U.S. patent application number 12/530679 was filed with the patent office on 2010-04-22 for vortex induced vibration suppression systems and methods.
Invention is credited to Donald Wayne Allen, Stephen Paul Armstrong, Richard Bruce McDaniel, David Wayne McMillan, Janet Kay McMillan, Catherine Anne Preator, Christopher Steven West.
Application Number | 20100098497 12/530679 |
Document ID | / |
Family ID | 39759989 |
Filed Date | 2010-04-22 |
United States Patent
Application |
20100098497 |
Kind Code |
A1 |
Allen; Donald Wayne ; et
al. |
April 22, 2010 |
VORTEX INDUCED VIBRATION SUPPRESSION SYSTEMS AND METHODS
Abstract
A system comprising a subsea structure beneath a body of water,
subject to a water current; an installation vessel floating on the
body of water; a line connected to the subsea structure and the
installation vessel; and one or more vortex induced vibration
suppression devices connected to the line, which have been lowered
from the vessel to be installed on the subsea structure.
Inventors: |
Allen; Donald Wayne;
(Richmond, TX) ; Armstrong; Stephen Paul;
(Houston, TX) ; McDaniel; Richard Bruce; (Houston,
TX) ; Preator; Catherine Anne; (Houston, TX) ;
McMillan; David Wayne; (Deer Park, TX) ; McMillan;
Janet Kay; (Deer Park, TX) ; West; Christopher
Steven; (Pearland, TX) |
Correspondence
Address: |
SHELL OIL COMPANY
P O BOX 2463
HOUSTON
TX
772522463
US
|
Family ID: |
39759989 |
Appl. No.: |
12/530679 |
Filed: |
March 12, 2008 |
PCT Filed: |
March 12, 2008 |
PCT NO: |
PCT/US08/56655 |
371 Date: |
January 5, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60894748 |
Mar 14, 2007 |
|
|
|
Current U.S.
Class: |
405/211 |
Current CPC
Class: |
E21B 17/01 20130101;
B63B 2021/504 20130101; E21B 41/04 20130101; B63B 21/502
20130101 |
Class at
Publication: |
405/211 |
International
Class: |
E02D 31/00 20060101
E02D031/00 |
Claims
1. A system, comprising: a subsea structure beneath a body of
water, subject to a water current; an installation vessel floating
on the body of water; a line connected to the subsea structure and
the installation vessel; and one or more vortex induced vibration
suppression devices connected to the line, which have been lowered
from the vessel to be installed on the subsea structure.
2. The system of claim 1, wherein the subsea structure is selected
from an umbilical, a tubular, a riser, and a tendon.
3. The system of claim 1, wherein the vortex induced vibration
suppression device comprises a fairing or a helical strake.
4. The system of claim 1, wherein the line comprises at least two
lines, the votex induced vibration suppression devices connected to
the at least two lines.
5. The system of claim 1, wherein the vortex induced vibration
suppression devices are negatively buoyant in water.
6. The system of claim 1, wherein the vortex induced vibration
suppression devices comprise one or more shoulders adapted to
interface with a collar and/or other vortex induced vibration
suppression devices.
7. The system of claim 1, further comprising a spacer between two
adjacent vortex induced vibration suppression devices, the spacer
connected to the line.
8. The system of claim 1, further comprising a collar exterior to
the subsea structure, covering at least a portion of an outside
surface of the subsea structure.
9. The system of claim 8, wherein the line is connected to the
collar and the installation vessel.
10. A method, comprising: installing a subsea structure in a body
of water, wherein the subsea structure is subject to one or more
water currents; connecting at least one line to the subsea
structure and to a surface vessel; lowering at least one vortex
induced vibration suppression device from the vessel on the line;
and installing the vortex induced vibration suppression device from
the line to the exterior of the subsea structure, covering at least
a portion of an outside surface of the subsea structure.
11. The method of claim 10, further comprising: installing one or
more collars exterior to the subsea structure, the collars adapted
to retain the vortex induced vibration suppression devices in an
axial location along the subsea structure.
12. The method of claim 10, wherein a collar is installed on the
subsea structure before the subsea structure is installed in the
body of water.
13. The method of claim 10, wherein the vortex induced vibration
suppression device is installed on the subsea structure with a
remotely operated vehicle (ROV).
14. The method of claim 10, wherein the vortex induced vibration
suppression device comprises an automatic closing mechanism.
15. The method of claim 14, wherein the vortex induced vibration
suppression device is installed by moving the device adjacent to
the subsea structure to activate the automatic closing
mechanism.
16. The method of claim 10, wherein connecting at least one line to
the collar and to a surface vessel comprises connecting at least
two lines; and lowering at least one vortex induced vibration
suppression device from the vessel comprises lowering on the at
least two lines.
Description
RELATED APPLICATIONS
[0001] This application claims priority to co-pending U.S.
Provisional Application 60/894,748, filed Mar. 14, 2007, and having
attorney docket number TH3214. U.S. Provisional Application
60/894,748 is herein incorporated by reference in its entirety.
FIELD OF THE INVENTION
[0002] This invention is related to vortex induced vibration
suppression devices, and to systems and methods for attaching the
devices to structures to reduce drag and/or vortex induced
vibration (VIV).
BACKGROUND OF THE INVENTION
[0003] Whenever a bluff body in a fluid environment, such as a
cylinder, is subjected to a current in the fluid, it is possible
for the body to experience vortex-induced vibrations (VIV). These
vibrations may be caused by oscillating hydrodynamic forces on the
surface, which can cause substantial vibrations of the structure,
especially if the forcing frequency is at or near a structural
natural frequency.
[0004] Drilling for and/or producing hydrocarbons or the like from
subterranean deposits which exist under a body of water exposes
underwater drilling and production equipment to water currents and
the possibility of VIV. Equipment exposed to VIV may include
structures ranging from the tubes of a riser system, anchoring
tendons, hoses, umbilicals, and other subsea members.
[0005] There are generally two kinds of water current induced
stresses to which elements of a system may be exposed. The first
kind of stress as mentioned above is caused by vortex-induced
alternating forces that vibrate the underwater structure in a
direction perpendicular to the direction of the current. These are
referred to as vortex-induced vibrations (VIV). When water flows
past the structure, vortices are alternately shed from each side of
the structure. This produces a fluctuating force on the structure
transverse to the current. These vibrations can, depending on the
stiffness and the strength of the structure and any welds, lead to
unacceptably short fatigue lives. The second type of stress is
caused by drag forces which push the structure in the direction of
the current due to the structure's resistance to fluid flow. The
drag forces may be amplified by vortex induced vibrations of the
structure. For instance, a structure that is vibrating due to
vortex shedding will disrupt the flow of water around it more so
than a stationary umbilical. This results in greater energy
transfer from the current to the structure, and hence more
drag.
[0006] Many methods have been developed to reduce vibrations of sub
sea structures. Some of these methods to reduce vibrations caused
by vortex shedding from subsea structures operate by stabilization
of the wake. These methods include streamlined fairings, wake
splitters and flags. Streamlined or teardrop shaped, fairings that
swivel around a structure have been developed that almost eliminate
the shedding or vortexes. Other conventional methods to reduce
vibrations caused by vortex shedding from sub sea structures
operate by modifying the boundary layer of the flow around the
structure to prevent the correlation of vortex shedding along the
length of the structure. Examples of such methods include the use
of helical strakes around a structure, or axial rod shrouds and
perforated shrouds.
[0007] U.S. Pat. No. 6,695,539 discloses an apparatus and methods
for remotely installing vortex-induced vibration (VIV) reduction
and drag reduction devices on elongated structures in flowing fluid
environments. The apparatus is a tool for transporting and
installing the devices. The devices installed can include
clamshell-shaped strakes, shrouds, fairings, sleeves and flotation
modules. U.S. Pat. No. 6,695,539 is herein incorporated by
reference in its entirety.
[0008] Referring now to FIG. 1, surface structure 102 is in body of
water 100. Surface structure 102 is connected to subsurface
structure 103 at seabed 108 by connector member 104, such as a
tower, riser, cable, or tendon. Current 110 encounters connector
member 104. To protect connector member 104 from vibration caused
by current 110, fairings 114 have been installed. One or more
collars (not shown) may be installed between adjacent fairings.
[0009] When VIV suppression devices are installed on subsea
structures, each suppression device needs to be transported from a
surface vessel to the desired installation location on the
structure. One method to achieve this is to have a ROV travel to
the surface and install one device at a time. Other tools have been
proposed which can transport more than one device at a time on the
tool. Each trip to the surface to retrieve a device increases the
time and complexity of the installation.
[0010] There is a need in the art for improved systems and methods
for suppressing VIV. There is a need in the art for systems and
methods for suppressing VIV that do not suffer from the
disadvantages of the prior art.
[0011] There is a need in the art for systems and methods for
providing VIV suppression devices to structures, and for improved
installation systems and methods for the VIV suppression devices.
There is a need for systems and methods of installing VIV
suppression devices with fewer trips required to the surface.
[0012] These and other needs will become apparent to those of skill
in the art upon review of this specification, including its
drawings and claims.
SUMMARY OF THE INVENTION
[0013] In one aspect, the invention provides a system comprising a
subsea structure beneath a body of water, subject to a water
current; an installation vessel floating on the body of water; a
line connected to the subsea structure and the installation vessel;
and one or more vortex induced vibration suppression devices
connected to the line, which have been lowered from the vessel to
be installed on the subsea structure.
[0014] In another aspect, the invention provides a method,
comprising installing a subsea structure in a body of water,
wherein the subsea structure is subject to one or more water
currents; covering at least a portion of an outside surface of the
subsea structure; connecting at least one line to the subsea
structure and to a surface vessel; lowering at least one vortex
induced vibration suppression device from the vessel on the line;
and installing the vortex induced vibration suppression device from
the line to the exterior of the subsea structure, covering at least
a portion of an outside surface of the subsea structure.
[0015] Advantages of the invention may include one or more of the
following:
[0016] improved systems and methods for suppressing VIV;
[0017] systems and methods for suppressing VIV that do not suffer
from the disadvantages of the prior art;
[0018] systems and methods for providing VIV suppression devices to
structures, and for improved installation systems and methods for
the VIV suppression devices; and/or
[0019] systems and methods of installing VIV suppression devices
with fewer trips required to the surface.
BRIEF DESCRIPTION OF THE FIGURES
[0020] FIG. 1 illustrates a structure subject to a current.
[0021] FIGS. 2a-2e illustrate a system to install suppression
devices on an underwater structure.
[0022] FIGS. 3a-3b illustrate a fairing system being installed
around a structure.
DETAILED DESCRIPTION
[0023] Referring now to FIG. 2a, system 200 is illustrated. System
200 includes surface structure 202 near the surface of the water,
which is attached to connector member 204. Connector member 204 is
also connected to subsurface structure 203 near seafloor 208.
Exterior to connector member 204 near seafloor 208, collar 220 has
been installed. Vessel 222 is also near the surface of the water,
which is connected to collar 220 by one or more lines 224. Instead
of collar 220, lines 224 can be connected to structure 202 by any
suitable method, such as tying the line 224 near a joint of
structure 202, near a flange of structure 202, welding or gluing
line 224 to structure, or other suitable means as are known in the
art.
[0024] Referring now to FIG. 2b, fairings 214 have been lowered
from vessel 222 towards collar 220 along line 224. Fairings 214 act
to reduce drag and/or vortex induced vibration acting on connector
member 204 due to current 210. Fairings 214 may be heavier than
water so that they sink towards collar 220. Fairings may be
attached to each other with connectors 216.
[0025] Referring now to FIG. 2c, vessel 222 is moved towards
surface structure 202 so that fairings 214 and line 224 move closer
to connector member 204.
[0026] Referring now to FIG. 2d, subsurface vessel 230 with
attachment mechanism 232, for example arms, to grip fairings 214.
Subsurface vessel 230 is used to install fairings 214 about
connector member 204.
[0027] Referring now to FIG. 2e, line 224, subsurface vessel 230
and vessel 222 have been removed after the completion of fairings
214 about connector member 204. Fairings 214 may be heavier than
water so that they sink towards collar 220. Alternatively, fairings
214 may be lighter than water so that they float towards another
collar (not shown).
[0028] Referring now to FIG. 3a, fairing 314 is illustrated.
Fairing 314 may be installed about structure 304. Fairing 314 is
biased to a closed position, for example by a spring or by an
elastic material. Fairing 314 includes member 316, which keeps
fairing 314 from closing. Fairing 314 includes connection
mechanism, for example a male member 318a which can be received
within and lock within a female member 318b. Fairing 314 includes
two line guides 320a and 320b. Line guides 320a and 320b each can
receive a line to lower fairing 314 to a desired location along
structure 304, and to maintain the desired orientation of fairing
314 relative to structure 304, for example the opening of fairing
314 towards structure 304.
[0029] In operation, fairing 314 moves towards structure 304 as
shown by the arrow, so that structure 304 disables member 316, and
fairing 314 closes due to biasing force.
[0030] When fairing 314 closes, male member 318a is locked within
female member 318b, as shown in FIG. 3b.
[0031] A space may be defined between the exterior of structure 304
and the interior of fairing 314, which allows fairing 314 to
weathervane with varying current directions.
[0032] One or more portions of the system may be or contain copper
to retard marine growth.
[0033] Fairings may be replaced with strakes, shrouds, wake
splitters, tail fairings, buoyancy modules, or other devices as are
known in the art. Suitable sleeves, suitable collars, and suitable
devices to install exterior to structures, and methods of their
installation are disclosed in U.S. patent application Ser. No.
10/839,781, having attorney docket number TH1433; U.S. patent
application Ser. No. 11/400,365, having attorney docket number
TH0541; U.S. patent application Ser. No. 11/419,964, having
attorney docket number TH2508; U.S. patent application Ser. No.
11/420,838, having attorney docket number TH2876; U.S. patent
application Ser. No. 60/781,846 having attorney docket number
TH2969; U.S. Patent Application Number 60/805,136, having attorney
docket number TH1500; U.S. Patent Application Number 60/866,968,
having attorney docket number TH3112; U.S. Patent Application
Number 60/866,972, having attorney docket number TH3190; U.S. Pat.
No. 5,410,979; U.S. Pat. No. 5,410,979; U.S. Pat. No. 5,421,413;
U.S. Pat. No. 6,179,524; U.S. Pat. No. 6,223,672; U.S. Pat. No.
6,561,734; U.S. Pat. No. 6,565,287; U.S. Pat. No. 6,571,878; U.S.
Pat. No. 6,685,394; U.S. Pat. No. 6,702,026; U.S. Pat. No.
7,017,666; and U.S. Pat. No. 7,070,361, which are herein
incorporated by reference in their entirety.
[0034] Suitable methods for installing fairings, collars, and other
devices to install exterior to structures, are disclosed in U.S.
patent application Ser. No. 10/784,536, having attorney docket
number TH1853.04; U.S. patent application Ser. No. 10/848,547,
having attorney docket number TH2463; U.S. patent application Ser.
No. 11/596,437, having attorney docket number TH2900; U.S. patent
application Ser. No. 11/468,690, having attorney docket number
TH2926; U.S. patent application Ser. No. 11/612,203, having
attorney docket number TH2875; U.S. Patent Application Number
60/806,882, having attorney docket number TH2879; U.S. Patent
Application Number 60/826,553, having attorney docket number
TH2842; U.S. Pat. No. 6,695,539; U.S. Pat. No. 6,928,709; and U.S.
Pat. No. 6,994,492; which are herein incorporated by reference in
their entirety.
[0035] The collars and/or fairings may be installed on the
connector member before or after the connector member is placed in
a body of water. The collars, fairings and/or other devices
exterior to the structure may have a clamshell configuration, and
may be hinged with a closing mechanism opposite the hinge, for
example a mechanism that can be operated with an ROV.
[0036] Collars may be placed between adjacent fairings, or between
every 2 to 10 fairings. The collar may be a copper ring.
[0037] Fairings may be provided with copper plates on their ends to
allow them to weathervane with adjacent fairings or collars.
Fairings may be partially manufactured from copper.
[0038] A biodegradable spacer may be placed between adjacent
fairings to keep them from binding and allow them to weathervane
after the spacer has degraded.
[0039] Illustrative Embodiments In one embodiment, there is
disclosed a system comprising a subsea structure beneath a body of
water, subject to a water current; a collar exterior to the subsea
structure, covering at least a portion of an outside surface of the
subsea structure; an installation vessel floating on the body of
water; a line connected to the collar and the installation vessel;
and one or more vortex induced vibration suppression devices
connected to the line, which have been lowered from the vessel to
be installed on the subsea structure. In some embodiments, the
subsea structure is selected from an umbilical, a tubular, a riser,
and a tendon. In some embodiments, the vortex induced vibration
suppression device comprises a fairing or a helical strake. In some
embodiments, the line comprises at least two lines, the votex
induced vibration suppression devices connected to the at least two
lines. In some embodiments, the vortex induced vibration
suppression devices are negatively buoyant in water. In some
embodiments, the vortex induced vibration suppression devices
comprise one or more shoulders adapted to interface with the collar
and/or other vortex induced vibration suppression devices. In some
embodiments, the system also includes a collar between two adjacent
vortex induced vibration suppression devices, the collar connected
to the line.
[0040] In one embodiment, there is disclosed a method, comprising
installing a subsea structure in a body of water, wherein the
subsea structure is subject to one or more water currents;
installing a collar exterior to the subsea structure, covering at
least a portion of an outside surface of the subsea structure;
connecting at least one line to the collar and to a surface vessel;
lowering at least one vortex induced vibration suppression device
from the vessel towards the collar on the line; and installing the
vortex induced vibration suppression device from the line to the
exterior of the subsea structure, covering at least a portion of an
outside surface of the subsea structure. In some embodiments, the
method also includes installing additional collars exterior to the
subsea structure, the collars adapted to retain the vortex induced
vibration suppression devices in an axial location along the subsea
structure. In some embodiments, the collar is installed on the
subsea structure before the subsea structure is installed in the
body of water. In some embodiments, the vortex induced vibration
suppression device is installed on the subsea structure with a
remotely operated vehicle (ROV). In some embodiments, the vortex
induced vibration suppression device comprises an automatic closing
mechanism. In some embodiments, the vortex induced vibration
suppression device is installed by moving the device adjacent to
the subsea structure to activate the automatic closing mechanism.
In some embodiments, connecting at least one line to the collar and
to a surface vessel comprises connecting at least two lines; and
lowering at least one vortex induced vibration suppression device
from the vessel towards the collar comprises lowering on the at
least two lines.
[0041] Those of skill in the art will appreciate that many
modifications and variations are possible in terms of the disclosed
embodiments, configurations, materials and methods without
departing from their spirit and scope. Accordingly, the scope of
the claims appended hereafter and their functional equivalents
should not be limited by particular embodiments described and
illustrated herein, as these are merely exemplary in nature.
* * * * *