U.S. patent application number 13/663058 was filed with the patent office on 2014-05-01 for high temperature back pressure valve.
This patent application is currently assigned to VETCO GRAY INC.. The applicant listed for this patent is VETCO GRAY INC.. Invention is credited to Henry X. He, Behrooz A. Movaffagh, Christina Shannon.
Application Number | 20140116720 13/663058 |
Document ID | / |
Family ID | 49578545 |
Filed Date | 2014-05-01 |
United States Patent
Application |
20140116720 |
Kind Code |
A1 |
He; Henry X. ; et
al. |
May 1, 2014 |
High Temperature Back Pressure Valve
Abstract
A back pressure valve for sealing a wellbore. The back pressure
valve has a cylindrical body with threads designed to engage
threads in the opening of a tubing hanger within the wellbore. The
back pressure valve also has a metal sealing surface. When the
threads of the back pressure valve engage the threads in the
opening of the tubing hanger, the metal sealing surface of the
valve seals against the metal of the tubing hanger, forming a metal
to metal seal.
Inventors: |
He; Henry X.; (Edmonton,
CA) ; Movaffagh; Behrooz A.; (Edmonton, CA) ;
Shannon; Christina; (Edmonton, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VETCO GRAY INC. |
Houston |
TX |
US |
|
|
Assignee: |
VETCO GRAY INC.
Houston
TX
|
Family ID: |
49578545 |
Appl. No.: |
13/663058 |
Filed: |
October 29, 2012 |
Current U.S.
Class: |
166/373 ;
166/316; 166/86.1 |
Current CPC
Class: |
E21B 21/10 20130101;
E21B 34/02 20130101; E21B 33/04 20130101; E21B 21/08 20130101 |
Class at
Publication: |
166/373 ;
166/316; 166/86.1 |
International
Class: |
E21B 33/03 20060101
E21B033/03; E21B 34/02 20060101 E21B034/02 |
Claims
1. A back pressure valve for sealing a wellbore, the back pressure
valve designed for installation in a tubing hanger at a. wellhead,
the tubing hanger having an upper end and a lower end, and defining
an opening having a threaded portion and walls that taper outwardly
from a smaller diameter at a downward position toward the lower end
to a larger diameter at an upward position toward the upper end,
the back pressure valve comprising: a substantially cylindrical
body having a threaded portion configured to engage the threaded
portion of the tubing hanger when the valve enters the opening
defined by the tubing hanger; and a tapered metal sealing surface
on the cylindrical body configured to contact the tapered walls of
the opening in the tubing hanger when the threaded portion of the
valve is engaged with the threaded portion of the opening so as to
form a seal between the valve and the tubing hanger.
2. The back pressure valve of claim 1, wherein the tapered metal
sealing surface is tapered at an angle of from 3 to 10 degrees.
3. The back pressure valve of claim 1, further comprising: internal
threads configured for engagement with an installation tool, and
through which the installation tool can provide a torque to the
cylindrical body to engage the threads of the cylindrical body with
the threads of the opening in the tubing hanger until a seal is
formed between the tapered metal sealing surface of the cylindrical
body and the walls of the opening in the tubing hanger.
4. The back pressure valve of claim 1, further comprising: a
sealing groove that circumscribes the cylindrical body and bisects
the tapered metal sealing surface.
5. The back pressure valve of claim 1, further comprising: a poppet
valve having a poppet valve flange and movably contained within the
cylindrical body, the poppet valve having an open position and a
closed position; wherein when the poppet valve is in the open
position, the poppet valve flange is substantially disengaged from
the cylindrical body so that fluid can pass between the poppet
valve flange and the cylindrical body, and when the poppet valve is
in the closed position, the poppet valve flange forms a seal
between the poppet valve flange and the cylindrical body to
prohibit fluid from passing between the poppet valve flange and the
cylindrical body.
6. The back pressure valve of claim 5, further comprising: a spring
surrounding at least a portion of the poppet valve and biased to
urge the poppet valve flange into sealed contact with the
cylindrical body.
7. The back pressure valve of claim 5, wherein the cylindrical body
is composed of metal, and the poppet valve flange is composed of
metal, so that when the poppet valve is in a closed position, the
cylindrical body and the poppet valve flange form a metal to metal
seal.
8. A wellhead assembly including a back pressure valve comprising:
a tubing hanger mounted to a wellhead and defining an opening
having walls, the walls of the opening tapering outwardly from a
smaller diameter within the tubing hanger to a larger diameter at
the top end thereof; and a back pressure valve having a
substantially cylindrical body and a tapered metal sealing surface;
wherein the substantially cylindrical body is configured to
releasably engage the walls of the opening when the back pressure
valve is inserted into the opening; and wherein the tapered metal
sealing surface of the back pressure valve seals against the
tapered walls of the opening when the cylindrical body engages the
walls of the opening
9. The wellhead assembly of claim 8, wherein the opening of the
tubing hanger has a threaded portion and the substantially
cylindrical body has a threaded portion, and wherein the threaded
portions of the opening and the cylindrical body are configured for
releasable engagement when the cylindrical body is inserted into
the opening.
10. The wellhead assembly of claim 8, wherein the tapered metal
sealing surface of the back pressure valve is tapered at an angle
of from 3 to 10 degrees.
11. The wellhead assembly of claim 9, wherein the back pressure
valve further comprises: internal threads configured for engagement
with an installation tool, and through which the installation tool
can provide a torque to the cylindrical body to engage the threads
of the cylindrical body with the threads of the opening in the
tubing hanger until a seal is formed between the tapered metal
sealing surface of the cylindrical body and the walls of the
opening in the tubing hanger.
12. The wellhead assembly of claim 8, wherein the back pressure has
a sealing groove that circumscribes the cylindrical body and
bisects the tapered metal sealing surface.
13. The wellhead assembly of claim 8, wherein the back pressure
valve further comprises: a poppet valve having a poppet valve
flange and movably contained within the cylindrical body, the
poppet valve having an open position and a closed position; wherein
when the poppet valve is in the open position, the poppet valve
flange is substantially disengaged from the cylindrical body so
that fluid can pass between the poppet valve flange and the
cylindrical body, and when the poppet valve is in the closed
position, the poppet valve flange forms a seal between the poppet
valve flange and cylindrical body to prohibit fluid from passing
between the poppet valve flange and the cylindrical body.
14. The wellhead assembly of claim 13, wherein the back pressure
valve further comprises: a spring surrounding at least a portion of
the poppet valve and biased to urge the at least one poppet valve
flange into sealed contact with the cylindrical body.
15. The wellhead assembly of claim 13, wherein the cylindrical body
is composed of metal, and the at least one poppet valve flange is
composed of metal, so that when the poppet valve is in a closed
position, the cylindrical body and the poppet valve flange form a
metal to metal seal.
16. A method of sealing a well with a back pressure valve having
metal sealing surfaces while removing a pressure control adapter
and installing a production tree, the method comprising: inserting
the back pressure valve into the wellhead through the pressure
control adapter so that the metal sealing surfaces of the back
pressure valve sealingly engage metal surfaces of the wellhead;
removing the pressure control adapter from the wellhead; installing
the production tree on the wellhead; and removing the hack pressure
valve from the wellhead.
17. The method of claim 16, further comprising: providing a tubing
hanger in the wellbore defining an opening with threaded surfaces;
providing threads on at least a portion of the surface of the back
pressure valve; and energizing the metal sealing surfaces of the
back pressure valve by engaging the back pressure valve with an
installation tool that provides torque to the back pressure valve
so that the threaded surfaces of the opening engage with the
threaded surfaces of the hack pressure valve.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates generally to back pressure valves for
use in sealing oil and gas wells. More particularly, this invention
relates to back pressure valves that seal wells using high
temperature-resistant metal sealing surfaces,
[0003] 2. Brief Description of Related Art
[0004] Back pressure valves are useful for plugging oil and gas
wells to temporarily contain the wells during, for example, removal
of a pressure control adapter (e.g., a blowout preventer, and
installation of other equipment, such as a production tree).
Typically, back pressure valves are configured to fit into the
opening of the tubing hanger at the wellhead, and are equipped with
elastomeric or other non-metal seals. Such seals prevent the flow
of fluid out of the top of the well by sealing the interface
between the back pressure valve and the production tubing.
[0005] In general, the elastomeric or other non-metal seals used in
back pressure valves are adequate for applications having
relatively low temperatures, such as about 250 degrees Fahrenheit
or below. However, problems arise with such seals when temperatures
exceed about 450 degrees Fahrenheit or more. For example, in wells
where steam assistance gravity drained (SAGD) methods are used,
temperatures often reach levels higher than 450 degrees Fahrenheit
or more. Under such high heat conditions, elastomeric or other
non-metal seals may fail.
[0006] Attempts have been made to improve the durability of
elastomeric seals under high heat conditions by, for example,
designing elastomers with higher heat tolerance, or coating the
elastomeric seals with a heat resistant material. Such attempts,
however, have met with limited success. Alternatively, attempts
have been made to cool the wellhead prior to installation of valves
having elastomeric seals, such as, for example, by pumping cold
water into the well. The downside to this approach, however, is
that the cooling process can be time consuming and expensive. What
is needed, therefore, is a back pressure valve that can effectively
seal the wellhead and that is resistant to high temperature
applications.
SUMMARY OF THE INVENTION
[0007] Disclosed herein is a back pressure valve for sealing a
wellbore that has a cylindrical body configured for insertion into
the opening in a tubing hanger, and that has tapered metal sealing
surfaces. The surfaces taper inwardly in a downward direction. The
back pressure valve also has a threaded portion that corresponds to
a threaded portion of the tubing hanger so that when the threads of
the valve engage the threads of the tubing hanger, the tapered
metal sealing surface is brought into sealing engagement with the
tubing hanger. Thus configured, the wellbore is sealed because
fluid is prevented from flowing between the tubing hanger and the
metal sealing surfaces of the back pressure valve.
[0008] Optionally, the back pressure valve includes a poppet
assembly having a moveable poppet valve with a poppet valve flange.
When the poppet valve flange contacts and seals against the
cylindrical body, the poppet valve is closed and no fluid can pass
between the poppet valve flange and the cylindrical body.
Conversely, when the poppet valve is removed away from the
cylindrical body, the poppet valve is opened, and fluid is allowed
to pass between the poppet valve flange and the cylindrical body. A
spring may surround at least part of the poppet valve and, absent
external forces, is configured to urge the poppet valve flange into
contact with the cylindrical body. In one embodiment, both the
cylindrical body and the poppet valve flange are made of metal, and
when they contact one another they form a metal to metal seal.
[0009] Also disclosed is a method of sealing a well using a back
pressure valve as disclosed herein. The method includes the steps
of inserting the back pressure valve through a pressure control
adapter on the well (such as a blowout preventer) so that the metal
sealing surfaces of the back pressure valve seal against the tubing
hanger, thereby sealing the well. Thereafter, the pressure control
adapter is removed and a production tree may be installed. After
installation of the production tree, the back pressure valve may be
removed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The present invention will be better understood on reading
the following detailed description of nonlimiting embodiments
thereof and on examining the accompanying drawings, in which:
[0011] FIG. 1 is a side cross sectional view of a back pressure
valve according to one possible embodiment of the present
invention;
[0012] FIG. 2 is a side cross sectional view of a back pressure
valve according to the embodiment shown in FIG. 1, with the poppet
valve in an open position;
[0013] FIG. 3 is a side cross sectional view of the back pressure
valve of FIG. 1 inserted into a tubing hanger that has a blowout
preventer mounted to the top thereof; and
[0014] FIG. 4 is an enlarged cross sectional view of the interface
between sealing surfaces of the back pressure valve and the opening
in the tubing hanger according to an embodiment of the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0015] The foregoing aspects, features, and advantages of the
present invention will be further appreciated when considered with
reference to the following description of preferred embodiments and
accompanying drawings, wherein like reference numerals represent
like elements. In describing the preferred embodiments of the
invention illustrated in the appended drawings, specific
terminology will be used for the sake of clarity. However, the
invention is not intended to be limited to the specific terms used,
and it is to be understood that each specific term includes
equivalents that operate in a similar manner to accomplish a
similar purpose.
[0016] Referring to FIG. 1, there is shown a back pressure valve 2
according to one example embodiment of the present technology. The
back pressure valve 2 has a cylindrical body 4 configured to be
inserted into the opening 6 in the tubing hanger 8 of a wellbore
(shown in FIG. 3). The cylindrical body 4 may have internal
shoulders 22. The back pressure valve 2 also includes a metal
sealing surface 10 that in an example tapers inwardly from an upper
end 12 to a lower end 14 thereof. In one example embodiment, the
sealing surface 10 may be tapered at an angle of about 3 to 10
degrees relative to the longitudinal axis 16 of the back pressure
valve 2. In certain embodiments, such as that shown in FIG. 1, the
back pressure valve 2 may also have a hydraulic sealing groove 13
that circumscribes the back pressure valve 2 and bisects the metal
sealing surface 10.
[0017] The back pressure valve 2 additionally has means for
attachment of the valve 2 to the tubing hanger 8, as well as means
for energizing the metal sealing surface 10 into sealed engagement
with surfaces of the tubing hanger 8 (shown in FIG. 3). For
example, with respect to the means for attachment, in the
embodiment shown in FIG. 1 the back pressure valve 2 includes
threads 18 that may be configured to correspond to threads 42
(shown in FIG. 3) in the opening of the tubing hanger 8.
Furthermore, with respect to the means for energizing, the back
pressure valve 2 may have internal threads 20 positioned on an
inner surface 21 of the back pressure valve 2. These internal
threads 20 may be configured for engagement with an installation
tool (not shown). Once the installation tool is engaged with the
internal threads 20, the installation tool can rotate the back
pressure valve 2 until threads 18 fully engage the corresponding
threads 42 in the opening of the tubing hanger 8.
[0018] FIG. 1 also shows a poppet valve 24 that may be included in
the back pressure valve 2. The poppet valve 24 may include a poppet
valve flange 26, and an elongate member 31 that extends from the
poppet valve flange 26 to at or near the bottom end 38 of the back
pressure valve 2. In addition, the poppet valve 24 may include a
spring 28, or other biasing mechanism. The poppet valve flange 26
may have a seal 30 that prevents fluid from passing between the
poppet valve flange 26 and shoulders 22 on the cylindrical body 4
when the poppet valve is closed, as shown in FIG. 1, and as further
described below.
[0019] A spring 28 may surround at least a portion of the elongate
member 31 of the poppet valve 24 to help control the movement of
the poppet valve 24. The spring 28 is bounded at a bottom end by a
spring retention shelf 40 in the cylindrical body 4, and at an
upper end by protrusions 33 extending outwardly from an upper end
of the elongate member 31. Alternatively, the protrusions 33 may be
omitted, and the upper end of the spring 28 may be bounded by the
poppet valve flange 26. The spring 28 is biased so that, in the
absence of external forces, it urges the at least one flange 26 of
the poppet valve 24 into engagement with the shoulders 22 on the
cylindrical body 4.
[0020] Thus configured, the poppet valve 24 has at least a closed
position and an open position. The closed position is the position
shown in FIG. 1, with the poppet valve flange 26 contacting the
shoulders 22 on the cylindrical body 4. When in the closed
position, the at least one poppet valve flange 26 forms a seat with
the shoulders 22, and fluid is prevented from flowing between the
poppet valve flange 26 and the shoulders 22. In an example
embodiment, both the flange 26 and the shoulders 22 are metal, so
that the seal between them is a metal to metal seal. Seals 30 may
supplement this seat and may be made of an elastomer or any other
suitable material.
[0021] Application of an external force may cause the poppet valve
24 to move into an open position, as shown in FIG. 2. For example,
an axial pressure differential on poppet valve 24 may exert a force
on the poppet valve 24 in a downward direction D. When the
magnitude of this downward force exceeds the upward force exerted
on the poppet valve flange 26 by the spring 28 and welt bore
pressure, the poppet valve 24 wilt move downward relative to the
cylindrical body 4. As this happens, the poppet valve flange 26
will move downward into an open position, away from the shoulders
22 on the cylindrical body 4, and fluid will be able to flow
therebetween. Hence, the back pressure valve assembly can be
removed from inside the hanger with a lubricator tool.
[0022] Referring now to FIG. 3, there is shown a back pressure
valve 2 according to an embodiment of the invention, inserted into
an opening 6 of a tubing hanger 8. Also shown is a blowout
preventer 46 mounted above the tubing hanger 8. In this embodiment,
the opening 6 includes threads 42 that are configured for
engagement with the threads 18 of the back pressure valve 2. In
addition, an upper portion 44 of the walls of opening 6 is tapered
outwardly, from a smaller diameter at a downward position toward
the lower portion of the tubing hanger 8 to a larger diameter at an
upward position toward the upper portion of the tubing hanger 8. As
the back pressure valve 2 enters the opening 6, the threads 18 of
the back pressure valve 2 engage the threads 42 of the opening 6.
An installation tool (not shown) then continues to provide torque
to the internal threads 20 until the back pressure valve 2 is fully
threaded into the opening 6 and the metal sealing surface 10 of the
valve 2 contacts the tapered upper portion 44 of the walls of the
opening 6, With the back pressure valve 2 fully in place, the
contact between the metal sealing surface 10 and the walls of the
opening 6 in the tubing hanger 8 form a seal. In embodiments having
a hydraulic sealing groove 13, the hydraulic sealing groove 13 may
serve to enhance the seal and clean the tapered sealing surface,
when the metal sealing surface 10 fully contacts the walls of the
opening 6. With the back pressure valve 2 in place in the tubing
hanger 8 as shown in 3, the opening 6 of the tubing hanger 8 is
sealed and blocks fluid flow between the walls of the opening 6 and
the metal sealing surface 10 of the back pressure valve 2.
[0023] FIG. 4 show an enlarged view of an example interface between
the metal sealing surface 10 of the back pressure valve 2 and the
tubing hanger 8. in FIG. 4, an example of the taper of the metal
sealing surface 10 can clearly be seen. As discussed above, in one
example embodiment, the metal sealing surface is tapered at an
angle of about 3 to 9 degrees.
[0024] One advantage to the back pressure valve disclosed herein is
that the seal between the valve 2 and the tubular hanger 8 is metal
to metal. This means that no elastomeric or other type of seal is
required to seal the interface between the components. The
elimination of elastomers or other non-metal seals is beneficial
because many of those materials cannot withstand high heat
applications. In fact, elastomeric and other non-metal seals are
generally not adapted for use in applications where temperatures
reach 450 degrees Fahrenheit or more. Moreover, while some
specialized elastomeric seals may be able to withstand higher
temperatures, such seals often cannot be used because of economic
or other considerations.
[0025] Some wellhead applications, however, do generate high heat.
For example, steam assistance gravity drained (SAGD) wellhead
applications can generate temperatures of up to 650 degrees
Fahrenheit or more. Therefore, to use elastomeric or non-metal
seals in those applications requires time-consuming cooling
processes, such as pumping cold water through the wellhead, Because
the seals of the valves disclosed herein are made of metal, and can
therefore withstand much higher temperatures, the cooling processes
are unnecessary.
[0026] In addition to the apparatus and assembly shown in FIGS.
1-4, another embodiment of the invention provides a method of
sealing a well with the back pressure valve described above. In
practice, the back pressure valve of the present embodiments may be
used to plug a well during the transition of wellhead operations to
production operations, when the pressure control adapter such as a
blowout preventer (shown in FIG. 3) is removed from the wellhead,
and a production tree (not shown) is installed.
[0027] Initially, the back pressure valve is introduced to the
tubing hanger at the wellhead by attaching the valve to an
installation tool and inserting the valve through the pressure
control adapter. For example, referring to FIG. 3, if the pressure
control adapter is a blowout preventer 46 or lubricator adapter,
the back pressure valve 2 is inserted through the opening 48 that
provides access from the top of the blowout preventer 46 to the
opening 6 in the tubing hanger 8. During this step, the
installation tool may engage the internal threads 20 on the inner
surface 21 of the back pressure valve 2, and may turn the back
pressure valve 2 so that the threads 18 of the back pressure valve
2 engage corresponding threads 42 in the tubing hanger 8. The tool
will e to turn the back pressure valve 2, thereby further engaging
the threads, until the metal sealing surfaces 10 of the valve 2
contact the tubing hanger 8.
[0028] Once the back pressure valve 2 is in place and a seal is
achieved, the pressure control adapter may be removed and a
production tree may be installed without fluid leaking from the
well. After the installation of the production tree, the back
pressure valve 2 may be removed by reversing the above process to
allow oil or gas to flow out of the wellhead.
[0029] While the invention has been shown or described in only
sonic of its forms, it should be apparent to those skilled in the
art that it is not so limited, but is susceptible to various
changes without departing from the scope of the invention.
Furthermore, it is to be understood that the above disclosed
embodiments are merely illustrative of the principles and
applications of the present invention. Accordingly, numerous
modifications may be made to the illustrative embodiments and other
arrangements may be devised without departing from the spirit and
scope of the present invention as defined by the appended
claims.
* * * * *