U.S. patent application number 10/204811 was filed with the patent office on 2003-11-06 for method and apparatus for increasing floating platform buoyancy.
Invention is credited to Horne, Earl Wilson, Kyriakides, Andrew.
Application Number | 20030206772 10/204811 |
Document ID | / |
Family ID | 29270154 |
Filed Date | 2003-11-06 |
United States Patent
Application |
20030206772 |
Kind Code |
A1 |
Horne, Earl Wilson ; et
al. |
November 6, 2003 |
Method and apparatus for increasing floating platform buoyancy
Abstract
A floating platform for recovery of oil and gas from offshore
oil and gas fields includes a hull having a portion located
substantially below the water surface, and including a portion
thereof which extends above the water surface. The platform is
anchored to the seabed by one or more tendons secured to the base
of the hull and the seabed. The playload capacity of the floating
platform is increased without redesigning the structural design of
the hull by attaching a column extension or mounting a detachable
buoyancy module to the lower end of the hull for accomodating
changing platform pay load requirements.
Inventors: |
Horne, Earl Wilson;
(Houston, TX) ; Kyriakides, Andrew; (Houston,
TX) |
Correspondence
Address: |
NICK A NICHOLS
P O BOX 16399
SUGARLAND
TX
774966399
|
Family ID: |
29270154 |
Appl. No.: |
10/204811 |
Filed: |
December 23, 2002 |
PCT Filed: |
February 22, 2001 |
PCT NO: |
PCT/US01/06160 |
Current U.S.
Class: |
405/224 ;
114/265; 405/195.1; 405/204; 405/223.1 |
Current CPC
Class: |
B63B 21/502 20130101;
B63B 35/4406 20130101 |
Class at
Publication: |
405/224 ;
405/223.1; 405/195.1; 405/204; 114/265 |
International
Class: |
E02B 001/00; E02D
023/00 |
Claims
1. A floating platform including a hull supporting one or more
decks in a body of water above the water line, and anchor means
securing the hull to the seabed below the water line, the
improvement comprising buoyancy means secured to the lower end of
said hull for increasing the buoyancy of the platform for
supporting a greater payload or operating in a greater water depth
without redesigning the structural design of said hull.
2. The platform of claim 1 wherein said buoyancy means comprises a
column extension attached to the lower end of said hull.
3. The platform of claim 2 wherein said column extension includes
plumbing for connection with the ballast system of said floating
platform.
4. The platform of claim 1 wherein said buoyancy means comprises at
least one buoyancy module mounted to the lower end of said
hull.
5. The platform of claim 4 including one or more connectors mounted
on the periphery of the lower end of said hull and said buoyancy
module for securing said module to said hull.
6. The platform of claim 4 wherein said connectors include
cooperative connector means for releasably attaching said buoyancy
module to said hull.
7. The platform of claim 2 wherein said column extension includes
support means on the peripheral surface thereof for supporting one
or more risers or flow lines connected to said floating
platform.
8. The platform of claim 4 wherein said buoyancy module includes
support means on the peripheral surface thereof for supporting one
or more risers or flow lines connected to said floating
platform.
9. A method for increasing the payload capacity of a floating
platform without redesigning the structural design of the hull of
said platform, the method including the step of attaching an
extension on the lower end of the hull of said platform.
10. A method of increasing the payload capacity of a floating
platform without redesigning the structural design of the hull of
said platform, the method including the step of mounting a
detachable buoyancy module on the lower end of the hull of said
platform.
Description
BACKGROUND OF THE DISCLOSURE
[0001] The present invention relates generally to floating platform
systems for testing and producing hydrocarbon formations found in
deep (600-10,000 feet) offshore waters. More particularly, the
invention relates to a method and system for changing the buoyancy
of the floating platform to accommodate changes in platform payload
and water depth requirements without redesigning the platform
hull.
[0002] The exploration for oil and gas deposits in offshore waters,
and recovery of the oil and gas therefrom is very expensive. Large
capital expenditures are required and thus only large oil and gas
deposits justify such expenditures. Smaller oil and gas deposits
usually do not justify large capital investments and therefore are
deemed to be uneconomical to produce.
[0003] Various methods and offshore production systems have been
utilized to locate and recover offshore oil and gas deposits.
Production systems such as converted Mobile Offshore Drilling Units
("MODU") and Tendon Leg Platforms (TLP) are typically used in deep
waters. Even these systems, however, can be quite expensive to
manufacture and install.
[0004] There continues to be a need for improved platform and
drilling systems, particularly for use in deep waters, which would
justify the economic investment to produce even relatively small
oil and gas fields. Drilling and production platforms, such as
TLP's, are engineered for use in particular offshore environments
and to support a maximum payload. The specifications for the
platform are based on assumptions which may or may not prove to be
accurate once the platform is installed and in use for a period of
time. Other factors, such as the discovery of recoverable oil and
gas from adjacent deposits may alter the payload requirements for a
platform already in use. Thus, being able to increase the payload a
platform can support without redesigning the hull would be highly
desirable and significantly reduce the cost of producing offshore
oil and gas deposits. Cost reductions can also be had by
eliminating the need for completely redesigning the hull and node
structure of the platform to accommodate different payload
requirements. The buoyancy of a floating platform may be increased
by extending the column length of the platform rather than
redesigning the hull, thereby saving time and engineering costs
associated with redesigning the platform hull.
[0005] It is therefore an object of the present invention to
provide a floating platform adapted to support an increase in
payload capacity without redesigning the structural design of the
hull of the platform. The increase in payload capacity is
accommodated by attaching a column extension to the lower end hull
of the platform while in the fabrication yard.
[0006] It is another object of the present invention to provide a
floating platform whereby the payload capacity of the platform may
be increased after the platform is located in the filed. Such an
increase in payload capacity is provided by attaching a buoyancy
module to the platform hull rather than redesigning the hull and
node structure of the platform.
SUMMARY OF THE INVENTION
[0007] The present invention provides a floating platform for
recovery of oil and gas from offshore oil and gas fields. The
platform supports one or more decks above the water surface to
accommodate equipment for drilling and processing oil, gas and
water recovered from the oil and gas field. In a preferred
embodiment, the platform includes a hull having a portion located
substantially below the water surface, and including a portion
which extends above the water surface. The platform hull includes a
base and is anchored to the seabed by one or more tendons secured
to the base of the hull at one end thereof and to the seabed at the
opposite ends of the tendons. The payload carrying capacity of the
platform is increased without redesigning the structural design of
the platform hull by attaching a column extension to the bottom of
the hull of the platform.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] So that the manner in which the above recited features,
advantages and objects of the present invention are attained can be
understood in detail, a more particular description of the
invention briefly summarized above, may be had by reference to the
embodiments thereof which are illustrated in the appended
drawings.
[0009] It is noted, however, that the appended drawings illustrate
only typical embodiments of this invention and are therefore not to
be considered limiting of its scope, for the invention may admit to
other equally effective embodiments.
[0010] FIG. 1 is a side view of a floating platform anchored to the
seabed;
[0011] FIG. 2 is a side view of the floating platform of the
invention including a buoyancy extension attached to the bottom of
the hull of the platform;
[0012] FIG. 3 is a partial side view of an alternate embodiment of
the platform of the invention depicting a buoyancy module mounted
to the bottom of the hull of the platform;
[0013] FIG. 4 is a top plan view of the platform of the invention
shown in FIG. 3;
[0014] FIG. 5 is a partial exploded view of the connector means for
securing the buoyancy module of the invention to the hull of the
platform; and
[0015] FIG. 6 is a side view of the platform of the invention
illustrating riser or flow line support means mounted on the
buoyancy module of the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0016] Referring first to FIG. 1, the floating platform of the
invention is generally identified by the reference numeral 10. The
platform 10 includes a central column or hull 12 which provides
positive buoyancy and vertical support for the platform 10. One or
more decks 14 are supported on the hull 12 above the water surface
16. Drilling and/or production equipment necessary for the recovery
and processing of oil, gas and water recovered from the oil and gas
field are secured on the deck 14.
[0017] The hull 12 extends upward from the base or keel of the hull
12. The base node of the hull 12 includes pontoons 18 extending
radially outward from the hull 12. The platform 10 is anchored to
the seabed by tendons 20 secured at one end thereof to the pontoons
18 and at the opposite ends thereof to foundation piles (not shown
in the drawings) embedded in the seabed. The hull 12 provides
sufficient buoyancy to support the payload of the platform 10,
which payload includes the deck 14, drilling and/or completion
equipment, production facilities, production and drilling risers
and sufficient excess buoyancy to develop the tendon
pre-tension.
[0018] The platform 10 is designed for the environmental and depth
conditions at the offshore location of an oil and gas deposit of
interest. At other locations, other platforms may be required to
efficiently recover the oil and gas from other subsea deposits.
Such other platforms may be required to carry a greater payload
than the platform 10 is designed to support. The increased payload,
however, may be accommodated by increasing the buoyancy of the
platform 10. An increase in buoyancy may be accomplished by
extending the length of the hull 12 rather than redesigning the
structural design of the hull and base node structure of the
platform 10. Likewise, the payload requirements for a platform may
increase after installation, in which case a buoyancy module 32, as
shown in FIG. 3, may be mounted to the bottom of the hull 12 of the
platform 10.
[0019] Referring now to FIG. 2, the column extension 22 is a
relatively short cylindrical chamber having an outside diameter
approximately equal to the outside diameter of the hull 12. The
column extension 22 is welded to the bottom of the hull 12 at weld
23 at the fabrication or construction site of the platform 10.
[0020] Referring now to FIG. 3, an alternate embodiment of the
invention depicts a buoyancy module 32 mounted to the bottom of the
hull 12. In the embodiment of FIG. 3, the buoyancy module 32 is
added to the offshore platform 10 while it is located in the field.
to increase the payload capacity of the platform 10 so that
additional equipment may be installed on the deck of the platform
10 or so that the platform 10 may be installed at a deeper water
site. The buoyancy module 32, like the column extension 22 shown in
FIG. 2, is a relatively short cylindrical chamber having a diameter
approximately equal to the diameter of the hull 12. Mounting posts
24 secure the module 32 to the hull 12. The mounting posts 24 may
be welded or otherwise fixed to the hull 12 and module 32.
[0021] Alternatively, the mounting posts 24 may be pre-installed
about the periphery of the hull 12, by welding or other connection
means, so that the module 32 may be installed at a later time after
the platform 10 is anchored offshore, as required, to increase the
payload capacity of the platform 10. The buoyancy module 32, shown
in FIG. 3, is likewise provided with mounting posts 26 for
cooperating engagement with the posts 24 mounted on the hull 12. As
more clearly shown in FIG. 5, the mounting posts 24 are adapted to
be received or telescoped into the posts 26. Various connections
means, such as grout, mechanical connectors or welding, may be
employed to lock the post 24 and 26 together and thus secure the
buoyancy module 32 to the bottom of the hull 12. This manner of
connection has the added benefit of permitting the module 32 to be
more easily detached from the hull 12 in the event the payload
requirements of the platform 10 change and the buoyancy module 32
is no longer needed or to substitute a larger module in the event
greater buoyancy is required. Two or more modules 32 may also be
connected in piggy-back manner in vertical alignment with the hull
12 in the event additional buoyancy is required.
[0022] The column extension 22 and buoyancy module 32 may be
provided with the necessary plumbing, including a fill port 28 and
vent 30, for connection with the ballast system of the platform 10.
Additional riser hangers, such as porches 33, for hanging risers or
flow lines 34 therefrom, as shown in FIG. 6, may be installed on
the column extension 22 or module 32, as required.
[0023] The shape of the column extension 22 and module 32 is
depicted as a closed cylinder or plug for illustrative purposes. It
is understood that the extension 22 and module 32 may comprise
various shapes. If, for example, the hull 12 includes a moon pool,
the extension 22 and module 32 may be provided with an axial
passage for matching alignment with the profile of the moon pool.
The extension 22 and module 32 in such an arrangement would have a
shape or profile similar to a donut. Likewise, the extension 22 and
module 32 may include radial extensions or arms matching the
profile of the pontoons 18, which arms may be secured to the bottom
of the pontoons 18.
[0024] While one or more preferred embodiments of the invention has
been shown and described, other and further embodiments of the
invention may be devised without departing from the basic scope
thereof, and the scope thereof is determined by the claims which
follow.
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