U.S. patent application number 11/721871 was filed with the patent office on 2008-10-30 for modular actuator for subsea valves and equipment, and methods of using same.
Invention is credited to John A. Johansen, Vidar Sten-Halvorsen.
Application Number | 20080264646 11/721871 |
Document ID | / |
Family ID | 35238021 |
Filed Date | 2008-10-30 |
United States Patent
Application |
20080264646 |
Kind Code |
A1 |
Sten-Halvorsen; Vidar ; et
al. |
October 30, 2008 |
Modular Actuator for Subsea Valves and Equipment, and Methods of
Using Same
Abstract
The present invention is directed to a modular actuator for
subsea valves and equipment, and various methods of using same. In
one illustrative embodiment, the actuator includes a hydraulic
actuator, at least one housing and a self-contained hydraulic
supply system positioned within the at least one housing.
Inventors: |
Sten-Halvorsen; Vidar;
(Kongsberg, NO) ; Johansen; John A.; (Kongsberg,
NO) |
Correspondence
Address: |
WILLIAMS, MORGAN & AMERSON
10333 RICHMOND, SUITE 1100
HOUSTON
TX
77042
US
|
Family ID: |
35238021 |
Appl. No.: |
11/721871 |
Filed: |
December 13, 2005 |
PCT Filed: |
December 13, 2005 |
PCT NO: |
PCT/US05/44997 |
371 Date: |
February 18, 2008 |
Current U.S.
Class: |
166/360 ;
166/319; 166/368 |
Current CPC
Class: |
E21B 33/0355 20130101;
E21B 34/04 20130101 |
Class at
Publication: |
166/360 ;
166/368; 166/319 |
International
Class: |
E21B 33/035 20060101
E21B033/035; E21B 34/04 20060101 E21B034/04 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 22, 2004 |
NO |
20045600 |
Claims
1. A modular actuator adapted to be releasably coupled to a subsea
device, comprising: a hydraulic actuator; at least one housing; and
a self-contained hydraulic supply system positioned within said at
least one housing.
2. The modular actuator of claim 1, wherein said subsea device
comprises a valve.
3. The modular actuator of claim 1, wherein said subsea device
comprises a Christmas tree.
4. The modular actuator of claim 1, further comprising a control
system positioned within said at least one housing to control
delivery of a high pressure hydraulic fluid produced by said
self-contained hydraulic supply system.
5. The modular actuator of claim 1, further comprising a
self-contained source of electrical power positioned within said at
least one housing, wherein said self-contained source of electrical
power is the primary source of electrical power for said modular
actuator.
6. The modular actuator of claim 5, wherein said self-contained
source of electrical power comprises at least one battery.
7. The modular actuator of claim 1, wherein said self-contained
hydraulic supply system comprises a pressure intensifier.
8. The modular actuator of claim 1, wherein said self-contained
hydraulic system positioned within said housing comprises a pump
driven by an electrical motor.
9. The modular actuator of claim 1, wherein said self-contained
hydraulic system comprises at least one fluid reservoir and a
control/vent valve.
10. The modular actuator of claim 1, wherein said modular actuator
further comprises means for releasably coupling said modular
actuator to said subsea device.
11. The modular actuator of claim 2, wherein said self-contained
hydraulic supply system is adapted to supply a pressurized fluid
employed in actuating said subsea valve.
12. The modular actuator of claim 3, wherein said self-contained
hydraulic supply system is adapted to supply a pressurized fluid
employed in actuating a valve within said Christmas tree.
13. The modular actuator of claim 1, wherein said modular actuator
is adapted to be releasably coupled to said subsea device by an
ROV.
14. A modular actuator adapted to be releasably coupled to a subsea
device, comprising: a hydraulic actuator; at least one housing; and
a plurality of components positioned within said at least one
housing, said components comprising: a self-contained hydraulic
supply system; and a control system to control delivery of a high
pressure hydraulic fluid produced by said self-contained hydraulic
supply system.
15. The modular actuator of claim 14, further comprising a
self-contained source of electrical power positioned within said at
least housing, wherein said self-contained source of electrical
power is the primary source of electrical power for said modular
actuator.
16. The modular actuator of claim 14, wherein said self-contained
source of electrical power comprises at least one battery.
17. The modular actuator of claim 14, wherein said self-contained
hydraulic supply system comprises a pressure intensifier.
18. The modular actuator of claim 14, wherein said self-contained
hydraulic system positioned within said housing comprises a pump
driven by an electrical motor.
19. The modular actuator of claim 14, wherein said self-contained
hydraulic system comprises at least one fluid reservoir and a
control/vent valve.
20. The modular actuator of claim 14, wherein said modular actuator
further comprises means for releasably coupling said modular
actuator to said subsea device.
21. The modular actuator of claim 14, wherein said self-contained
hydraulic supply system is adapted to supply a pressurized fluid
employed in actuating a subsea valve.
22. The modular actuator of claim 14, wherein said modular actuator
is adapted to be releasably coupled to said subsea device by an
ROV.
23. A modular actuator adapted to be releasably coupled to a subsea
device, comprising: a hydraulic actuator; at least one housing; and
a self-contained hydraulic supply system positioned within said at
least one housing, said self-contained hydraulic supply system
comprising: a pump driven by an electrical motor; at least one
fluid reservoir; and a control/vent valve.
24. The modular actuator of claim 23, further comprising a control
system positioned within said at least one housing to control
delivery of a high pressure hydraulic fluid produced by said
self-contained hydraulic supply system.
25. The modular actuator of claim 23, further comprising a
self-contained source of electrical power positioned within said at
least one housing, wherein said self-contained source of electrical
power is the primary source of electrical power for said modular
actuator.
26. The modular actuator of claim 25, wherein said self-contained
source of electrical power comprises at least one battery.
27. The modular actuator of claim 23, wherein said modular actuator
further comprises means for releasably coupling said modular
actuator to said subsea device.
28. The modular actuator of claim 23, wherein said self-contained
hydraulic supply system is adapted to supply a pressurized fluid
employed in actuating a subsea valve.
29. A modular actuator adapted to be releasably coupled to a subsea
device, comprising: a hydraulic actuator; at least one housing; a
self-contained hydraulic supply system positioned within said at
least one housing, said self-contained hydraulic supply system
comprising: a pump driven by an electrical motor; at least one
fluid reservoir; and a control/vent valve; a control system
positioned within said at least one housing to control delivery of
a high pressure hydraulic fluid produced by said self-contained
hydraulic supply system; and a self-contained source of electrical
power positioned within said at least one housing, wherein said
self-contained source of electrical power is the primary source of
electrical power for said modular actuator.
30. The modular actuator of claim 29, wherein said self-contained
source of electrical power comprises at least one battery.
31. The modular actuator of claim 29, wherein said modular actuator
further comprises means for releasably coupling said modular
actuator to said subsea device.
32. The modular actuator of claim 29, wherein said self-contained
hydraulic supply system is adapted to supply a pressurized fluid
employed in actuating a subsea valve.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention is generally directed to the field of
actuators, and more particularly to a modular actuator for subsea
valves and equipment, and various methods of using same. In one
illustrative example, the present invention is directed to a system
for controlling an actuator for a downhole safety valve in a subsea
Christmas tree.
[0003] 2. Description of the Related Art
[0004] The production from a subsea well is controlled by a number
of valves that are assembled into a Christmas tree. The actuation
of the valves is normally dependent upon hydraulic fluid to operate
hydraulic actuators for the valves and is therefore entirely
dependent upon an external source for the supply of pressurized
hydraulic fluid. Hydraulic power is normally supplied through an
umbilical running from a station located on a vessel on the surface
or, less common, from a land based station. Usually the actuators
are controlled by pilot valves housed in a control module located
at or near the subsea installation, the pilot valves directing the
supply of hydraulic fluid to each actuator, as dictated by the need
for operation. The pilot valves may be operated by electric means
and such a system is therefore called an electro-hydraulic
system.
[0005] The design of actuators and valves for subsea wells are
dictated by stringent demands on the standard and function for
these valves, because of the dangers of uncontrolled release of
hydrocarbons. A typical demand is that these valves must be
failsafe closed, meaning that they must close upon loss of power or
control. The only practical means today in subsea environments is
to use springs that are held in the compressed state by the
hydraulic pressure, keeping the valve open, and will be released in
the event of loss of hydraulic pressure, thus closing the valve.
The spring force needed to close a valve is dependent upon both
well pressure and ambient pressure, with larger ambient pressure
demanding larger springs.
[0006] For the control of subsea wells, a connection between the
well and a monitoring and control station must be established. This
station can either be located in a floating vessel near the subsea
installations or in a land station a long distance away.
Communication between the control station and the subsea
installation is normally provided by installing an umbilical
between the two points. The umbilical contains lines for the supply
of hydraulic fluid to the various actuators in or by the well,
electric lines for the supply of electric power and signals to
various monitoring and control devices and lines for signals to
pass to and from the well. This umbilical is a very complicated and
expensive item, costing several thousand dollars per meter.
[0007] It would therefore be very cost-saving to be able to
eliminate the umbilical. Proposals have been made to use
electrically operated actuators for subsea valves instead of the
traditional hydraulic actuators, see for example U.S. Pat. Nos.
5,497,672 and 5,984,260. However, this entails the installation of
completely new actuators, resulting that it is not possible to
retrofit a hydraulic system with an electric actuator.
[0008] EP Patent Application No. 1209294 discloses an
electro-hydraulic control unit with a piston/cylinder arrangement
with the piston dividing the cylinder into two chambers, a fluid
connection between the two chambers and a valve to configure the
fluid flow such that pressureized hydraulic fluid only may flow in
one direction, but not in both directions.
[0009] U.S. Pat. No. 6,269,874 discloses an electro-hydraulic
surface controlled subsurface safety valve actuator that comprises
an electrically actuated pressure pump and a dump valve that is
normally open so that if power fails, the pressure is released and
the safety valve closes.
[0010] The present invention is directed to an apparatus for
solving, or at least reducing the effects of, some or all of the
aforementioned problems.
SUMMARY OF THE INVENTION
[0011] The present invention is directed to a modular actuator for
subsea valves and equipment, and various methods of using same. In
one illustrative embodiment, the actuator comprises a hydraulic
actuator, at least one housing and a self-contained hydraulic
supply system positioned within the at least one housing.
[0012] In another illustrative embodiment, the actuator comprises a
hydraulic actuator, at least one housing and a plurality of
components positioned within the at least one housing, the
components comprising a self-contained hydraulic supply system and
a control system to control delivery of a high pressure hydraulic
fluid produced by the self-contained hydraulic supply system.
[0013] In yet another illustrative embodiment, the actuator
comprises a hydraulic actuator, at least one housing and a
self-contained hydraulic supply system positioned within the at
least one housing, the self-contained hydraulic supply system
comprising a pump driven by an electrical motor, at least one fluid
reservoir and a control/vent valve.
[0014] In a further illustrative embodiment, the actuator comprises
a hydraulic actuator, at least one housing and a self-contained
hydraulic supply system positioned within the at least one housing,
the self-contained hydraulic supply system comprising a pump driven
by an electrical motor, at least one fluid reservoir and a
control/vent valve. The actuator further comprises a control system
positioned within the at least one housing to control delivery of a
high pressure hydraulic fluid produced by the self-contained
hydraulic supply system and a self-contained source of electrical
power positioned within the at least one housing, wherein the
self-contained source of electrical power is the primary source of
electrical power for the modular actuator.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The invention may be understood by reference to the
following description taken in conjunction with the accompanying
drawings, in which like reference numerals identify like elements,
and in which:
[0016] FIG. 1 is a schematic depiction of one illustrative
embodiment of the present invention employed in connection with a
subsea valve;
[0017] FIG. 2 is another schematic depiction of an alternative
embodiment of the present invention employed in connection with a
subsea equipment item;
[0018] FIGS. 3a-3f describe various aspects of a modular actuator
in accordance with one illustrative embodiment of the present
invention;
[0019] FIG. 4 is a schematic depiction of an illustrative modular
actuator in accordance with one embodiment of the present
invention;
[0020] FIG. 5 is a depiction of yet another illustrative embodiment
of a modular actuator in accordance with the present invention;
[0021] FIG. 6 is a more detailed schematic depiction of one
illustrative embodiment of the present invention in a first working
mode;
[0022] FIG. 7 is a detailed schematic depiction showing one
illustrative embodiment of the present invention in a fail safe
mode;
[0023] FIG. 8 is yet another illustrative embodiment of the present
invention employing an alternative valve arrangement; and
[0024] FIGS. 9a-9c depict an illustrative embodiment of the present
invention in various operating configurations.
[0025] While the invention is susceptible to various modifications
and alternative forms, specific embodiments thereof have been shown
by way of example in the drawings and are herein described in
detail. It should be understood, however, that the description
herein of specific embodiments is not intended to limit the
invention to the particular forms disclosed, but on the contrary,
the intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the invention
as defined by the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
[0026] Illustrative embodiments of the invention are described
below. In the interest of clarity, not all features of an actual
implementation are described in this specification. It will of
course be appreciated that in the development of any such actual
embodiment, numerous implementation-specific decisions must be made
to achieve the developers' specific goals, such as compliance with
system-related and business-related constraints, which will vary
from one implementation to another. Moreover, it will be
appreciated that such a development effort might be complex and
time-consuming, but would nevertheless be a routine undertaking for
those of ordinary skill in the art having the benefit of this
disclosure.
[0027] The present invention will now be described with reference
to the attached figures. The words and phrases used herein should
be understood and interpreted to have a meaning consistent with the
understanding of those words and phrases by those skilled in the
relevant art. No special definition of a term or phrase, i.e., a
definition that is different from the ordinary and customary
meaning as understood by those skilled in the art, is intended to
be implied by consistent usage of the term or phrase herein. To the
extent that a term or phrase is intended to have a special meaning,
i.e., a meaning other than that understood by skilled artisans,
such a special definition will be expressly set forth in the
specification in a definitional manner that directly and
unequivocally provides the special definition for the term or
phrase.
[0028] In the following description, the term fluid line is used to
indicate a fluid connection between components of the system. It
should be understood that in various embodiments, the fluid
connection between components may comprise an actual fluid conduit
such as a pipe or hose, or the components may be connected directly
to each other. Any configuration which allows for fluid
communication between components as described below is considered
to be within the spirit and scope of the invention.
[0029] In the specification, terms such as "upward" or "downward"
or the like may be used to refer to the direction of fluid flow
between various components of the devices depicted in the attached
drawings. However, as will be recognized by those skilled in the
art after a complete reading of the present application, the device
and systems described herein may be positioned in any desired
orientation. Thus, the reference to the direction of fluid flow
should be understood to represent a relative direction of flow and
not an absolute direction of flow. Similarly, the use of terms such
as "above," "below," or other like terms to describe a spatial
relationship between various components should be understood to
describe a relative relationship between the components as the
device described herein may be oriented in any desired
position.
[0030] Also in the following description, the terms low pressure
and high pressure are used to describe various portions of the
system. It should be understood that these terms are used in a
relative sense. Low pressure is used to describe the fluid supply
and the portions of the system in fluid communication with the
fluid supply. High pressure is used to describe the fluid which is
pressurized by the pump or other pressure intensifying device, and
the portions of the system in fluid communication with pump output.
The term high pressure is used only to indicate that this portion
of the system is at a higher pressure relative to the fluid supply.
The term low pressure is used only to indicate that this portion of
the system is at a lower pressure than the pump output. The actual
absolute or gauge pressure of the various portions of the system is
irrelevant to the definition of high or low pressure.
[0031] FIGS. 1 and 2 schematically depict illustrative systems 10
employing a modular actuator 16 in accordance with various aspects
of the present invention. As depicted in FIG. 1, the modular
actuator 16 is operatively coupled to a valve actuator 15 that is
operatively coupled to a subsea valve 12 positioned in a flow line
or well conduit 14. The valve actuator 15 may be of any type, e.g.,
a mechanical valve actuator, a hydraulic valve actuator, etc. Thus,
the particular type of valve actuator disclosed herein should not
be considered a limitation of the present invention. In the
embodiment depicted in FIG. 2, a plurality of modular actuators 16
are operatively coupled to valve actuators 15 that, in turn, are
operatively coupled to a item of subsea equipment 18, such as an
illustrative Christmas tree. As will be described more fully below,
in one illustrative embodiment, the modular actuator 16 of the
present invention is a self-contained actuator that is adapted to
actuate a subsea valve 12 or other similar type component. In the
illustrative embodiment depicted in FIG. 2, the plurality of
modular actuators 16 are adapted to control a plurality of valves
(not shown) positioned internally within the schematically depicted
Christmas tree 18.
[0032] As will be described more fully below, the modular actuator
16 described herein comprises a self-contained power supply, and it
may be readily decoupled from the valve actuator 15 and removed to
the surface. Importantly, in one illustrative embodiment, the
modular actuator 16 described herein comprises a self-contained
hydraulic system that will be used, at least in part, to actuate
the subsea valve 12 or other like equipment. In accordance with one
illustrative aspect of the present invention, since the modular
actuators 16 described herein employ a self-contained hydraulic
system, a supply of high pressure hydraulic fluid from a station
location on a surface vessel or from a land-based station is not
required. Moreover, the modular actuator 16 disclosed herein is
configured so that it may be easily coupled and decoupled from the
subsea equipment, e.g., the valve actuator 15, to which it is
attached by a variety of techniques, e.g., by use of an ROV
(remotely operated vehicle), a diver, etc., and retrieved to the
surface as necessary for repairs.
[0033] FIGS. 3a-3f depict one illustrative embodiment of the
modular actuator 16 in accordance with the present invention. In
general, the modular actuator 16 comprises a hydraulic actuator and
one or more housing portions that are adapted to contain various
components of the modular actuator 16, including a self-contained
hydraulic supply system. As depicted in FIGS. 3a-3f, the modular
actuator 16 comprises a linear override tool 16A and housings 16B,
16C, 16D for housing various electrical and hydraulic components,
including hydraulic fluid, associated with the modular actuator 16.
Although the illustrative embodiment depicted herein comprises
three separate housings 16B, 16C, 16D, those skilled in the art,
with the benefit of the present disclosure, will understand that
the modular actuator 16 may comprise one or more housings to house
the various components of the system described herein. Thus, the
present invention should not be considered as limited to the
illustrative embodiments depicted herein.
[0034] In the depicted embodiment, an interface device 17 may be
provided between the modular actuator 16 and the valve actuator 15.
Even more specifically, in the illustrative example depicted
herein, the interface device 17 may comprise a spool having a first
flange 17A, a second flange 17B and a travel indicator 17C. The
first flange 17A is adapted to be coupled to the valve actuator 15.
Typically, the interface device 17 may be coupled to the valve
actuator 15 at the time the subsea system is placed into service.
Thereafter, the modular actuator 16 may be operatively coupled to
the flange 17B when desired or needed, as will be described more
fully below. As will be recognized by those skilled in the art
after a complete reading of the present application, the interface
device 17 may take a variety of shapes and forms. For example, in
one illustrative embodiment, the interface device 17 may be
designed in accordance with the teachings of a standard entitled
"Design and Operation of Subsea Production Equipment Systems,"
ISO/FDIS 13628-8:2000(E), pp. 39-42. In other embodiments, a
separate interface device 17 need not be provided. That is, to the
extent an interface is provided, it may be provided as an integral
part of either the valve actuator 15 or the modular actuator
16.
[0035] As to more specifics, the modular actuator 16 may comprise a
hydraulic fluid reservoir 16D, an ROV handle 16E, an ROV handle
16F, a shaft 16G and a plurality of seals 16H. The modular actuator
16 is provided with a recess 161 that is adapted to be positioned
around the flange 17B of the interface device 17. A plurality of
anti-rotation devices 16J, e.g., studs or nuts, are provided to
reduce or prevent rotation of the modular actuator 16 relative to
the interface device 17.
[0036] FIGS. 3a-3c depict the modular actuator 16 as it is being
lowered onto the flange 17B of the interface device 17. An ROV may
be used to install the modular actuator 16. As indicated
previously, in one illustrative embodiment, the interface device 17
is attached to the valve actuator 15 as part of the initial
installation process of the subsea system. Any number of valves of
a particular subsea system may be provided with such an interface
device 17 such that a modular actuator 16 may be operatively
coupled to such valves when needed. More specifically, in one
illustrative embodiment, an ROV (remotely operated vehicle) or
other like device may be employed to position the modular actuator
16 in a position where it may operate a subsea devices, such as a
valve. The modular actuator 16 may be lowered onto the flange 17B
through use of an ROV that grasps ROV handle 16E. FIG. 3c depicts
the modular actuator 16 in the fully landed position. The recess
16I is sized such that the modular actuator 16 fits securely around
the flange 17B. The anti-rotation devices 16J prevent or reduce
rotation of the modular actuator 16 relative to the interface
device 17 and the valve actuator 15. When the modular actuator 16
is in a horizontal position, the weight of the modular actuator 16,
along with the closeness of fit between the recess 16I and the
flange 17B, tend to secure the modular actuator 16 in position.
With reference to FIG. 3E, when the modular actuator 16 is
activated or stroked, the shaft 16G will extend into the bore of
the interface device 17 thereby insuring that the modular actuator
16 remains in place irrespective of whether the valve actuator 15
is positioned horizontally, vertically, or at any other angle.
Additional operational aspects of the modular actuator 16 will be
described more fully below.
[0037] Illustrative examples of the associated electrical and
hydraulic controls that may be employed with the modular actuator
16 are depicted in FIG. 3f. As shown therein, the system comprises
an accumulator 16K, a pump 16L, driven by an electric motor 16M, a
check valve 16N, pressure sensors 16O, 16P, 16Q, a filter 16R and a
solenoid valve with spring return 16S. In one illustrative
embodiment, the solenoid valve 16S may be a normally closed valve,
as depicted in FIG. 3f. When the solenoid valve 16S is actuated and
moved to its "open" position, the pump 16L may be activated to
increase the pressure of the hydraulic fluid supplied to the
chamber 16T. In turn, this causes the shaft 16G to move to the
right in FIG. 3f, as indicated by the arrow 16U. The end 16W of the
shaft 16G engages the end 15B of the shaft 15A (see FIG. 3e) of the
valve actuator 15 when the shaft 16G moves in the direction of the
arrow 16U. The pump 16L continues to operate until the pressure on
both sides of the solenoid valve 16S is substantially equal, as
determined by the pressure sensors 16P, 16Q. At that point, the
shaft 16G is fully extended and the pump 16L may be stopped.
[0038] When the solenoid valve 16S is de-energized, e.g., in an
emergency situation, the solenoid valve 16S returns (due to its
spring return) to its closed position, as depicted in FIG. 3f. With
the solenoid valve 16S in the closed position, the high pressure
hydraulic fluid in the chamber 16T is free to return to the
accumulator 16K, and the shaft 16G is free to travel to the left in
FIG. 3f, as indicated by the arrow 16V, until it reaches its fully
retracted position. A force, such as a spring force, may be
supplied to urge the shaft 16G to its fully retracted position.
Such a force may be supplied by, for example, a return spring on a
subsea safety valve. A portion of the shaft 16G will remain
positioned within the bore of the interface device 17 even when the
solenoid valve 16S is in its closed position (as shown in FIG. 3f).
In one embodiment, to fully retract the shaft 16G from inside the
bore of the interface device 17, an ROV is employed to grasp and
pull on the handle 16F (see FIG. 3e). Once the shaft 16G has been
complete disengaged from the bore of the interface device 17, the
modular actuator 16 may be removed by use of an ROV that grasps the
handle 16E. An ROV may be used to open or close a needle valve 16Y
(see FIG. 3F), via handle 16X (see FIG. 3e), to vent the system if
the need arises. A travel indicator 17C may be used to determine
the movement of the shaft 15A. The travel indicator 17C is secured
to the shaft 15A by a bolt 17D (see FIG. 3e). The bolt 17D is free
to travel within the groove 17E.
[0039] FIG. 4 is a schematic depiction of the various components
that may be included in one illustrative embodiment of the modular
actuator 16 disclosed herein. As shown in FIG. 4, a variety of
components are positioned in a one or more housings, generally
indicated by the number 20, associated with the modular actuator
16. The exact number of housings and the location of various
components of the system described herein may vary depending upon
the particular application. Of course, the modular actuator 16 will
ultimately be operatively coupled to an illustrative valve actuator
15. In general, the modular actuator 16 comprises, in one
illustrative embodiment, a fluid reservoir-accumulator 44, a
pressure intensifier 47, a check valve 34, a control/vent solenoid
valve 40, a battery 54 and a control system 50. A plurality of
hydraulic flow lines 45, 36, 48 and 42 are positioned within the
housing 20. The modular actuator 16 further comprises an
illustrative electrical connection 36 that is adapted to mate with
a schematically depicted electrical line 37.
[0040] The pressure intensifier 47 schematically depicted in FIG. 4
may be comprised of a variety of devices. The pressure intensifier
47 may be any device or system that employs electrical power to
increase the pressure in a fluid. For example, in one embodiment,
the pressure intensifier 47 may be a rotary pump driven by a
schematically depicted electric motor 31 shown in FIG. 4. In
another illustrative embodiment, the pressure intensifier 47 may
also be a reciprocating pump driven by an electric motor (see,
e.g., FIGS. 9a-9c). In the illustrative embodiment depicted in FIG.
4, the system within the modular actuator 16 is adapted to provide
a high pressure hydraulic fluid to a component, such as the
illustrative subsea valve 12, to accomplish the desired purpose,
e.g., to move a valve from a first position to a second
position.
[0041] Electrical power for the electrical components within the
housing 20 may be provide by an electrical line that extends to a
surface source of electrical power or it may be provided by one or
more batteries that are positioned inside the housing 20 or
otherwise located proximate to the modular actuator 16. Moreover,
depending upon the particular application the batteries may be the
primary source of electrical power for the electrical components
within the housing 20. In one illustrative embodiment, the battery
54 (see FIG. 4) is positioned in the housing 20 and it is the
primary source of power for the electrical components of the
modular actuator 16, e.g., the motor 31, the control system 35, the
solenoid control/vent valve 40, etc. Thus, in this embodiment, the
modular actuator 16 also has a self-contained electrical power
source. The battery 54 (or groups thereof) may be any of a variety
of commercially available batteries employed in subsea
applications.
[0042] Recharging the battery 54 may be accomplished by a
substantially continuous trickle charge that is applied to the
battery 54. Alternatively, the control system 35 may be employed to
monitor the stored charge in the battery 54 and when it reaches a
certain minimum allowed level, the battery 54 may be recharged by
temporarily coupling it to a full power electrical line. In other
embodiments, electrical power to the electrical components with the
housing 20 may be provide by a traditional electrical power line or
cable and the battery 54, if present, may serve a traditional
back-up role.
[0043] If it is desired to replace the battery 54 within the
housing 20 of the modular actuator 16, then the modular actuator
may be decoupled from the subsea valve 12 or equipment 18 and taken
to the surface. As described previously, an ROV or diver may be
employed to decouple the modular actuator 16 from the subsea valve
12 or equipment 18 and transport it to the surface.
[0044] The illustrative control system 50 depicted within the
modular actuator 16 is adapted to sense various conditions existing
within the system contained in the modular actuator 16 and take
various control actions in response thereto, as described more
fully below. The control system 35 may take a variety of shapes and
forms. In one illustrative embodiment, the control system 50
comprises a programmable logic device or a microprocessor and a
memory device for storing a variety of data and/or programs.
[0045] FIG. 5 depicts yet another illustrative embodiment of the
modular actuator 16 described herein. Relative to the embodiment
depicted in FIG. 4, in the embodiment depicted in FIG. 5, a
hydraulic actuator 28 (having a shaft or stem 21 and an end
interface 27) has been included in the modular actuator 16. In this
illustrative embodiment the interface 27 of the hydraulic cylinder
28 may be coupled to any of a variety of devices, e.g., a subsea
valve, and actuated to open or close such a valve.
[0046] FIG. 6 is a more detailed depiction of some of the various
components of the modular actuator 16 in accordance with one
illustrative embodiment of the present invention. For ease of
reference many of the components shown in FIGS. 1-5 will be shown
in FIGS. 6-8 with a corresponding "1" prefix. As shown therein, an
actuator 128 has a cylindrical housing 112. A piston 114 is axially
movable in the housing, between first and second positions. A stem
121 is attached to the piston 114 and extends outside the housing
112. An illustrative flange or bracket 122 is provided for
operatively coupling the actuator 129 to a subsea valve (not shown
in FIG. 6). In one illustrative embodiment, the actuator 129 is
provided with a handle 124 that enables the actuator 129 to be
transported and mounted with an ROV. A linear override tool 120 may
also be used for manually moving the piston 114, using an ROV tool.
The actuator 129 depicted in FIG. 6 may be employed with a modular
actuator 16 like the one schematically depicted in FIG. 4. Of
course, the actuator 129 depicted in FIG. 6 may also be employed
with a modular actuator 16 like the one schematically depicted in
FIG. 5, wherein the actuator 129 is positioned within the housing
20 of the modular actuator 16. Of course, in that case, the
actuator 129 may not be provided with a separate ROV handle 124 or
the linear override tool 120.
[0047] The piston 114 includes seals 111 to seal the piston 114
against the cylinder. The piston 114 defines first 113 and second
115 (see FIG. 7) chambers in the housing 112. A fluid line 142
connects the second chamber 115 with a variable volume fluid
reservoir-accumulator 144. In one illustrative embodiment, the
fluid in accumulator 144 is at ambient sea pressure. The variable
volume accumulator 144 evens out pressure surges in the return
system and also provides for spare fluid capacity, as is well known
in the art. A fluid line 145 connects the accumulator 144 with the
intake side of an illustrative pressure intensifier, e.g., a pump
147. A stub fluid line with a coupling 143 can be incorporated into
the fluid line 145, to enable fluid to be replenished and refill
the accumulator 144. A fluid line 136 connects the first chamber
113 with the pressure side of pump 147. A one-way valve or check
valve 134 is installed in fluid line 136, allowing fluid to flow
only towards chamber 113.
[0048] An additional fluid line 148 interconnects fluid lines 145
and 136. In fluid line 148 there is mounted a control-vent solenoid
valve 140, the valve 140 being movable between a closed position
(FIG. 7) preventing fluid flow through line 148, and an open
position (FIG. 8) allowing fluid flow through line 148. As seen
from FIG. 8, when valve 140 is in its open position fluid may flow
in either direction between the first chamber 113 and the second
chamber 115. A spring 139 is arranged to bias the valve 140 towards
its open position. A solenoid 138 may be selectively energized to
move the valve 140 to its closed position, against the biasing
force of the spring 139.
[0049] The pump 147 is operated by a motor 131. Pressure and
temperature sensors 127 and 133 are mounted in fluid lines 136 and
145, respectively. A filter unit 146 may be installed in fluid line
145 between the pump intake and the fluid supply 144.
[0050] The various parts of the unit are in communication with a
control module 150 through cables 126, 128, 130 and 132. The
control module 150 is in communication with a remote station (not
shown) via a cable 152, to receive power and communication signals
therefrom.
[0051] In one illustrative embodiment, the motor 131 is a brushless
DC motor. Also, in one illustrative embodiment, the control module
150 includes a battery 154 to provide primary power to the motor
131 and the solenoid 138. The battery 154 may be trickle-charged
from a local power source or from a remote location. In this
instance, only a small cable would be needed to charge the battery
154. Alternatively, primary electrical power may be supplied from a
remote location and the battery 154, if present, may merely serve
as a traditional back-up source for an emergency supply of
electrical power.
[0052] FIG. 7 depicts the present invention in a fail safe mode. As
shown therein, a subsea valve 212 is adapted to be operated by the
actuator 129. The valve 212 comprises a valve element 202 connected
to a valve stem 204, the valve stem 204 extending into and through
a spring housing 206. A spring 208 is located in the spring housing
206. The valve stem 204 has a spring actuating flange 210 rigidly
attached thereto. The valve stem 204 terminates in a standard
interface mechanism 211. The piston stem 121 has at its end a
corresponding interface 127, allowing the valve stem 204 to be
operably connected to the piston stem 121.
[0053] In FIG. 7, the valve element 202 is depicted in the closed
position. To move the valve element 202 to its open position, the
solenoid 138 is energized to move the two-way valve 140 to the
closed position shown in FIG. 7, against the force of the spring
129. This closes the fluid path between chambers 113 and 115 of the
actuator 128. Then the motor 131 is operated to drive the pump 147,
thus transferring fluid from the low pressure portion of the system
(comprising the second chamber 115 and the accumulator 144) to the
first chamber 113 of the actuator 129. The high pressure fluid in
chamber 113 displaces the piston 114 to its second (extended)
position, shown in FIG. 8.
[0054] Consequently, this will move the valve stem 204, causing the
valve element 202 to move to its open position (not shown in FIG.
7). Pressure sensor 127 senses the pressure in fluid line 136, and
the control module 150 cuts power to the motor 131 when the
pressure in line 136 is sufficient to drive the valve stem 206
against the power of the spring 208. One-way valve 134 and
two-way-valve 140 prevent high pressure fluid from exiting chamber
113, thus ensuring that the valve element 202 is held in its open
position. In moving the valve element 202 to its open position, the
spring 208 is compressed thereby creating a bias return force in
the spring 208 that will tend to move the valve element 202 to its
closed position.
[0055] When it becomes necessary to close the valve 202, either
electively or in an emergency situation, power to the solenoid 138
is shut off, causing the two-way valve 140 to move to its open
position shown in FIG. 8 as a result of the biasing force provided
by the spring 139. This opens the fluid communication path between
first 113 and second 115 chambers, and blocks or shuts off flow
from the pump 147 to the first chamber 113. Since the pressure now
is equalized on each side of the piston 114, the spring 208 will
force the piston 114 and stem 116 backwards to its first
(retracted) position, and the valve 202 will close as fluid is
transferred to chamber 115 from chamber 113.
[0056] FIG. 8 shows a system similar in many respects to the system
of FIG. 6. However, in FIG. 8, a flow line 167 extends between
chamber 113 of the actuator 129, and a first port of a three-way
solenoid valve 160. A second port of valve 160 is connected to flow
line 136, which is in turn connected to the output of pump 147. A
third port of valve 160 is connected to flow line 168, which is in
turn connected to flow line 145. The valve 160 is biased towards a
first, or venting position (not shown) by a spring 161. A solenoid
162 is selectively operable to move valve 160 to a second position,
as shown in FIG. 8. In the second position, the valve 160 allows
fluid communication between the output of pump 147 and the first
chamber 113. In this position, flow line 168 is blocked. High
pressure fluid from the pump 147 is introduced into the chamber 113
of the actuator 128, thus driving the stem 121 to its extended
position which opens the valve element 202.
[0057] When it becomes necessary to close the valve 202, either
electively or in an emergency situation, power to the solenoid 162
is shut off, causing the three-way valve 160 to move to its first,
or venting position. This opens the fluid communication path
between first 113 and second 115 chambers, and blocks flow from the
pump to the first chamber 113. Since the pressure now is equalized
on each side of the piston 114, the spring 208 will force the
piston 114 and stem 121 backwards to its first (retracted)
position, and the valve 202 will close as fluid is transferred to
chamber 115 from chamber 113.
[0058] The solenoid valve 160 is pressure-balanced, as will be
clearly understood from FIG. 8. The required biasing force of the
spring 161 is very small, and thus the required holding force of
the solenoid 162 may be correspondingly small.
[0059] The modular actuator 16 according to the present invention
may be made very small and compact. It is releasably connected to
the valve 212 making it easy to replace or retrieve for repairs or
maintenance. The hydraulic portion of the system is entirely
self-contained within the housing 20 of the modular actuator 16.
Thus, no external hydraulic lines are necessary--control signals
and power are transmitted through a simple and inexpensive
electrical cable arrangement. The modular nature of the actuator 16
also makes it possible to exchange the actuator 16 with other types
of actuators, such as an all-electric actuator. It is also possible
to retrofit the actuator 16 onto a valve which was previously
manually operated. Once the valve 212 has been fully actuated, the
actuator 16 of the present invention requires very little power to
hold the valve in position.
[0060] Another exemplary embodiment of a modular actuator 16 in
accordance with the present invention is shown schematically in
FIGS. 9a-9c. A hydraulic power unit (HPU) 380 is positioned within
the housing 20 of the modular actuator 16. For convenience, the
illustrative control system 50 and battery 54 are not depicted in
FIGS. 9a-9c. The unit 380 includes a master cylinder 381 with a
piston 382 reciprocally movable axially in the cylinder, thus
dividing the cylinder into two chambers 383 and 384. The two
chambers 383 and 384 are interconnected through a bypass line 391,
the flow through the bypass being controlled by a bypass control
valve 390.
[0061] In the exemplary embodiment the actuator that moves piston
382 may consist of an electric motor with a gearbox and
transmission. In the exemplary embodiment, an electric motor 385 is
operatively connected to a shaft 386 by a suitable gearbox 375,
such that operation of motor 385 may precisely control the motion
of piston 382. Examples of a suitable motor 385 and gearbox 375
combination include a Model Number TPM 050 sold by the German
company Wittenstein. The motor may alternatively be a linear
electric motor.
[0062] In the well tubing there is mounted a controllable downhole
safety valve 346, known in the art as an SCSSV (Surface Controlled
Subsurface Safety Valve). As is well known in the art, the SCSSV
includes a hydraulic cylinder including a "slave" chamber 393. To
actuate the SCSSV, chamber 393 is pressurized, pushing a piston 394
against the biasing force of a spring 395 to open the valve 346. A
fluid line 387 is connected between the slave chamber 393 with an
outlet port 398 of an operation control valve 388 positioned within
the housing 20. A first inlet port 396 of operation control valve
388 is connected to fluid line 389, which is connected to cylinder
chamber 383. This arrangement controls the flow of fluid from
master cylinder 381 to the SCSSV actuator 374. A check valve 399 is
mounted in line 389, between the operation control valve 388 and
the chamber 383. The check valve 399 allows fluid to flow from
chamber 383 to chamber 393, but not the reverse.
[0063] An accumulator 400, containing a supply of hydraulic fluid,
is connected to the fluid line 387 via line 401, at a point between
operation control valve 388 and check valve 399. The accumulator
400 provides a buffer for the high pressure hydraulic fluid, and
ensures that the SCSSV will stay open under normal operating
conditions.
[0064] A pressure balanced compensator 405 is connected to a second
inlet port 397 of operation control valve 388 via line 406. A fluid
line 408 connects compensator 405 with chamber 384 of master
cylinder 381. A fluid line 409 connects compensator 405 with a
hydraulic coupling 411. The coupling 411 allows hydraulic fluid to
be supplied from an external source (not shown) so that fluid can
be added to the hydraulic system.
[0065] Referring to FIG. 9a, when the motor 385 is energized, the
piston 382 will move downward in the master cylinder 381. This
forces high-pressure fluid through the line 387 to the slave
cylinder 393 in the downhole valve actuator 374, with the operation
control valve 388 in a first or open position. On the downstroke,
the chamber 384 of master cylinder 381 is refilled from compensator
405. Check valve 399 and accumulator 400 cooperate to maintain the
pressure in the line 387 at a level that will hold the SCSSV valve
open. Referring to FIG. 9b, to close the SCSSV valve, the operation
control valve 388 is shifted to its second or closed position. In
the second position, operation control valve 388 allows fluid to
flow back up through line 387, through line 406 and back into
compensator 405. In other words, the slave chamber 393 of the
downhole actuator is vented through operation control valve 388 to
the low-pressure system.
[0066] The pressure differential across piston 382 will normally
force the piston back to its upper starting position when the motor
is de-energized. However, under certain conditions it may be
necessary to reset the piston 382 to the upper position. To do
this, bypass control valve 390 is shifted to a second, or open
position, as shown in FIG. 9c. In the second position, bypass
control valve 390 allows fluid to flow through the bypass line
between the two chambers 383 and 384 of the master cylinder. The
electric motor 385 may then be run in reverse in order to move the
piston 12 back to the upper starting position.
[0067] Referring to FIG. 9b, when it is desired to recharge the
accumulator 400, the operation control valve 388 may or may not be
shifted to its second position and the motor 385 is energized to
drive the piston 382 downward in master cylinder 381. A pressure
sensor 413 in line 401 monitors the pressure in the accumulator
400, making it possible to stop the motor 385 when desired pressure
is reached.
[0068] From time to time it may become necessary to replenish the
hydraulic fluid in the system, to replace fluid lost due to leaks,
for example. To accomplish this, an external source (not shown) of
hydraulic fluid may be coupled to the hydraulic coupler 411. Fluid
from the external source fills the compensator 405 and first
chamber 384 of master cylinder 381. By shifting the bypass control
valve 390 to its open position (FIG. 9c), fluid may also flow into
second chamber 383. Bypass control valve 390 may then be moved to
the closed position (FIG. 9b), and piston 382 may be moved
downwards to recharge the accumulator 400, as previously
described.
[0069] The exemplary embodiment of the invention shown in FIGS.
9a-9c includes a high-pressure section, including accumulator 400,
which is maintained at a pressure which is sufficient to operate
the SCSSV. This embodiment also includes a low-pressure section,
including compensator 405, which is maintained at a second pressure
which is less than the pressure required to operate the SCSSV. The
compensator 405 may be partly filled with an inert gas such as
nitrogen, which compensates for pressure differences due to
operation of the SCSSV, and which also primes the system for use at
various water depths.
[0070] By utilizing the exemplary embodiment of the modular
actuator 16 shown in FIGS. 9a-9c, a standard, hydraulically
actuated downhole safety-valve can be used while eliminating the
need for a high-pressure hydraulic fluid supply from the surface.
Standard downhole safety valves have a spring failsafe feature so
that the valve will close when pressure is relieved in the system.
The valve will therefore also close in the event of a hydraulic
system failure. In an emergency the SCSSV can quickly be closed by
shifting operation control valve 388 to its second position, thus
venting the high-pressure fluid from line 387.
[0071] The present invention is directed to a modular actuator for
subsea valves and equipment, and various methods of using same. In
one illustrative embodiment, the actuator comprises a hydraulic
actuator, at least one housing and a self-contained hydraulic
supply system positioned within the at least one housing.
[0072] In another illustrative embodiment, the actuator comprises a
hydraulic actuator, at least one housing and a plurality of
components positioned within the at least one housing, the
components comprising a self-contained hydraulic supply system and
a control system to control delivery of a high pressure hydraulic
fluid produced by the self-contained hydraulic supply system.
[0073] In yet another illustrative embodiment, the actuator
comprises a hydraulic actuator, at least one housing and a
self-contained hydraulic supply system positioned within the at
least one housing, the self-contained hydraulic supply system
comprising a pump driven by an electrical motor, at least one fluid
reservoir and a control/vent valve.
[0074] In a further illustrative embodiment, the actuator comprises
a hydraulic actuator, at least one housing and a self-contained
hydraulic supply system positioned within the at least one housing,
the self-contained hydraulic supply system comprising a pump driven
by an electrical motor, at least one fluid reservoir and a
control/vent valve. The actuator further comprises a control system
positioned within the at least one housing to control delivery of a
high pressure hydraulic fluid produced by the self-contained
hydraulic supply system and a self-contained source of electrical
power positioned within the at least one housing, wherein the
self-contained source of electrical power is the primary source of
electrical power for the modular actuator.
[0075] The particular embodiments disclosed above are illustrative
only, as the invention may be modified and practiced in different
but equivalent manners apparent to those skilled in the art having
the benefit of the teachings herein. For example, the process steps
set forth above may be performed in a different order. Furthermore,
no limitations are intended to the details of construction or
design herein shown, other than as described in the claims below.
It is therefore evident that the particular embodiments disclosed
above may be altered or modified and all such variations are
considered within the scope and spirit of the invention.
Accordingly, the protection sought herein is as set forth in the
claims below.
* * * * *