pat. No. 3,827,490. As described in U.S. Pat. No. 4,325,431, 
the bore 20 of mandrel M is prepared to cooperate with the running tool, 
during running of the operating tool T, to kick the operating tool over 
into a position above the upper end of the pocket 22, or, alternatively, 
during pulling of the operating tool T from the pocket, to kick the tool 
over into the mandrel bore. 
As the operating tool is lowered into pocket 22, a shoulder 35 thereabout 
lands upon a seat about the pocket, and a collar 37 beneath the neck at 
its upper end moves beneath an inner groove 38 formed in the upper end of 
the inner body 26 of the mandrel so as to limit upward movement of the 
tool from its landed position. 
The flapper 23 is pivotally mounted on a pin 40 carried by the thickened 
wall of a housing 41 received within the outer mandrel body for swinging 
into and out of a slot 42 in the housing beneath the pin. When disposed 
within the slot, the flapper is out of the way of actuator tube 28 to 
permit the tube to move through the bore of the housing and thus, when 
fully lowered, to form a continuation of the bore. As shown in U.S. Pat. 
No. 4,325,431, the pivot pin 40 is surrounded by a torsion spring which 
bears at one end of the flapper and at the other end on the housing 41 so 
as to yieldably urge the flapper to the closed position. 
Operating tool T comprises a generally tubular body depending from the 
lower end of a fishing neck 45 at its upper end. Upper and lower packings 
40 and 41, respectively, are carried about the tool body above and below 
part 32B for sealably engaging with the pocket 22 when the tool is landed 
therein above and below the port 32A in the mandrel so as to confine the 
flow of control fluid from conduit 32 into a pressure chamber 46 (FIG. 3) 
within the tool which is closed at its lower end by the pressure 
responsive surface on the upper side of a piston 47 sealably slidable 
within the tubular body, and at its upper end above ports 32B. 
As shown in FIGS. 1 and 3, the lower end of the body of the tool T extends 
below the pocket into the space between tube 28 and the inner diameter of 
the outer mandrel body, and terminates just above collar 31 of the tube 
when the tube is raised to permit flapper 23 to close. As shown in FIG. 3, 
a rod 48 on the lower end of piston 47 extends downwardly within the lower 
end of the tubular body of the operating tool for reciprocation between an 
upper, retracted position in which its lower end is substantially flush 
with the lower end of the tool body (FIG. 3), and a lower, extended 
position in which its lower end projects beyond the lower end of the tool 
body to lower the actuator tube 28 in order to open the flapper, as shown 
in FIG. 2. As also shown in FIG. 3, the lower ends of both the tool body 
and piston extension are spaced a short distance above the upper end of 
collar 31 on the actuator sleeve to enable the operating tool to be landed 
without preloading the spring 29. 
As will be understood, piston 47 has oppositely facing, pressure responsive 
surfaces of equal area on its upper and lower sides which are acted upon 
by control fluid and well fluid within the well tubing above the flapper, 
respectively. Thus, as control fluid is supplied to chamber 46 at a 
pressure sufficient to overcome the force due to pressure in the tubing, 
the lower end of the piston will be extended below the lower end of the 
tool body to engage the collar 31. At this time, however, the upward force 
which the well tubing pressure beneath the flapper is exerting on the 
closed flapper may prevent further downward movement of the actuator tube 
until the pressure across the flapper is equalized. 
Thus, with the lower end of the actuator tube 28 engaged with the top side 
of the closed flapper 23, the tubing string is pressured up above the 
flapper so as to move the flapper away from the seat in the mandrel bore. 
This quickly equalizes pressure across the flapper, so that the force due 
to the piston 47 is effective to swing the flapper into its open position, 
and hold it in such position, whereby pressurizing of the tubing string 
may be discontinued. Thus, as in the case of the valve of U.S. Pat. No. 
4,325,431, the valve is "fail safe" in the sense that the flapper will 
either remain closed or, if open, as above described, will close 
automatically in response to abnormal conditions, including the loss of 
control fluid, as may occur upon shearing of the tubing and control fluid 
conduit 32, whereby water would enter the lower portion of the control 
line and thus the control chamber 46, and/or by the failure of one or more 
of the seals carried by or within the operating tool such that well fluid 
in the tubing beneath the flapper entered the control chamber. 
As previously described, the absence of a passageway in the mandrel 
connecting the mandrel bore beneath the flapper with the pocket 22 (and 
thus the mandrel bore above the flapper) enables the well to be shut in 
despite removal of operating tool T from the pocket. In addition, the 
valve is simple construction in that the tool merely requires a body 
containing an actuating piston and a pressure control chamber on one side 
of the piston to receive control fluid. 
The embodiment of the valve shown in FIGS. 5 to 9 is similar in many 
respects to the above-described valve, as indicated by the ports thereof 
which use the same reference numbers, plus a prime. In other respects, 
however, the valve of FIGS. 5 to 9 is more like that of U.S. Pat. No. 
4,325,431; and, in fact, except for the novel improvements previously 
mentioned and to be described in detail, may be identical to that of the 
patented valve. 
Thus, for example, as indicated by the broken lines of FIGS. 4 and 5, the 
valve includes, in addition to control line 32' connecting at port 32A' 
with pocket 22', a passageway 33 in the mandrel having a port 33A for 
connecting the pocket above the port 32A' with the bore of the mandrel 
beneath flapper 23'. Thus, as shown in FIG. 5, slots 33B are formed in the 
body of operating tool T' intermediate packings 42 and 40' thereabout so 
that, with the tool landed in pocket 22, port 33B is connected to an 
annular conduit 50 within the tool. The upper end of the conduit is in 
turn connected to a port 33C in the tool which leads to the mandrel bore 
above the flapper. 
The conduit 50 is normally closed by valve means (to be described) which is 
adapted to be opened in response to the supply of control fluid in control 
chamber 46'. Upon opening of the valve means, well fluid beneath the 
flapper is free to flow through the passageway 33 as well as the tool 
conduit 50 into the bore of the mandrel above the flapper so as to 
equalize pressure across the closed flapper. As previously described, this 
enables the piston 47' to be freely extended by control fluid in chamber 
46 in order to lower actuator tube 28' through the seat and thereby open 
the flapper and hold it in open position. 
The portions of control fluid conduit 32' and tubing pressure equalizing 
conduit 33 which connect with pocket 22' include holes drilled in the 
thickened wall of the inner mandrel body on opposite sides of the pocket 
(see FIGS. 6 and 7). As shown in U.S. Pat. No. 4,325,431, the lower end of 
conduit 33 may comprise a tube connected at its upper end to the lower end 
of the drilled hole and extending downwardly within a space between the 
actuator tube and the outer mandrel body (see FIGS. 8C and 9) to connect 
with a port in the mandrel housing opening to the recess 42' of flapper 
housing 41' in which the open flapper is received. The upper and 
intermediate packings 42 and 40' surround the tool body above and below 
the slots 33B therein and sealably engage the pocket above and below the 
port 33A, when the tool is landed in the pocket. The upper packing 42 
surrounds the tool body beneath port 33C and seals with the pocket 22' 
beneath the cutout 56. Thus, as will be described to follow, when the 
equalizing valve is open, well fluid in the tubing beneath the flapper is 
confined for flow into the tubing above the flapper. 
As shown in FIGS. 8A and 8B, port 32B' in the tubular body of the operating 
tool connects with control fluid chamber 46' whose upper end includes a 
dome in the tool body beneath the fishing neck thereof. The equalizing 
valve includes a body 51 which is sealably slidable longitudinally within 
the tool body for reciprocation above the piston 47 between positions 
opening and closing annular conduit 50 between the body 51 and the inner 
diameter of the tubular tool body. More particularly, and as will be 
described to follow, the tubular body of the equalizing valve 51 is 
reciprocated between opened and closed positions in response to the 
pressure of control fluid within the chamber 46. 
As shown in FIG. 8B, an intermediate portion of the equalizing valve 55 is 
radially enlarged to provide a shoulder 55 which, in the closed position 
of the equalizing valve, engages the lower end of a seat 56 on the inner 
diameter of the tool body just above slots 33B. The lower end of the 
equalizing valve body beneath shoulder 51 slides within an O-ring 57 
carried on the inner diameter of the tool body beneath the slots 33B, and 
a radially enlarged portion of the equalizing valve body above shoulder 55 
carries a seal ring 58 (FIG. 8A) which sealably engages the inner diameter 
of the tool body above the ports 33C. A passageway 59 through the 
equalizing valve connects with ports 60 in its lower end beneath O-ring 57 
and with ports 61 (FIG. 8A) in an intermediate portion thereof above 
O-rings 58, so as to provide a bypass for control fluid between the lower 
end of the chamber 46' below the valve to the dome at the upper end of the 
chamber. 
For purposes which will be understood from the description to follow, the 
equalizing valve is yieldably urged to its upper seated position by means 
of a coil spring 62 arranged within the upper annular portion of the upper 
end of control chamber between the upper end of the equalizing valve and 
the tubular extension of the body of the operating tool beneath the 
fishing neck at its upper end. As shown in FIG. 8A, the lower end of the 
coil spring engages a ring 63 seated upon an upwardly facing shoulder on 
the inner diameter of the tool body, and the upper end of the spring 
engages a shoulder on the lower end of an enlarged head 64 of the 
equalizing valve. 
The outer diameter of the O-ring 58 is larger than the inner diameter of 
the O-ring 57 so that control fluid is effective over an annular 
cross-sectional area to urge the equalizing valve in a downward direction. 
The area of the seating surface of the shoulder 55 of the equalizing valve 
is larger than either of the aforementioned areas, so that, with the 
flapper closed, the pressure of well fluid in the tubing beneath the 
flapper will urge the equalizing valve in an upward direction to seat with 
a force equal to such pressure times the difference in area between the 
seating surface and the inner diameter of O-ring 56, plus the force of the 
spring 62 urging the equalizing valve body in an upward direction. Hence, 
even if the upward force of the spring 62 is ignored, the tubing pressure 
below the closed flapper will maintain equalizing valve closed until 
control pressure has been raised to a level sufficiently higher than that 
of the tubing pressure (depending on the relationship of the areas of the 
seating surface and within the O-ring 57), and, in any event, to a level 
higher than that required to move the piston 47' downwardly to cause the 
actuator tube to engage the top of the flapper. Thus, as described in 
connection with the valve of FIGS. 1 to 3, the piston is so moved in 
response to a control pressure which may be only slightly greater than 
that of tubing pressure above the flapper, which in turn is normally 
substantially less than tubing pressure beneath the flapper. 
With the lower end of the actuator tube 28' engaged with the top side of 
the closed flapper 23', as shown in FIG. 9, and control pressure raised to 
move the equalizing valve body downwardly, and thus open the lower end of 
conduit 50, well fluid in the tubing beneath the flapper begins to flow 
through the conduit 50 through ports 33C and into the bore of the mandrel 
above the flapper, whereby pressure in the tubing above and below the 
flapper begins to equalize. As will be understood from the description to 
follow, downward movement of the equalizing valve 51 is limited by 
engagement of its lower end with the upper end of piston (see FIG. 9) so 
that the tubing pressure continues to equalize, whereby the piston 47' is 
able to extend further so as to lower actuator tube 28' and thus swing 
flapper 23' to open position, as shown in FIG. 5. As the piston is 
lowered, the equalizing valve also moves downwardly until a tapered 
shoulder 65 (FIG. 8B) thereabout beneath the O-ring 83 seats upon an 
upwardly facing tapered seat 66 on the inner diameter of the body of the 
operating tool just below the ports 33C to reclose the valve. 
In accordance with the novel aspects of the above-described embodiment of 
the present invention, and as shown in FIGS. 6 and 7, a check valve 
element 70 is mounted within port 33A leading from passageway 33 of the 
mandrel to pocket 22' for movement between a position closing the port, as 
shown in FIG. 6, and opening the port, as shown in FIG. 7. As shown, the 
check valve element has a conical shoulder 71, which in its closed 
position, engages a conical seat 72 about the port 33A. More particularly, 
the valve element is urged to closed position by means of a coil spring 73 
acting between it and a wall 74 across the outer end of the port. A stem 
75 which protrudes from shoulder and into a reduced inner end of the port 
33A is of sufficiently smaller diameter than the inner end to permit fluid 
to flow freely between the passageway 33 and the pocket 22' in the open 
position of the valving element. 
When the tool T is landed within the pocket 22, as shown in FIG. 7, its 
side engages the inner end of the stem to urge it outwardly against the 
force of the spring and thus into the open position of FIG. 7 so as to 
fluidly connect the mandrel bore above and below the flapper. Thus, upon 
the supply of control fluid to the control chamber of the tool T', the 
valve means 51 within the tool is caused to open and thereby equalize 
pressure across the flapper. However, upon removal of the tool from the 
pocket 22', the valve element 100 is automatically returned to closed 
position by spring 102 so as to fluidly disconnect the mandrel bore above 
and below the flapper 23', which has automatically returned to closed 
position, and thus close the well in. 
Thus, the above-described valve accomplishes the broad purposes of the 
present invention without sacrificing the ability to facilitate opening 
the flapper by first equalizing pressure thereacross automatically in 
response to the supply of control fluid to the operating tool. In 
addition, of course, in its illustrated form, this valve may be 
constructed with only minor modifications to the valve of U.S. Pat. No. 
4,325,431. 
From the foregoing it will be seen that this invention is one well adapted 
to attain all of the ends and objects hereinabove set forth, together with 
other advantages which are obvious and which are inherent to the 
apparatus. 
It will be understood that certain features and subcombinations are of 
utility and may be employed without reference to other features and 
subcombinations. This is contemplated by and is within the scope of the 
claims. 
As many possible embodiments may be made of the invention without departing 
from the scope thereof, it is to be understood that all matter herein set 
forth or shown in the accompanying drawings is to be interpreted as 
illustrative and not in a limiting sense.