U.S. patent application number 15/736562 was filed with the patent office on 2018-07-12 for improved pressure barrier system.
The applicant listed for this patent is Enovate Systems Limited. Invention is credited to Sven Ivar Fure, Michael O'Sullivan, Robin Slater.
Application Number | 20180195362 15/736562 |
Document ID | / |
Family ID | 53784908 |
Filed Date | 2018-07-12 |
United States Patent
Application |
20180195362 |
Kind Code |
A1 |
Slater; Robin ; et
al. |
July 12, 2018 |
Improved Pressure Barrier System
Abstract
A production apparatus (120) configured to be connected to an
emergency disconnect package (EDP) (135), comprises a housing (190)
defining a wellbore (161); a first wellbore valve member (361) for
closing the wellbore, the first wellbore valve member provided
within the housing, the first wellbore valve member being capable,
in use, of shearing an object located in the wellbore; and a second
wellbore valve member (162) for closing the wellbore, the second
wellbore valve member provided within the housing, the second
wellbore valve member being capable, in use, of shearing an object
located in the wellbore. The provision of a production apparatus
with wellbore valve members and being directly connectable to the
EDP, obviates the need for a lower riser package (LRP) which would
normally provide the required emergency shearing/cutting and
sealing functionalities.
Inventors: |
Slater; Robin; (Houston,
TX) ; Fure; Sven Ivar; (Houston, TX) ;
O'Sullivan; Michael; (Aberdeen, UK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Enovate Systems Limited |
Aberdeen, Aberdeenshire |
|
GB |
|
|
Family ID: |
53784908 |
Appl. No.: |
15/736562 |
Filed: |
June 16, 2016 |
PCT Filed: |
June 16, 2016 |
PCT NO: |
PCT/GB2016/051804 |
371 Date: |
December 14, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 33/06 20130101;
E21B 33/064 20130101; E21B 33/063 20130101; E21B 34/04 20130101;
E21B 47/06 20130101; E21B 19/10 20130101; E21B 34/16 20130101; E21B
33/068 20130101 |
International
Class: |
E21B 33/06 20060101
E21B033/06; E21B 33/068 20060101 E21B033/068; E21B 19/10 20060101
E21B019/10; E21B 47/06 20060101 E21B047/06; E21B 33/064 20060101
E21B033/064 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 17, 2015 |
GB |
1510673.5 |
Claims
1. A production apparatus configured to be connected to an
emergency disconnect package (EDP), the production apparatus
comprising: a housing defining a wellbore; a first wellbore valve
member for closing the wellbore, the first wellbore valve member
provided within the housing, the first wellbore valve member being
capable, in use, of shearing an object located in the wellbore; and
a second wellbore valve member for closing the wellbore, the second
wellbore valve member provided within the housing, the second
wellbore valve member being capable, in use, of shearing an object
located in the wellbore.
2. A production apparatus according to claim 1, wherein in an open
configuration, the first wellbore valve member and the second
wellbore valve member allow flow of fluid through the wellbore, and
wherein in a closed configuration, the first wellbore valve member
and the second wellbore valve member prevent flow of fluid through
the wellbore.
3. (canceled)
4. (canceled)
5. A production apparatus according to claim 1, wherein the first
wellbore valve member comprises a first gate, and wherein the
second wellbore valve member comprises a second gate, wherein the
first gate and the second gate are moveable in different directions
transverse to the wellbore between a wellbore open position and a
wellbore closed position.
6. (canceled)
7. (canceled)
8. A production apparatus according to claim 1, wherein the first
wellbore valve member is coupled to and/or associated with a first
actuator, and wherein the second wellbore valve member is coupled
to and/or associated with a second actuator.
9. (canceled)
10. (canceled)
11. A production apparatus according to claim 8, wherein the first
actuator and the second actuator are operable automatically and
independently of each other.
12. A production apparatus according to claim 8, wherein each of
the first actuator and the second actuator comprises two separate
actuation mechanisms.
13. A production apparatus according to claim 12, wherein each of
the first actuator and the second actuator comprises a first,
electric, actuation mechanism and a second, mechanical, actuation
mechanism.
14. (canceled)
15. A production apparatus according to claim 1, wherein the
production apparatus further comprises a gripping mechanism
configured for gripping and/or catching an object within the
wellbore.
16. A production apparatus according to claim 15, wherein the
gripping mechanism is located below the first wellbore valve member
and the second wellbore valve member.
17. (canceled)
18. A production apparatus according to claim 15, wherein the
gripping mechanism actuator is automatically operable and/or
activated via a command signal.
19. A production apparatus according to claim 1, wherein the
production apparatus comprises an emergency disconnect package
(EDP) connector for connecting to the EDP.
20. (canceled)
21. (canceled)
22. A production apparatus according to claim 1, comprising a
disconnect actuator capable of causing disconnection between the
EDP and the production apparatus.
23. A production apparatus according to claim 22, wherein the
disconnect actuator is automatically operable and/or activated.
24. A production apparatus according to claim 1, further comprising
an intervention isolation device axially spaced and located above
the first wellbore valve member and/or second wellbore valve
member.
25. (canceled)
26. A production apparatus according to claim 1, wherein the
production apparatus comprises and/or is associated with a pressure
control device capable of controlling and/or regulating pressure
within a portion of the production apparatus and/or downstream of
the production apparatus.
27. A production apparatus according to claim 26, wherein the
pressure control device comprises a production line configured for
allowing flow of fluid to and/or from the wellbore, the production
line being connected to the wellbore at a location between the
intervention isolation device and the first wellbore valve member
and/or second wellbore valve member.
28. A production apparatus according to claim 1, wherein the
production apparatus comprises and/or is associated with a control
system for automatically controlling actuation and/or operation of
the first wellbore valve member and of the second wellbore valve
member.
29. A production apparatus according to claim 28, wherein the
control system is configured for automatically operating the first
actuator and the second actuator.
30. A production apparatus according to claim 28, wherein the
control system is further configured for automatically controlling
actuation of the gripping mechanism.
31. A production apparatus according to claim 30, wherein the
control system comprises and/or is provided with a work-over mode,
wherein when in work-over mode, the gripping mechanism actuator can
be activated and/or operated by the control system, and wherein,
when not in work-over mode, the gripping mechanism actuator is not
activated and/or operated.
32. A production apparatus according to claim 30, wherein the
control system comprises and/or is provided with a production mode,
wherein when in production mode, the gripping mechanism actuator is
not activated and/or operated by the control system, and wherein
when not in production mode, the gripping mechanism actuator can be
activated and/or operated.
33. A production apparatus according to claim 28, wherein the
control system comprises one or more sensors configured to monitor
and/or measure one or more predetermined parameters, the one or
more sensors being located in the wellbore and/or in one or more
conduits associated with and/or in fluid communication with the
wellbore.
34. (canceled)
35. (canceled)
36. A production apparatus according to claim 33, wherein the
control system comprises three or more sensors configured to
monitor and/or measure pressure.
37. A production apparatus according to claim 33, wherein the
control system comprises one or more control modules in
communication with one or more sensors.
38. A production apparatus according to claim 33, wherein the one
or more sensors are located downstream of the pressure control
device, first wellbore valve member and/or second wellbore valve
member.
39. (canceled)
40. (canceled)
41. A production apparatus according to claim 37, wherein the
control module(s) initiates actuation of one of more actuators when
pressure above a predetermined threshold has been detected by a
predetermined number of the sensors.
42. (canceled)
43. A production apparatus, the production apparatus comprising: a
housing defining a wellbore; a first wellbore valve member for
closing the wellbore, the first wellbore valve member provided
within the housing, the first wellbore valve member being coupled
to a first actuator; a second wellbore valve member for closing the
wellbore, the second wellbore valve member provided within the
housing, the second wellbore valve member being coupled to a second
actuator, wherein the first wellbore actuator and the second
wellbore actuator each have at least two separate actuation
mechanisms.
44. A production apparatus, the production apparatus comprising: a
housing defining a wellbore; a first wellbore valve member for
closing the wellbore, the first wellbore valve member provided
within the housing, the first wellbore valve member being capable,
in use, of shearing an object located in the wellbore; and a second
wellbore valve member for closing the wellbore, the second wellbore
valve member provided within the housing, the second wellbore valve
member being capable, in use, of shearing an object located in the
wellbore; and a gripping mechanism disposed within the housing and
configured for gripping and/or catching the object within the
wellbore.
45. A subsea assembly comprising a production apparatus according
to claim 1.
46. A method for closing a wellbore in a production apparatus, the
method comprising: providing a production apparatus configured to
be connected to an emergency disconnect package (EDP), the
production apparatus comprising a housing defining a wellbore; a
first wellbore valve member for closing the wellbore, the first
wellbore valve member provided within the housing, the first
wellbore valve member being capable, in use, of shearing an object
located in the wellbore; and a second wellbore valve member for
closing the wellbore, the second wellbore valve member provided
within the housing, the second wellbore valve member being capable,
in use, of shearing an object located in the wellbore; and
actuating and/or operating the first wellbore valve member and the
second wellbore valve member.
47. A method for resuming production following a safety event, the
method comprising, in sequence: closing the/a pressure control
device; opening a first wellbore valve member and a second wellbore
valve member, the first wellbore valve member and the second
wellbore valve member being configured for closing a wellbore and
being capable, in use, of shearing an object located in the
wellbore, the first wellbore valve member and the second wellbore
being provided within a housing of a production apparatus
connectable to an emergency disconnect package (EDP).
Description
FIELD OF INVENTION
[0001] The present invention relates to production apparatus and to
related well production methods and systems. More particularly, but
not exclusively, the invention relates to production methods and
systems for use on subsea wells.
BACKGROUND TO THE INVENTION
[0002] Offshore production assemblies typically comprise a number
of components including, but not limited to:
[0003] a well extending below the seabed to a hydrocarbons
reservoir; and
[0004] a wellhead typically located at an upper portion of the well
and/or near the seabed and providing structural and/or sealing
functionality with respect to one or more production components
such as casing, liners, tubing, etc.
[0005] The control of fluids, in particular in production wells
where produced hydrocarbons flow from the well, and in injection
wells where a fluid or a gas is injected into the well, is
generally achieved by the provision of a production tree or
so-called "Christmas tree". The production tree is typically
located on the seabed on top of a subsea well extending into the
seabed, and in such instance is termed a subsea production tree.
The production tree is typically connected to and/or placed on the
wellhead or on a tubing head spool supporting a tubing hanger.
[0006] The production tree also constitutes a barrier between the
well and the downstream environment. The production tree may
comprise a single bore or a dual bore and is typically equipped
with well control barriers to maintain adequate sealing integrity
and reliability. A typical configuration of such a subsea tree
entails dual valves vertically stacked between a horizontal tubular
that transmits the flow of fluids or gases from or into the subsea
well and an isolation valve mounted below the subsea tree connector
for well intervention operations.
[0007] However, such typical valves assemblies used in subsea
production trees for well fluid and pressure containment and
isolation have limited capability to provide the shearing/cutting
and sealing functionality to provide sufficient safety to
personnel, oil installations and environment during production and
intervention operations required in case of emergency.
[0008] Under current practice, well control during intervention
operations is performed by a Completion Work-Over Riser (CWOR)
system.
[0009] A CWOR system provides a conduit from a surface vessel to a
subsea well for communication of fluids and well intervention tools
and services that can be conveyed on slickline, eline, coil tubing
or jointed tubulars. CWOR systems typically contain a Lower Riser
Package (LRP) that includes the safety devices that seal the well
bore and permit disconnection of the CWOR system from the subsea
production tree in event of an emergency situation, essentially
replicating the functions of a blowout preventer (BOP) stack as
used during well drilling and completion operations.
[0010] The Lower Riser Package (LRP) of the CWOR system, in either
single or dual bore configurations, comprises: [0011] A tree
connector which connects to the subsea production tree; [0012] A
lower riser package body (LRP body) having a lower profile that
connects to the tree connector with an integral annulus with at
least one annulus isolation valve, and an upper profile that
connects to an emergency disconnect package (EDP). The LRP body
includes one or more LRP sealing elements operated by hydraulic or
electrical actuation and whereby one or more of the sealing
elements comprise a shearing/cutting element that may be a gate
valve, ball valve, ram valve or other type of valve or combinations
thereof. Typically at least one valve, such as a ram valve or gate
valve, in the LRP is designated as a safety head with the purpose
of providing the shearing/cutting function of the system; [0013] An
emergency disconnect package (EDP) connected to the upper profile
of the LRP, the EDP comprising a body having a quick disconnect
connector at or near a lower end thereof, and a profile that
connects with a riser at or near an upper end thereof. The EDP
typically includes EDP sealing elements; and [0014] A riser having
a riser connector at or near its lower end that connects to the
EDP. The riser typically has a pressure-containing tubular that
provides a pressure containment system from subsea to surface.
[0015] The current practice for subsea systems is to ensure that
all of the pressure retaining elements of the subsea system are
capable of operating with the maximum expected full shut-in
wellhead conditions generated by the reservoir pressure and
temperature. As reservoir pressures and temperatures increase and
the full shut-in pressure at the wellhead rises beyond the
capability of conventional well control and pressure retaining
equipment, costs to develop and manufacture new equipment increase
significantly the system costs for both the production and workover
intervention systems.
[0016] In particular, there is a desire in the industry to design
downhole systems and assembly capable of operating at very high
pressure, for example in excess of 15 kpsi, e.g., up to 20 kpsi. As
a consequence, all equipment exposed to high pressure must be rated
to the maximum expected pressure. As subsea well pressures increase
beyond 15 kpsi, the cost of pressure rating subsea equipment to
full shut in wellhead pressure renders some oil and gas reserves
un-economic to develop.
[0017] It is an object of the present invention to eliminate or
mitigate one or more of the disadvantages associated with the prior
art.
SUMMARY OF THE INVENTION
[0018] According to a first aspect of the present invention there
is provided a production apparatus configured to be connected to an
emergency disconnect package (EDP), the production apparatus
comprising:
[0019] a housing defining a wellbore;
[0020] a first wellbore valve member for closing the wellbore, the
first wellbore valve member provided within the housing, the first
wellbore valve member being capable, in use, of shearing an object
located in the wellbore; and
[0021] a second wellbore valve member for closing the wellbore, the
second wellbore valve member provided within the housing, the
second wellbore valve member being capable, in use, of shearing an
object located in the wellbore.
[0022] The production apparatus may be and/or may be termed a
"Christmas tree".
[0023] The production apparatus may be located subsea, e.g., at or
near and upper end of a subsea well.
[0024] The provision of a production apparatus, e.g. subsea tree,
with wellbore valve members having shearing and sealing
functionality, and being directly connectable to the EDP, obviates
the need for a lower riser package (LRP) which would normally
provide the required emergency shearing/cutting and sealing
functionalities. This permits reduction in weight, cost and
complexity of the overall assembly, e.g. CWOR. As such, the
apparatus may define and/or may function as a combined or
integrated production and intervention apparatus.
[0025] In one embodiment, the production apparatus may be
connectable to and/or may be placed on top of a wellhead. The
production apparatus may comprise a wellhead connector for
connecting to the wellhead.
[0026] In another embodiment, the production apparatus may be
connectable to and/or may be placed on top of a tubing head spool.
The production apparatus may comprise a tubing head spool connector
for connecting to the tubing head spool.
[0027] In an open configuration, the first wellbore valve member
and the second wellbore valve member allow flow of fluid, e.g.,
hydrocarbons, through the wellbore.
[0028] In a closed configuration, the first wellbore valve member
and the second wellbore valve member prevent flow of fluid, e.g.
hydrocarbons, through the wellbore.
[0029] Preferably, the first wellbore valve member and the second
wellbore valve member may be rated to the maximum expected full
shut-in wellbore conditions, e.g. maximum expected wellbore
pressure. By such provision, closure of one or both of the first
wellbore valve member and the second wellbore valve member protects
the equipment above and/or downstream of the first wellbore valve
member and/or second wellbore valve member. The first wellbore
valve member and the second wellbore valve member may be rated up
to about 15 kpsi, preferably up to about 20 kpsi.
[0030] In one embodiment, the first wellbore valve member may be
provided within and/or may define a first wellbore valve. The
second wellbore valve member may be provided within and/or may
define a second wellbore valve.
[0031] In another embodiment, the production apparatus may comprise
a wellbore valve comprising the first wellbore valve member and the
second wellbore valve member. In such instance, the first wellbore
valve member and the second wellbore valve may form part of and/or
may be provided within the wellbore valve. The first wellbore valve
member may be or may comprise a first gate. The second wellbore
valve member may be or may comprise a second gate.
[0032] The first wellbore valve member, e.g. first gate, and the
second wellbore valve member, e.g. second gate, may be located
within a wellbore valve housing.
[0033] The first gate and/or the second gate may be moveable in a
direction transverse to the wellbore between a wellbore open
position and a wellbore closed position. Advantageously, the first
gate and the second gate may be moveable in different directions
transverse, e.g. substantially perpendicular, to the wellbore
between a wellbore open position and a wellbore closed
position.
[0034] The wellbore valve may further comprise a first seal seat
for forming a seal with the first gate in the wellbore closed
position to seal the wellbore.
[0035] The wellbore valve may further comprise a second seal seat
for forming a seal with the second gate in the wellbore closed
position to seal the wellbore.
[0036] In one embodiment, the first gate and the second gate may be
capable, in use, of shearing an object, e.g. a tubular, located
between the first and second gates, e.g. located within the
wellbore.
[0037] The first wellbore valve member and/or the second wellbore
valve member may be capable, in use, of shearing an object, e.g., a
tubular, located in the wellbore.
[0038] The first wellbore valve member, second wellbore valve
member, first gate, and/or second gate may comprise a shearing end
or shearing face capable of shearing an object, e.g., a tubular,
located in the wellbore. It will be understood that shearing an
object, e.g. a tubular, located in the wellbore, may be required in
workover mode, e.g., during intervention operations, when an object
such as a tubular is or has been inserted in the wellbore to
perform a given intervention task. However, during normal
production operations, a tubular would typically not be present in
the wellbore, and closure of the first wellbore valve member,
second wellbore valve member, first gate, and/or second gate would
therefore not cause shearing of such a tubular.
[0039] In one embodiment, the wellbore valve may be a valve as
described in International Patent Application Publication No. WO
2008/035091 (Edwards), which is incorporated herein by reference in
its entirety, for example as valve as marketed by Enovate Systems
Ltd under the trade name En-Tegrity. In such instance, the first
wellbore valve member may comprise a first gate having a shearing
face and a sealing portion or surface, and the second wellbore
valve member may comprise a second gate having a shearing face and
a sealing portion or surface. The wellbore valve may comprise a
first seal seat for forming a seal with the first gate in the
wellbore closed position to seal the wellbore. The gates may be
axially moveable with respect to the wellbore, permitting the gates
to move into a sealing engagement with one of the seal seats under
the action of an external force, such as an applied pressure.
[0040] Advantageously, the first wellbore valve member and the
second wellbore valve member are actuatable and/or operable
independently of each other.
[0041] The first wellbore valve member may be coupled to and/or
associated with a first actuator.
[0042] The second wellbore valve member may be coupled to and/or
associated with a second actuator.
[0043] The first actuator and the second actuator may be operable
independently of each other.
[0044] In normal operating conditions, the first actuator and/or
the second actuator may be activated and/or may be operable by a
user. The first actuator and/or the second actuator may be operable
hydraulically, electrically, or the like.
[0045] In an emergency situation, for example following detection
of pressure over a predetermined threshold, the first actuator
and/or the second actuator may be activated automatically.
[0046] The first actuator and/or the second actuator may be
automatically activated by reception of a command signal, e.g., of
an electrical signal. The first actuator and/or the second actuator
may be automatically activated through loss of a command signal,
e.g., of an electrical signal.
[0047] Automatic activation and/or operation of the first actuator
and/or of the second actuator may automatically cause a respective
first valve member or second valve member to move to a closed
position.
[0048] Preferably, the first actuator and the second actuator may
be operable automatically and independently of each other. By such
provision, two or more independent failsafe barriers may be
provided within the production apparatus, e.g., Christmas tree.
This ensures compliance with the provision of two independent
failsafe barriers, as required by API Standards. This obviates the
need for equipment located downstream of the production apparatus
to be rated to the maximum expected pressure. This also obviates
the need for a separate LRP to be provided between the EDP and the
production apparatus to ensure well isolation in case of an
emergency during intervention operations.
[0049] In use, while the present production apparatus meets the API
Standards requirement for two independent failsafe barriers,
closure of either of the first wellbore valve member or the second
wellbore valve member may prevent flow of fluid, e.g.,
hydrocarbons, through the wellbore.
[0050] In an embodiment, automatic activation of the first actuator
and/or second actuator may mechanically operate the first actuator
and/or second actuator, for example by releasing a torsion
spring.
[0051] The first actuator may comprise two separate actuation
mechanisms, e.g., a first actuation mechanism and a second
actuation mechanism.
[0052] The second actuator may comprise two separate actuation
mechanisms, e.g., a first actuation mechanism and a second
actuation mechanism.
[0053] Advantageously, each of the first actuator and the second
actuator may comprise two separate actuation mechanisms.
[0054] The first actuation mechanism of the first actuator and the
first actuation mechanism of the second actuator may be the same or
different.
[0055] The second actuation mechanism of the first actuator and the
second actuation mechanism of the second actuator may be the same
or different.
[0056] In an embodiment, the first actuation mechanism may comprise
an electric actuation mechanism. In another embodiment, the first
actuation mechanism may comprise a hydraulic actuation
mechanism.
[0057] The second actuation mechanism may comprise a mechanical
actuation mechanism, e.g. a spring. In an embodiment, the second
actuation mechanism may be activated upon loss of an activating
means to the first actuation mechanism, e.g. upon loss of
electrical supply to electric actuation mechanism, or upon loss of
hydraulic supply to the hydraulic actuation mechanism.
[0058] By such provision, the first and/or second actuator,
advantageously each of the first and second actuators, may be
provided with two separate actuation mechanisms which may help
ensure actuation of the first and/or second actuator in an
emergency, even in the event of a loss of power and/or hydraulic
supply to the first actuation mechanism.
[0059] In an embodiment, the first actuator and/or the second
actuator may comprise an actuator as described in US Patent
Application Publication No. US 2012/0234117 A (Oswald), which is
incorporated herein by reference in its entirety. In such instance,
the actuator may comprise an electric drive containing both an
electric drive mechanism and control electronics used to open and
close an associated valve gate under electric power as well as
compressing a spring in a spring chamber. During initialisation of
the actuator the spring may be compressed and mechanically latched
in position by latch. Following initialisation the electric drive
may be used to open and close valves in normal operation using
non-fail safe control methods while the spring may remain
compressed. A latch release mechanism consisting of a hammer held
by a continuously powered solenoid may be released on loss of power
to the solenoid, e.g., in an emergency situation. The latch release
may dis-engage the mechanical latch and may release the spring to
operate the actuator and close the valve gate.
[0060] In another embodiment, automatic activation of the first
actuator and/or second actuator may hydraulically operate the first
actuator and/or second actuator.
[0061] Hydraulic actuation may be accomplished by the release of a
fluid at high pressure to a pressure chamber of the first actuator
and/or second actuator, e.g., to move a piston of the first
actuator and/or of the second actuator thereby forcing a respective
first valve member and/or second valve member to its closed
position.
[0062] Hydraulic actuation may be accomplished by the influx of a
fluid at high pressure generated by a subsea pump to a pressure
chamber of the first actuator and/or second actuator, e.g., to move
a piston of the first actuator and/or of the second actuator
thereby forcing a respective first valve member and/or second valve
member to its closed position.
[0063] The production apparatus may further comprise a gripping
mechanism configured for gripping and/or catching an object, e.g.,
a tubular, within the wellbore. It will be understood that gripping
and/or catching an object, e.g., a tubular, located in the
wellbore, may be required in workover mode, e.g. during
intervention operations, when an object such as a tubular is or has
been inserted in the wellbore to perform a given intervention task,
and closure of the first wellbore valve member and/or the second
wellbore valve member causes shearing of the tubular. However,
during normal production operations, a tubular would typically not
be present in the wellbore, and actuation of a/the gripping
mechanism would therefore not be necessary.
[0064] The gripping mechanism may be moveable between a retracted,
non-engaged configuration and a deployed, engaged configuration.
When in said engaged configuration, the gripping mechanism may
apply a gripping force to the object, e.g., tubular.
[0065] The gripping mechanism may be located below the first
wellbore valve member and the second wellbore valve member. By such
provision, upon actuation of the first wellbore valve member and/or
the second wellbore valve member, causing the object, e.g., the
tubular to be severed, the gripping mechanism may prevent the
severed object from falling down the wellbore.
[0066] In the engaged configuration, the gripping mechanism may be
adapted to center the object, e.g., tubular within the
wellbore.
[0067] The gripping mechanism may comprise a plurality of gripping
elements.
[0068] The gripping elements may be spaced apart from one another.
Conveniently, the gripping elements may be circumferentially
disposed relative to the wellbore.
[0069] In one embodiment, one or more gripping elements, e.g. each
gripping element, may be adapted to rotate or pivot around its own
rotation axis from the retracted configuration to the deployed
configuration. In use, upon deployment, one or more gripping
elements, e.g., each gripping element, e.g., a gripping portion
thereof, may pivot or rotate towards a central portion of the
wellbore and/or towards the object.
[0070] In another embodiment, one or more gripping elements, e.g.,
each gripping element, may be adapted to move radially transverse
to the wellbore axis from the retracted configuration to the
deployed configuration. In use, upon deployment, one or more
gripping elements, e.g., each gripping element, e.g., a gripping
portion thereof, may move radially transverse to the wellbore axis
towards a central portion of the wellbore and/or towards the
object.
[0071] In one embodiment, one or more gripping elements are locked
in the deployed configuration by the weight of the object.
[0072] In another embodiment, one or more gripping elements are
locked in the deployed configuration, e.g., by a locking mechanism
such as a mechanical locking mechanism.
[0073] In one embodiment, the gripping mechanism may comprise a
gripping mechanism as described in International Patent Application
Publication No. WO 2011/039512 (Edwards et al.), which is
incorporated herein by reference in its entirety.
[0074] The gripping mechanism may be actuated by an emergency
event, e.g., by detection of pressure over a predetermined
threshold. The gripping mechanism, e.g., deployment thereof from a
retracted configuration to a deployed configuration, may be
actuated via a command signal, e.g. an electrical signal.
[0075] The gripping mechanism may comprise at least one gripping
mechanism actuator capable of causing deployment of one or more
gripping elements. The at least one gripping mechanism actuator may
be coupled to and/or associated with one or more gripping
elements.
[0076] The gripping mechanism actuator may be automatically
operable and/or activated. Automatic activation of the gripping
mechanism actuator may be similar to the automatic activation
described above in respect of the first actuator and/or second
actuator, and is therefore not repeated here for reasons of
brevity.
[0077] The production apparatus is connectable to an emergency
disconnect package (EDP). The production apparatus may comprise an
EDP connector for connecting to the EDP. Advantageously, connecting
the EDP to the production apparatus, e.g. subsea tree, obviates the
need for a lower riser package (LRP) which would normally provide
the required emergency shearing/cutting and sealing
functionalities. This permits reduction in weight, cost and
complexity of the overall assembly, e.g. CWOR.
[0078] The production apparatus may be connectable to the EDP at or
near an upper portion thereof. The EDP connector may be provided at
or near an upper portion of the production apparatus.
[0079] In one embodiment, the CWOR assembly, e.g., EDP and/or
riser, may comprise a single bore. The assembly may comprise a bore
selector, e.g. provided within the EDP, for selective access to the
wellbore or to an annulus bore in the production apparatus, e.g.
for intervention operations in the subsea well.
[0080] In another embodiment, the CWOR assembly, e.g., EDP and/or
riser, may comprise a single bore for access to a single wellbore
in the production apparatus, e.g. for intervention operations in
the subsea well.
[0081] In another embodiment, the CWOR assembly, e.g., EDP and/or
riser, may comprise a two or more bores, e.g., a dual bore system,
one bore being configured for access to an annulus bore, and one
bore being configured for access to the wellbore in the production
apparatus, e.g. for intervention operations in the subsea well.
[0082] In one embodiment, actuation of the first wellbore valve
member and/or of the second wellbore valve member may cause the EDP
to disconnect from the production apparatus.
[0083] In another embodiment, disconnection of the EDP from the
production apparatus may be actuated by an emergency event, e.g. by
detection of pressure over a predetermined threshold. Disconnection
of the EDP from the production apparatus may be actuated by a
command signal, e.g., an electrical signal.
[0084] The CWOR assembly, e.g. the EDP and/or the production
apparatus, may comprise a disconnect actuator capable of causing
disconnection between the EDP and the production apparatus, e.g.
capable of causing disconnection of the EDP connector.
[0085] The disconnect actuator may be automatically operable and/or
activated. Automatic activation of the disconnect actuator may be
similar to the automatic activation described above in respect of
the first actuator and/or second actuator, and is therefore not
repeated here for reasons of brevity.
[0086] The production apparatus may further comprise an
intervention isolation device.
[0087] The intervention isolation device may comprise a valve,
e.g., a gate valve, flapper valve, ball valve, or the like.
[0088] The intervention isolation device may be axially spaced from
the first wellbore valve member, second wellbore valve member,
and/or wellbore valve, relative to the wellbore.
[0089] The intervention isolation device may be located above the
first wellbore valve member, second wellbore valve member, and/or
wellbore valve. The terms "above" and "up" will not be understood
to refer to any geometric arrangement, but will be understood to
refer to a location distal or away from the wellhead and/or
reservoir, whereas terms "below" and "down" will be understood to
refer to a location proximal to or nearer the wellhead and/or
reservoir.
[0090] The intervention isolation device may be provided at or near
an upper portion of the production apparatus.
[0091] Preferably, the intervention isolation device may be rated
to the maximum expected full shut-in wellbore conditions, e.g.,
maximum expected wellbore pressure. By such provision, closure of
the intervention isolation device may ensure protection of the
equipment above the intervention isolation device.
[0092] Typically, the intervention isolation device may be closed
during normal production operations, e.g., to produce hydrocarbons
from the reservoir, e.g., via a production line which may be in
fluid communication with the wellbore. The production line may be
connected to the wellbore within the production apparatus, e.g.,
below the intervention isolation device.
[0093] Typically, the intervention isolation device may provide
access to the well during intervention operations, e.g. to allow
deployment of a wireline, coiled tubing, etc.
[0094] The intervention isolation device may be associated with a
third actuator.
[0095] In normal operating conditions, the third actuator may be
operable by a user.
[0096] The intervention isolation device and/or third actuator may
be operated by a standard Remote Operating Vehicle (ROV).
[0097] The third actuator may be operable hydraulically,
electrically, or the like.
[0098] In an emergency situation, for example following detection
of pressure over a predetermined threshold, the third actuator may
be activated automatically. Automatic activation of the third
actuator may be similar to the automatic activation described above
in respect of the first actuator and/or second actuator.
[0099] Preferably, the first actuator, second actuator, and third
actuator may be operable automatically and independently of each
other.
[0100] The intervention isolation device may comprise a mechanical
plug having a locking profile in the wellbore. The mechanical plug
may be retrieved prior to intervention operations and/or may be
installed on completion of such operations by conventional well
interventions methods such as slickline, wireline or coiled
tubing.
[0101] The production apparatus may comprise and/or may be
associated with a pressure control device capable of controlling
and/or regulating pressure within a portion of the production
apparatus and/or downstream of the production apparatus.
[0102] The pressure control device may comprise a choke, e.g. a
subsea Christmas tree choke.
[0103] The pressure control device may comprise a production line
configured for allowing flow of fluid to and/or from the wellbore,
e.g., during production.
[0104] The production line may be in fluid communication with the
wellbore. The production line may be connected to the wellbore
within the production apparatus.
[0105] The production line may be connected to the wellbore at a
location below the intervention isolation device. By such
provision, when the intervention isolation device is closed, e.g.,
during normal production operations, the pressure control device
may be capable of controlling and/or regulating pressure and/or
flow of fluids flowing to and/or from the wellbore.
[0106] The production line may be connected to the wellbore at a
location above the first wellbore valve member, second wellbore
valve member, and/or wellbore valve. Because the first wellbore
valve member and second wellbore valve member are actuatable
independently of each other, e.g. automatically and independently
of each other, connecting the production line to the wellbore at a
location above the first wellbore valve member, second wellbore
valve member, and/or wellbore valve, obviates the need for
equipment located downstream of the pressure control device to be
rated to the maximum expected pressure which may in turn reduce
complexity of the production assembly and costs.
[0107] The production line may be connected to the wellbore at a
location between the intervention isolation device and the first
wellbore valve member, second wellbore valve member, and/or
wellbore valve.
[0108] The pressure control device may comprise at least one
pressure control valve rated to the maximum expected full shut-in
wellbore conditions, e.g. maximum expected wellbore pressure. By
such provision, closure of the pressure control valve may ensure
protection of the down-rated equipment downstream of the pressure
control device.
[0109] The production apparatus may comprise and/or may be
associated with a control system for automatically controlling
actuation and/or operation of the first wellbore valve member
and/or of the second wellbore valve member.
[0110] The control system may be configured for automatically
controlling actuation of the first wellbore valve member and the
second wellbore valve member.
[0111] The control system may be configured for automatically
operating the first actuator and/or the second actuator, preferably
both the first actuator and the second actuator.
[0112] The control system may be further configured for
automatically controlling actuation of the gripping mechanism. In
use, actuation of the gripping mechanism may be required only
during work-over mode, e.g., to catch any object entering the
wellbore. In such instance, the control system may comprise and/or
may be provided with a selective input allowing selective
enablement and/or disablement of the activation of the gripping
mechanism actuator.
[0113] In one embodiment, the control system may comprise and/or
may be provided with a work-over mode. When in work-over mode, the
gripping mechanism actuator may be activated and/or operated by the
control system. When not in work-over mode, the gripping mechanism
actuator may be not activated and/or operated. This may prevent
unnecessary actuation of the gripping mechanism during production
operation in event of an emergency.
[0114] In another embodiment, the control system may comprise
and/or may be provided with a production mode. When in production
mode, the gripping mechanism actuator may not be activated and/or
operated by the control system. When not in production mode, the
gripping mechanism actuator may be activated and/or operated. This
may prevent unnecessary actuation of the gripping mechanism during
production operation in event of an emergency.
[0115] The control system may comprise one or more sensors
configured to monitor and/or measure one or more predetermined
parameters, e.g. pressure, temperature, etc.
[0116] The one or more sensors may be located in the wellbore
and/or one or more conduits associated with and/or in fluid
communication with the wellbore.
[0117] Preferably, the control system may comprise a plurality of
sensors.
[0118] In one embodiment, the control system may comprise three or
more sensors.
[0119] Preferably, one or more sensors may be configured to monitor
and/or measure pressure.
[0120] In one embodiment, the control system may comprise one or
more control modules in communication with one or more sensors.
[0121] In another embodiment, the control system may comprise a
control module in communication with the plurality of sensors.
[0122] In an embodiment, the control system may comprise a
plurality of control modules, each control module being associated
and/or being in communication with a respective actuator. Each of
the first actuator, second actuator, third actuator, and/or
gripping mechanism actuator may be associated and/or may be in
communication with a respective control module. By such provision,
each actuator may be independently activated, thereby improving
safety and/or reliability.
[0123] In another embodiment, the control system may comprise a
control module associated and/or being in communication with a
plurality of actuators. The first actuator, second actuator, third
actuator, and/or gripping mechanism actuator may be associated
and/or may be in communication with the control module. By such
provision, simplicity of the control system may be improved. Such
an arrangement may also reduce the likelihood of an erroneous
shut-in occurring as a result of a control module failure.
[0124] The one or more sensors may be located downstream of the
pressure control device, first wellbore valve member and/or second
wellbore valve member. By such provision, detection of pressure
above a predetermined threshold by one or more sensors may cause
the control module to actuate the first wellbore valve member and
the second valve member.
[0125] In another embodiment, the one or more sensors may be
located upstream of the pressure control device. In such instance,
the one or more sensors may be located upstream of the first
wellbore valve member and/or second wellbore valve member, e.g.
below the production apparatus. Alternatively, the one or more
sensors may be located above of the first wellbore valve member
and/or second wellbore valve member, e.g. within or above the
production apparatus.
[0126] The control module(s) may be capable of receiving signals
from the sensors and of taking action upon analysis of the received
signals. The/each control module(s) may comprise a logic
solver.
[0127] In one embodiment, the control module(s), e.g. logic
solver(s), may initiate an action, e.g. actuation of one of more
actuators, when pressure above a predetermined threshold has been
detected by a predetermined number and/or ratio of the sensors. The
control module(s), e.g. logic solver(s), may initiate action, e.g.
actuation of one or more actuators, when pressure above a
predetermined threshold has been detected by a majority of sensors
associated with the control module, e.g. logic solver.
[0128] By way of example, when there are three pressure sensors,
the control module(s), e.g. logic solver(s), may initiate action,
e.g. actuation of one or more actuators, when pressure above a
predetermined threshold has been detected by at least two sensors.
Similarly, when there are five pressure sensors, the control
module(s), e.g. logic solver(s), may initiate action, e.g.
actuation of one or more actuators, when pressure above a
predetermined threshold has been detected by at least three
sensors. By such provision, in the event that one (three sensor
configuration) or two (five sensor configuration) of the sensors is
faulty, accidental activation may be avoided and/or required
activation may not be prevented.
[0129] A plurality of actuators, e.g. first actuator, second
actuator, and/or gripping mechanism actuator, may be in
communication with each other. By such provision, each actuator may
notify one or more other actuators upon activation. This may ensure
synchronisation of closure/activation and/or increased safety by
ensuring all synchronised actuators are activated should the
control module instruct activation of one of the synchronised
actuators.
[0130] The control module may comprise and/or may define a
so-called High Integrity Pressure Protection System (HIPPS).
[0131] According to a second aspect of the present invention there
is provided a production apparatus, the production apparatus
comprising:
[0132] a housing defining a wellbore;
[0133] a first wellbore valve member for closing the wellbore, the
first wellbore valve member provided within the housing, the first
wellbore valve member being coupled to a first actuator;
[0134] a second wellbore valve member for closing the wellbore, the
second wellbore valve member provided within the housing, the
second wellbore valve member being coupled to a second
actuator,
[0135] wherein the first wellbore actuator and the second wellbore
actuator each have at least two separate actuation mechanisms.
[0136] The first wellbore actuator and the second wellbore actuator
may each have two separate actuation mechanisms.
[0137] The first wellbore actuator may comprise a first actuation
mechanism and a second actuation mechanism.
[0138] The second wellbore actuator may comprise a first actuation
mechanism and a second actuation mechanism.
[0139] The first actuation mechanism of the first wellbore actuator
and the first actuation mechanism of the second wellbore actuator
may be the same or different.
[0140] The second actuation mechanism of the first wellbore
actuator and the second actuation mechanism of the second wellbore
actuator may be the same or different.
[0141] In an embodiment, the first actuation mechanism may comprise
an electric actuation mechanism. In another embodiment, the first
actuation mechanism may comprise a hydraulic actuation
mechanism.
[0142] The second actuation mechanism may comprise a mechanical
actuation mechanism, e.g. a spring. In an embodiment, the second
actuation mechanism may be activated upon loss of an activating
means to the first actuation mechanism, e.g. upon loss of
electrical power to the electric actuation mechanism, or upon loss
of hydraulic supply to the hydraulic actuation mechanism.
[0143] By such provision, the first and/or second actuator,
advantageously each of the first and second actuators, may be
provided with two separate actuation mechanisms which may help
ensure actuation of the first and/or second actuator in an
emergency, even in the event of a loss of electrical power and/or
hydraulic supply to the first actuation mechanism.
[0144] The production apparatus may comprise a control system for
automatically controlling actuation and/or operation of the first
wellbore valve member and/or of the second wellbore valve
member.
[0145] The control system may automatically control actuation of
the first wellbore valve member and the second wellbore valve
member.
[0146] The control system may control actuation of the first
wellbore valve member and the second wellbore valve member
independently of each other.
[0147] The control system may comprise one or more control module
in communication with one or more sensors. The control module may
comprise and/or may define a High Integrity Pressure Protection
System (HIPPS).
[0148] The features described in connection with the production
apparatus according the first aspect of the invention may apply to
the production apparatus according to the second aspect of the
invention, and are therefore not repeated here for brevity.
[0149] According to a third aspect of the present invention there
is provided a production apparatus, the production apparatus
comprising:
[0150] a housing defining a wellbore;
[0151] a first wellbore valve member for closing the wellbore, the
first wellbore valve member provided within the housing, the first
wellbore valve member being capable, in use, of shearing an object
located in the wellbore; and
[0152] a second wellbore valve member for closing the wellbore, the
second wellbore valve member provided within the housing, the
second wellbore valve member being capable, in use, of shearing an
object located in the wellbore; and
[0153] a gripping mechanism disposed within the housing and
configured for gripping and/or catching the object within the
wellbore.
[0154] The gripping mechanism may be located below the first
wellbore valve member and the second wellbore valve member. By such
provision, upon actuation of the first wellbore valve member and/or
the second wellbore valve member, causing the object, e.g. a
tubular, to be severed, the gripping mechanism may prevent the
severed object from falling down the wellbore.
[0155] It will be understood that gripping and/or catching an
object, e.g., a tubular, located in the wellbore, may be required
in workover mode, e.g. during intervention operations, when an
object such as a tubular is or has been inserted in the wellbore to
perform a given intervention task, and closure of the first
wellbore valve member and/or the second wellbore valve member
causes shearing of the tubular. However, during normal production
operations, a tubular would typically not be present in the
wellbore, and actuation of a/the gripping mechanism would therefore
not be necessary.
[0156] The gripping mechanism may comprise a plurality of gripping
elements, and at least one gripping mechanism actuator coupled to
and/or associated with one or more gripping elements.
[0157] The features described in connection with the production
apparatus according to the first aspect or the second aspect of the
invention may apply to the production apparatus according to the
third aspect of the invention, and are therefore not repeated for
brevity.
[0158] According to a fourth aspect of the present invention there
is provided a subsea assembly comprising a production apparatus
according to any of the first, second, or third aspect of the
invention.
[0159] The subsea assembly may define a Completion Work-Over Riser
(CWOR) assembly.
[0160] The assembly may comprise an emergency disconnect package
(EDP).
[0161] The assembly may comprise an EDP connector for connecting
the EDP to the production apparatus. Advantageously, connecting the
EDP directly to the production apparatus, e.g. subsea tree,
obviates the need for a lower riser package (LRP) which would
normally provide the required emergency shearing/cutting and
sealing functionalities. This permits reduction in weight, cost and
complexity of the overall assembly, e.g. CWOR.
[0162] The EDP connector may be provided on or may form part of the
EDP.
[0163] The EDP connector may be provided on or may form part of the
production apparatus.
[0164] The EDP connector may comprise two connector portions, a
first connector portion being provided on or forming part of the
production apparatus, and a second connector portion being provided
on or forming part of the EDP.
[0165] The assembly may comprise a/the control system for
automatically controlling actuation and/or operation of the first
wellbore valve member and/or of the second wellbore valve
member.
[0166] According to a fifth aspect of the present invention there
is provided a method for closing a wellbore in a production
apparatus, the method comprising:
[0167] providing a production apparatus configured to be connected
to an emergency disconnect package (EDP), the production apparatus
comprising a housing defining a wellbore; a first wellbore valve
member for closing the wellbore, the first wellbore valve member
provided within the housing, the first wellbore valve member being
capable, in use, of shearing an object located in the wellbore; and
a second wellbore valve member for closing the wellbore, the second
wellbore valve member provided within the housing, the second
wellbore valve member being capable, in use, of shearing an object
located in the wellbore; and
[0168] actuating and/or operating the first wellbore valve member
and the second wellbore valve member.
[0169] The method may comprise actuating and/or operating the first
wellbore valve member and the second wellbore valve member
independently of each other.
[0170] The method may comprise actuating and/or operating the first
wellbore valve member and the second wellbore valve member
automatically.
[0171] The method may comprise shearing an object, e.g. a tubular,
located in the wellbore. It will be understood that shearing an
object, e.g. a tubular, located in the wellbore, may be required in
workover mode, e.g. during intervention operations, when an object
such as a tubular is or has been inserted in the wellbore to
perform a given intervention task. However, during normal
production operations, a tubular would typically not be present in
the wellbore, and the method would therefore not involve shearing
such a tubular.
[0172] The method may comprise shearing the object during actuation
and/or operation of the first wellbore valve member and/or of the
second wellbore valve member.
[0173] The method may comprise catching the object, e.g., the
tubular. The method may comprise catching the object within or
inside the production apparatus.
[0174] The method may comprise catching the object, e.g. the
tubular, below the first wellbore valve member and the second
wellbore valve member. By such provision, upon actuation of the
first wellbore valve member and/or the second wellbore valve
member, causing the object, e.g. a tubular, to be severed, the
gripping mechanism may prevent the severed object from falling down
the wellbore.
[0175] The method may comprise automatically catching the object,
e.g. the tubular. The method may comprise automatically controlling
actuation of a/the gripping mechanism.
[0176] The method may comprise disconnecting the production
apparatus from an emergency disconnect package (EDP) which may be
directly connected to the production apparatus.
[0177] The method may comprise automatically controlling actuation
and/or operation of the first wellbore valve member and/or of the
second wellbore valve member, e.g. by using a control system.
[0178] The method may comprise monitoring and/or measuring one or
more predetermined parameters, e.g. pressure, temperature, etc. The
method may comprise monitoring and/or measuring one or more
predetermined parameters in the wellbore and/or in one or more
conduits associated with and/or in fluid communication with the
wellbore.
[0179] Preferably, the method may comprise monitoring and/or
measuring pressure in the wellbore and/or in one or more conduits
associated with and/or in fluid communication with the
wellbore.
[0180] The method may comprise monitoring and/or measuring pressure
using a plurality of sensors.
[0181] The method may comprise monitoring and/or measuring pressure
downstream of the first wellbore valve member and/or second
wellbore valve member. By such provision, detection of pressure
above a predetermined threshold by one or more sensors may cause
the control module to actuate and/or operate the first wellbore
valve member and the second valve member.
[0182] The method may comprise monitoring and/or measuring pressure
upstream of the first wellbore valve member and/or second wellbore
valve member, e.g. below or within the production apparatus.
[0183] The method may comprise processing signals and/or
information received from one or more sensors using one or more
control module in communication with one or more sensors.
[0184] The method may comprise actuating the first wellbore valve
member, the second wellbore valve member, and/or the gripping
mechanism, for example by activating or operating a/the first
wellbore valve member actuator, a/the second wellbore valve member
actuator, and/or the gripping mechanism actuator, when pressure
above a predetermined threshold has been detected by one or more
sensors, e.g. by a predetermined number and/or ratio of
sensors.
[0185] Following closure of the wellbore, the method may comprise
resuming production. The method for resuming production may be
carried out when pressure measured and/or monitored by one or more
sensors is within a predetermined limit.
[0186] The method for resuming production may comprise closing
the/a pressure control device.
[0187] The method may comprise opening the first wellbore valve
member, and/or second wellbore valve member actuator, preferably
both the first wellbore valve member and the second wellbore valve
member actuator.
[0188] In the event that the production apparatus comprises a
gripping mechanism, and that the gripping mechanism has been
activated, for example in workover mode, the method may comprise
opening the gripping mechanism.
[0189] The method may comprise opening the pressure control device,
for example until a new set-point is reached in a portion of the
downstream equipment, e.g. within the predetermined limit.
[0190] Advantageously, following a safety event, e.g. emergency
closure of the wellbore, the systems and methods of the present
invention may allow the system to be rendered operational again for
production quickly after such a safety event.
[0191] The features described in connection with the production
apparatus according the first, second or third aspect of the
invention or the assembly according to the fourth aspect of the
invention may apply to the method according to the fifth aspect of
the invention, and are therefore not repeated for brevity.
[0192] According to a sixth aspect of the present invention there
is provided a method for resuming production following a safety
event, the method comprising, in sequence:
[0193] closing the/a pressure control device;
[0194] opening a first wellbore valve member and a second wellbore
valve member, the first wellbore valve member and the second
wellbore valve member being configured for closing a wellbore and
being capable, in use, of shearing an object located in the
wellbore, the first wellbore valve member and the second wellbore
being provided within a housing of a production apparatus
connectable to an emergency disconnect package (EDP).
[0195] In the event that the production apparatus comprises a
gripping mechanism, and that the gripping mechanism has been
activated, for example in workover mode, the method may comprise
deployment of a retrieval tool to secure the sheared object,
opening the gripping mechanism and retrieving the sheared
object.
[0196] The method may comprise opening the pressure control device,
for example until a new set-point is reached in a portion of the
downstream equipment, e.g. within the predetermined limit.
[0197] The features described in connection with the production
apparatus according to the first, second or third aspect of the
invention, with the assembly according to the fourth aspect of the
invention, or with the method according to a fifth aspect of the
invention may apply to the method according to the sixth aspect of
the invention, and are therefore not repeated for brevity.
BRIEF DESCRIPTION OF DRAWINGS
[0198] Embodiments of the invention will now be given by way of
example only, and with reference to the accompanying drawings,
which are:
[0199] FIG. 1 a schematic view of a prior art CWOR assembly;
[0200] FIG. 2 a cross-sectional view of a prior art CWOR
assembly;
[0201] FIG. 3 a cross-sectional view of an improved CWOR assembly
according to a first embodiment of the present invention;
[0202] FIG. 3A an enlarged portion of the assembly of FIG. 3;
[0203] FIG. 4 a cross-sectional view of a CWOR assembly according
to a second embodiment of the present invention;
[0204] FIG. 4A an enlarged portion of the assembly of FIG. 4;
[0205] FIG. 5 a cross-sectional view of a CWOR assembly according
to a third embodiment of the present invention;
[0206] FIG. 5A an enlarged portion of the assembly of FIG. 5;
[0207] FIG. 6 a cross-sectional view of a CWOR assembly according
to a fourth embodiment of the present invention;
[0208] FIG. 6A an enlarged portion of the assembly of FIG. 6;
[0209] FIG. 7 a cross-sectional view of a CWOR assembly according
to a fifth embodiment of the present invention;
[0210] FIG. 7A an enlarged portion of the assembly of FIG. 7;
[0211] FIG. 8 a schematic view of a CWOR assembly according to a
sixth embodiment of the present invention;
[0212] FIG. 9 a schematic view of an alternative embodiment of the
control system used in assembly of FIG. 7 or FIG. 8;
[0213] FIGS. 10a and 10b elevated perspective views of an actuator
used in the assembly of FIG. 8 or FIG. 9; and
[0214] FIG. 10c a cutaway perspective view an actuator used in the
assembly of FIG. 8 or FIG. 9; and
[0215] FIG. 11 a schematic view of an alternative embodiment of the
CWOR assembly of FIG. 8.
DETAILED DESCRIPTION OF DRAWINGS
[0216] Referring to FIG. 1 there is shown a schematic view of a
prior art CWOR assembly, generally designated 5, according to the
prior art.
[0217] The assembly 5 comprises a wellhead 10, a production
apparatus 20 in the form of a Christmas tree and connected on top
of the wellhead 10 located on the seabed, a Lower Riser Package
(LRP) 40, an emergency disconnect package (EDP) 35, and a riser
30.
[0218] The riser 30 has a pressure-containing tubular 31 that
provides a pressure containment system from subsea to surface.
[0219] The emergency disconnect package (EDP) 35 is attached to the
riser 30 and is connectable to a Lower Riser Package (LRP) 40. The
emergency disconnect package (EDP) 35 is capable of disconnecting
from the LRP 40 in the event of an emergency. The EDP 35 has a
riser valve 32 to prevent discharge of fluids, e.g. hydrocarbons,
from the riser 30 as a result of disconnection of the EDP 35.
[0220] The LRP 40 has two safety valves 41,42 capable of shearing
and sealing the wellbore, essentially replicating the functions of
a blowout preventer (BOP) stack as used during well drilling and
completion operations. The LRP 40 also has a connecting portion 43
for connecting to the Christmas tree 20.
[0221] The Christmas tree 20 includes a lower master valve 21 and
an upper master 22 to control the flow of fluids through the
wellbore. The Christmas tree 20 also includes a wing valve 23 and a
choke valve 24 to control, during production, pressure within the
wellbore and flow of fluids from the wellbore to surface via a flow
line 25.
[0222] Referring now to FIG. 2 there is shown a cross-sectional
view of a prior art CWOR assembly, generally designated 5'. The
assembly 5' is generally similar to the assembly 5 of FIG. 1, like
parts being denoted by like numerals, but with a prime symbol
"'".
[0223] The assembly 5' has a main bore 51' and an annulus bore 52'
in communication with the subsea well.
[0224] The assembly 5' also includes a wellhead 10', and a tubing
hanger 11'. A subsea production apparatus 20' in the form of a
Christmas tree is connected to the wellhead 10' via wellhead
connector 26'.
[0225] The assembly 5' includes an emergency disconnect package
(EDP) 35' attached to a lower end of a riser (not shown) and
connected to a Lower Riser Package (LRP) 40' and capable of
disconnecting from the LRP 40' in the event of an emergency. The
EDP 35' has a main riser valve 32' to prevent discharge of fluids,
e.g. hydrocarbons, from the main bore 51' of the riser as a result
of disconnection of the EDP 35'. The EDP 35' includes an annulus
riser valve 32a' to prevent discharge of fluids, e.g. hydrocarbons,
from the annulus bore 52' of the riser as a result of disconnection
of the EDP 35'.
[0226] The LRP 40' includes safety valves 41',42' capable of
shearing through and sealing the main bore 51'. The LRP 40' also
has safety valves 41a',42a' capable of shearing through and sealing
the annulus bore 52'. Valves 41',41a' may be the same or different.
Valves 42',42a' may be the same or different.
[0227] The LRP 40' is connected to the Christmas tree 20' via tree
connector 43'.
[0228] The Christmas tree 20' includes a lower master valve 21' and
an upper master 22' to control the flow of fluids through the main
bore 51'. The Christmas tree 20' also has an annulus master valve
21a' to control the flow of fluids through the annulus bore
52'.
[0229] The Christmas tree 20' has an intervention isolation valve
or swab valve 27'. The swab valve 27' is provided near an upper end
of the Christmas tree 20'. Typically, the swab valve 27' is closed
during normal production operations, and can be opened to provide
access to the main bore 51' during intervention operations, e.g. to
allow deployment of a wireline, coiled tubing, etc.
[0230] The Christmas tree 20' also includes an annulus intervention
isolation valve 27a' or annulus swab valve. The annulus swab valve
27a' is provided near an upper end of the Christmas tree 20'. The
annulus swab valve 27a' is configured to provide access to the
annulus bore 52' during intervention operations.
[0231] The Christmas tree 20' also has a wing valve 23' and a choke
valve 24' to control, during production, pressure within the main
bore 51' and flow of fluid from the main bore 51' to surface via a
main flow line 25'.
[0232] The Christmas tree 20' also has an annulus isolation valve
23a' to control pressure within the annulus bore 52' and flow of
fluid between the annulus bore 51' and surface via an annulus flow
line 25a'.
[0233] Referring now to FIG. 3 there is shown a cross-sectional
view of a production assembly 105 according to a first embodiment
of the present invention. Parts of the assembly 105 of FIG. 3
corresponding to similar parts of the assemblies 5 or 5' of FIGS. 1
and 2 and are denoted by like numerals, but incremented by 100.
[0234] In the embodiment of FIG. 3, the assembly 105 has a housing
190 that defines a main bore 151 and an annulus bore 152 in
communication with the subsea well.
[0235] The assembly 105 comprises a subsea production apparatus 120
in the form of a Christmas tree connected to a wellhead 110 via
wellhead connector 126.
[0236] The assembly 105 includes an emergency disconnect package
(EDP) 135 attached to a lower end of a riser (not shown).
[0237] The assembly EDP 135 is connected directly to the Christmas
tree 120. The EDP 135 is capable of disconnecting from the
Christmas tree 120 via disconnector 136 in the event of an
emergency. The EDP 135 has a main riser valve 132 to prevent
discharge of fluids, e.g. hydrocarbons, from the main bore 151 of
the riser as a result of disconnection of the EDP 135. The EDP 135
also has an annulus riser valve 132a to prevent discharge of
fluids, e.g. hydrocarbons, from the annulus bore 152 of the riser
as a result of disconnection of the EDP 135.
[0238] The Christmas tree 120 has an annulus master valve 121a to
control the flow of fluids through the annulus bore 152.
[0239] The Christmas tree 120 has a wellbore valve 160 having a
first wellbore valve member 161 or first gate, and a second
wellbore valve member 162 or second gate (as best shown in FIG. 3A
showing an enlarged portion of FIG. 3). In an open configuration,
the first gate 161 and second gate 162 allow flow of fluids through
the main bore 151. In a closed configuration, the first gate 161
and second gate 162 prevent flow of fluids through the main bore
151.
[0240] In use, each of the first gate 161 and the second gate 162
has a shearing face and is capable of shearing an object, e.g. a
tubular, located between the first 161 and second 162 gates within
the main bore 151. For example, the wellbore valve 160 has a valve
as marketed by Enovate Systems Ltd under the trade name
En-Tegrity.
[0241] The first gate 161 and the second gate 162 are rated to the
maximum expected full shut-in wellbore conditions, e.g. maximum
expected wellbore pressure. By such provision, closure of one or
both of the first gate 161 and the second gate 162 protects the
equipment above and/or downstream of the wellbore valve 160.
[0242] In this embodiment, the first gate 161 and the second gate
162 are operable automatically and independently of each other.
This ensures compliance with the provision of two independent
failsafe barriers, as required by API Standards. This also obviates
the need for a separate LRP to be provided between the EDP 135 and
the Christmas tree 120 to ensure well isolation in case of an
emergency. This also obviates the need for equipment located
downstream of the production apparatus to be rated to the maximum
expected pressure. This allows reduction in the size and weight of
the subsea assembly, thus reducing manufacturing costs, whilst
reducing the complexity of the CWOR assembly 105 and being more
easily deployable from a wider range of vessels.
[0243] The Christmas tree 120 includes an intervention isolation
valve 127. The intervention isolation valve 127 is provided near an
upper end of the Christmas tree 120'. Typically, the intervention
isolation valve 127 is closed during normal production operations,
and is opened to provide access to the main bore 151 during
intervention operations, e.g. to allow deployment of a wireline,
coiled tubing, etc.
[0244] The Christmas tree 120 also has an annulus intervention
isolation valve 127a. The annulus intervention isolation valve 127a
is provided near an upper end of the Christmas tree 120. The
annulus intervention isolation valve 127a provides access to the
annulus bore 152 during intervention operations.
[0245] The Christmas tree 120 also has a wing valve 123 and a choke
valve 124 to control, during production, pressure within the main
bore 151 and flow of fluid from the main bore 151 to surface via a
main flow line 125.
[0246] The Christmas tree 120 also has an annulus isolation valve
123a to control pressure within the annulus bore 152 and flow of
fluid between the annulus bore 152 and surface via an annulus flow
line 125a.
[0247] FIG. 4 shows a cross-sectional view of a production assembly
205 according to a second embodiment of the present invention. The
assembly 205 of FIG. 4 is generally similar to the assembly 105 of
FIG. 3, like parts being denoted by like numerals, but incremented
by 100.
[0248] In the embodiment of FIG. 4, the assembly 205 has a single
main bore 251 extending through an upper portion of the Christmas
tree 220 and the EDP 235, rather than a main bore 151 and an
annulus bore 152 as shown in the embodiment of FIG. 3. The
provision of a single bore 251 through an upper portion of the
Christmas tree 220 and the EDP 235 is sufficient when access to the
main bore 251 from surface is required, but access to a well
annulus bore from surface is not required.
[0249] The EDP 235 also has a crossover line 238 equipped with a
crossover valve 239. The crossover line is in fluid communication
with main bore 251. The crossover line 238 is also in fluid
communication with the annulus bore 252. The purpose of the
crossover line is to allow communication between main bore 251 and
annulus bore 252 to equalise pressure if and when required.
[0250] FIG. 5 shows a cross-sectional view of a production assembly
305 according to a third embodiment of the present invention. The
assembly 305 of FIG. 5 is generally similar to the assembly 105 of
FIG. 3, like parts being denoted by like numerals, but incremented
by 200.
[0251] In the embodiment of FIG. 5, the assembly 305 includes a
main bore 351 and an annulus bore 352 through the Christmas tree
320. However, in the embodiment of FIG. 5, the EDP comprises a bore
selector 337 to allow selective communication between an upper
single bore 338 and either the main bore 351 or the annulus bore
352. The provision of a single upper bore 338 simplifies
construction and reduces costs associated with the riser, but also
allows selective access to either the main bore 351 or the annulus
bore 352.
[0252] FIG. 6 shows a cross-sectional view of a production assembly
405 according to a fourth embodiment of the present invention. The
assembly 405 of FIG. 6 is generally similar to the assembly 205 of
FIG. 4, like parts being denoted by like numerals, but incremented
by 200.
[0253] In the embodiment of FIG. 6, the assembly 405 has a gripping
mechanism 465 configured for gripping and/or catching an object,
e.g., a tubular, within the wellbore 451.
[0254] The gripping mechanism 465 is moveable between a retracted,
non-engaged configuration (as shown in FIG. 6) and a deployed,
engaged configuration (now shown in the interest of clarity) in
which the gripping mechanism 465 applies a gripping force to the
object.
[0255] The gripping mechanism 465 is located below the wellbore
valve 460. By such provision, upon actuation of the wellbore valve
460, e.g. of the first gate 461 and/or of the second gate 462 (as
best shown in FIG. 6A showing an enlarged portion of FIG. 6), the
gripping mechanism 465 is used to prevent a severed object from
falling down the wellbore 451.
[0256] FIG. 7 shows a cross-sectional view of a production assembly
505 according to a fifth embodiment of the present invention. The
assembly 505 of FIG. 7 is generally similar to the assembly 405 of
FIG. 6, like parts being denoted by like numerals, but incremented
by 100.
[0257] In the embodiment of FIG. 7, the assembly 505 includes
control system 570 for automatically controlling actuation and/or
operation of a wellbore valve 560. In this embodiment, the control
system controls automatically and independently actuation and/or
operation of a first gate 561 and a second gate 562.
[0258] This ensures compliance with the provision of two
independent failsafe barriers which will close the wellbore 551
automatically in the event of an emergency, as required by API
Standards. This also obviates the need for a separate LRP to be
provided between the EDP 535 and the Christmas tree 520 to ensure
well isolation in such an event.
[0259] The control system 570 is configured for automatically
operating a first actuator (not shown) connected to the first gate
561 and a second actuator (not shown) connected to the second gate
562. The actuators are described in more detail in connection with
the embodiment of FIG. 8.
[0260] In other embodiments, the control system 570 may be further
configured to automatically control actuation of the gripping
mechanism 565.
[0261] The control system has a control module 574 coupled to a
plurality of pressure sensors 571,572,573 configured to monitor
and/or measure pressure at a portion of the main flow line 525. In
this embodiment, the sensors 571,572,573 are conveniently located
downstream of the wellbore valve 560 and downstream of the choke
valve 524, which may help ease of installation and/or
maintenance.
[0262] In operation, detection of pressure above a predetermined
threshold by one or more of the sensors 571,572,573 is fed to the
module 574 which will then cause the control module 574 to actuate
the first gate 561 and the second gate 562.
[0263] The control module 574 receives signals from the sensors
571,572,573 and takes action, e.g., initiates closure of the first
gate 561 and the second gate 562, upon analysis of the received
signals.
[0264] Typically, the control module 574 comprises one or more
logic solvers. In this embodiment, the logic solver(s) of the
control module 574 initiate closure of first gate 561 and second
gate 562, e.g. activation of a first actuator and second actuator
associated therewith, when pressure above a predetermined threshold
has been measured by at least two out of the three sensors
571,572,573. By such provision, in the event that one of the
sensors 571,572,573 is faulty, accidental activation is avoided in
the event that one of the sensors 571,572,573 incorrectly detects
high pressure under otherwise normal pressure conditions, and/or
necessary activation is not prevented in the event that one of the
sensors 571,572,573 does not detect an abnormally high pressure
above the predetermined threshold.
[0265] The choke valve 524 is rated to the maximum expected full
shut-in wellbore conditions, e.g. maximum expected wellbore
pressure. By such provision, closure of the choke valve 524 ensures
protection of the down-rated equipment downstream of the choke
valve 524.
[0266] The intervention isolation valve 527 is also rated to the
maximum expected full shut-in wellbore conditions, e.g., maximum
expected wellbore pressure. By such provision, closure of the
intervention isolation valve 527 ensures protection of the
equipment above the intervention isolation valve 127.
[0267] By the arrangement depicted in FIG. 7, the equipment
required to be rated to the maximum expected full shut-in wellbore
conditions is confined below the intervention isolation valves 527
of the Christmas tree 520 and upstream of the choke valve 524, thus
reducing costs, weight, and complexity of the assembly 505.
[0268] FIG. 8 shows a schematic view of a production assembly 605
according to a sixth embodiment of the present invention. The
assembly 605 of FIG. 8 is generally similar to the assembly 505 of
FIG. 7, like parts being denoted by like numerals, but incremented
by 100.
[0269] FIG. 8 depicts the well 612 between reservoir 613 and
wellhead 610.
[0270] In the embodiment of FIG. 8, the Christmas tree 620 has two
intervention isolation valves 628,629 at an upper portion thereof.
The intervention isolation valves 628,629 are configured to provide
access to the wellbore 651 during intervention operations.
[0271] FIG. 8 depicts a first actuator 681 configured to actuate
first gate 661, second actuator 682 configured to actuate second
gate 662, and third actuator 686 configured to actuate gripping
mechanism 665.
[0272] In this embodiment, each of the first, second, and third
actuators 681,682,686 is associated with a respective control
module including a logic solver 683,684,687 respectively. Each
logic solver 683,684,687 receives signals 688 from sensors
671,672,673 and is capable of taking action, e.g. initiate
actuation of closure of the first, second, and third actuators
681,682,686, upon analysis of the received signals 688.
[0273] In this embodiment, there is provided a workover mode input
689. If workover mode is activated, actuation of the gripping
mechanism 665 is enabled. The logic solver 686 is enabled to
activate third actuator 687 when pressure sensors 671,672,673
detect pressure above a predetermined threshold. However, if
workover mode is not activated, actuation of the gripping mechanism
665 is disabled, i.e., logic solver 686 is not enabled to activate
third actuator 687 when pressure is above a predetermined
threshold. This ensures that, when not in workover mode, i.e. when
no object such as a tubular is present in the wellbore 651, the
gripping mechanism 665 is not unnecessarily actuated.
[0274] The assembly 605 also includes an isolation valve 691 and a
production wing valve 623 to permit testing of the control system
670. When testing is desired, the first isolation valves 691 and
the wing valve 623 are closed, thereby isolating a portion 693 of
flow line 625 containing pressure sensors 671,672,673 between wing
valve 623 and isolation valve. A service line valve 692 is also
provided to control flow from service line 694 into portion 693. In
order to create an over-pressure event, service line valve 692 is
opened to inject a fluid and increase pressure within the section
693. Pressure is increased to a desired level, until pressure
sensors 671,672,673 reach the predetermined threshold at which the
logic solvers 683,684,687 activate actuators 681,682,686. By such
provision, the efficacy of the failsafe system may be efficiently
and quickly tested.
[0275] Following a safety event, production may be resumed quickly
and efficiently using the assembly 605.
[0276] Once pressure measured by sensors 671,672,673 is below a
predetermined threshold, production may be resumed by performing
the following steps, in sequence: [0277] closing the pressure
control device comprising choke valve 624; [0278] opening the first
gate 661 and second gate 662; [0279] in the event that the gripping
mechanism 665 has been activated deploying a retrieval tool and
securing the sheared object; [0280] in the event that the gripping
mechanism 665 has been activated, opening the gripping mechanism
665; [0281] retrieval of the sheared object using the retrieval
tool; [0282] opening wing valve 623; and [0283] opening the
pressure control device comprising choke valve 624 until a desired
pressure new set-point is reached in portion of the flow line 693
comprising pressure sensors 671,672,673.
[0284] FIG. 9 is a schematic view of an alternative embodiment of
the control system used in the assembly of FIG. 7, like parts being
denoted by like numerals, but incremented by 200.
[0285] The control system 770 has a control module 774 for
automatically operating a first actuator 781 connected to a first
gate 761 and a second actuator 782 connected to a second gate 762.
The control module 774 receives signals 788 from pressure sensors
771,772,773.
[0286] In operation, detection of pressure above a predetermined
threshold by one or more of the sensors 771,772,773 is fed to the
module 774 which will then cause the control module 774 to actuate
the first gate 761 and the second gate 762.
[0287] The control module 774 receives signals from the sensors
771,772,773 and takes action, e.g., initiates closure of the first
gate 761 and the second gate 762, upon analysis of the received
signals.
[0288] Typically, the control module 774 comprises one or more
logic solvers. In this embodiment, the logic solver(s) of the
control module 774 initiate closure of first gate 761 and second
gate 762, i.e. activation of the first actuator 781 and second
actuator 782 associated therewith, when pressure above a
predetermined threshold has been measured by at least two out of
the three sensors 771,772,773. By such provision, in the event that
one of the sensors 771,772,773 is faulty, accidental activation is
avoided in the event that one of the sensors 771,772,773
incorrectly detects high pressure under otherwise normal pressure
conditions, and/or necessary activation is not prevented in the
event that one of the sensors 771,772,773 does not detect an
abnormally high pressure above the predetermined threshold.
[0289] FIGS. 10a, 10b and 10c depict an actuator 1001 that may be
used as actuator 681, 682 and/or 683 of FIG. 8, or as actuator 781
and/or 782 of FIG. 9.
[0290] The actuator 1001 comprises an electric drive 1003
containing both an electric drive mechanism and control electronics
used to operate an actuator member 1002. The electric drive 1003 is
configured to compress a spring 1005 in a spring chamber 1004.
During initialisation of the actuator 1001, the spring 1005 is
compressed and mechanically latched in position by latch 1006.
Following initialisation the electric drive 1003 may be used to
open and close valve gates (not shown) in normal using non-fail
safe control methods while the spring 1005 may remain compressed. A
latch release mechanism 1007 consisting of a hammer held by a
continuously powered solenoid is released on loss of electrical
power to the solenoid, e.g., in an emergency situation such as main
electrical power failure. The latch release 1007 disengages the
mechanical latch 1006 and releases the spring 1005 to operate the
actuator 1001 and close the valve gate.
[0291] FIG. 11 depicts an alternative embodiment 805 of the CWOR
assembly 605 of FIG. 8. The assembly 805 of FIG. 11 is generally
similar to the assembly 605 of FIG. 8, like parts being denoted by
like numerals, but incremented by 200.
[0292] However, in this embodiment, the CWOR assembly 805 includes
an upper tree 806 and a lower tree 807. Thus, in this embodiment,
the Christmas tree includes two complementary and connected parts
consisting of the upper tree 806 and the lower tree 807.
[0293] The upper tree 806 includes the pressure regulating means
and control system 870 as described in connection with FIG. 8.
However, in this embodiment, the first actuator 881 configured to
actuate the first gate 861, the second actuator 882 configured to
actuate the second gate 862, and the third actuator 886 configured
to actuate the gripping mechanism 865 in workover mode are all
provided within the lower tree 807.
[0294] In this embodiment the lower tree 806 is in the form of a
tubing head spool.
[0295] By such an arrangement the first gate 861, second gate 862,
and gripping mechanism 865 can be confined to the tubing head spool
806, with the upper tree 807 being disposed on top of the tubing
head spool 806.
[0296] The upper tree 806 has two intervention isolation valves
828,829 at an upper portion thereof. The intervention isolation
valves 828,829 are configured to provide access to the wellbore 851
during intervention operations.
[0297] In the embodiments shown in FIGS. 7, 8, 9 and 11, the
control system 570,670,770,870 comprises three sensors 571,572,573;
671,672,673; 771,772,773, 871,872,873. However, it will be
appreciated that, in other embodiments, the control system may
comprise any number of sensors depending on the requirements of the
system.
* * * * *