U.S. patent application number 09/847018 was filed with the patent office on 2002-04-11 for tender for production platforms.
Invention is credited to Beato, Christopher Louis, Tein, Yi Suang David.
Application Number | 20020040671 09/847018 |
Document ID | / |
Family ID | 26931401 |
Filed Date | 2002-04-11 |
United States Patent
Application |
20020040671 |
Kind Code |
A1 |
Beato, Christopher Louis ;
et al. |
April 11, 2002 |
TENDER FOR PRODUCTION PLATFORMS
Abstract
A mooring and tender system comprising: a deck; a shape that
results in a combined environmental load of less than 1000 kips in
a 100-year extreme weather condition; a plurality of supports
connected to the deck; a plurality of pontoons connecting to the
supports, at least two hawsers for connecting the tender to a
production platform, each having adequate elasticity to accommodate
the wave frequency between the production platform and the tender,
and adequate stiffness to synchronize the mean and low frequency
movement between the production platform and the tender under an
environmental load produced during a storm having a designation of
up to a 10-year storm in the tendering position, connecting means
securing each hawser; a hawser guidance system; an at least 8-point
mooring system with each mooring lines consisting of: a first
length of steel wire rope; a length of polymer rope secured to the
first length of steel wire rope; a second length of steel wire rope
secured to the polymer rope; and means for creating global
equilibrium between the production platform's mooring means and the
at least 8 point mooring system of the tender.
Inventors: |
Beato, Christopher Louis;
(Missouri City, TX) ; Tein, Yi Suang David;
(Houston, TX) |
Correspondence
Address: |
Wendy K. Buskop
Buskop Law Group, P.C.
Suite 500
1717 St. James Place
Houston
TX
77056
US
|
Family ID: |
26931401 |
Appl. No.: |
09/847018 |
Filed: |
May 1, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60238177 |
Oct 5, 2000 |
|
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Current U.S.
Class: |
114/230.1 |
Current CPC
Class: |
B63B 1/107 20130101;
B63B 21/50 20130101; B63B 2001/128 20130101; B63B 35/44
20130101 |
Class at
Publication: |
114/230.1 |
International
Class: |
B63B 021/00 |
Claims
What is claimed is:
1. A semisubmersible tender with a lightship displacement less than
15,000 short tons for a deep draft cassion vessel (SPAR) used as a
production platform having a mooring system, comprising: a. a deck;
b. a shape that results in a combined environmental load of less
than 1000 kips within a 100-year extreme weather condition; c. a
plurality of supports, each with a rounded shape, connected to said
deck; d. a plurality of pontoons connected to said supports, each
pontoon being capable of ballast transfer; e. at least two hawsers
for connecting said tender to said SPAR, each hawser having a
length which is selected from the group: the length of the tender,
the tendering distance, the length of the SPAR, and combinations
thereof; and wherein said hawsers have adequate elasticity to
accommodate the wave frequency between the SPAR and the tender, and
adequate stiffness to synchronize the mean and low frequency
movements between the SPAR and the tender under an environmental
load produced during a storm having a designation of up to a
10-year winter storm in the tendering position, and wherein said
hawsers remain slack during a storm designed as at least a 10 year
storm for the tender in the tender standby position; f. connecting
means mounted on the tender securing a first end of each hawser; g.
a hawser guidance system for each hawser to direct each said hawser
to the SPAR; h. an at least 8 point mooring system for said tender;
and i. means for creating global equilibrium between the SPAR's
mooring system and said at least 8 point mooring system of said
tender.
2. The tender of claim 1, wherein said at least 8-point mooring
system further comprises: a. at least 8 anchors; b. at least 8
mooring lines, each line consisting of: a first length of steel
wire rope secured to each of said anchors; a length of polymer rope
secured to each of said first length of steel wire rope; a second
length of steel wire rope having a first and second end, and
wherein said first end is secured to said length of polymer rope
and said second end is secured to the tender; and wherein said
mooring line has adequate elasticity, stiffness and strength to
accommodate the load on said tender under an environmental load
produced by an up to a 10-year storm in the tendering position, and
further wherein said mooring lines have a strength to withstand the
environmental load produced by up to a 100-year extreme weather
condition when said tender is moved to a 100-year extreme weather
condition standby position;
3. The tender of claim 1, wherein the connecting means are hawser
winches.
4. The tender of claim 1, wherein the connecting means comprise a
hawser wire rope, which winds on a hawser winch.
5. The tender of claim 2, wherein said mooring lines are taunt.
6. The tender of claim 1, wherein said supports are rounded columns
connected in a ring pontoon design.
7. A semisubmersible tender with a lightship displacement of less
than 15,000 short tons for a tension leg production platform (TLP)
having at least one tether, and a mooring system, comprising: a. a
deck; b. a shape that results in a combined environmental load of
less than 1000 kips within a 100-year extreme weather condition
comprising: c. a plurality of supports each with a rounded shape
connected to said deck; d. a plurality of pontoons connecting said
supports, each pontoon being capable of ballast transfer; e. at
least two hawsers for connecting said tender to said TLP, each
hawser having a length which is selected from the group: the length
of the tender, the tendering distance, the length of the tension
leg production platform, and combinations thereof; and wherein the
hawsers have adequate elasticity to accommodate the wave frequency
between the TLP and the tender, and adequate stiffness to
synchronize the mean and low frequency movements between the TLP
and the tender under an environmental load produced during a storm
having a designation of up to a 10-year winter storm in the
tendering position, and wherein said hawsers remain slack during a
storm designated as at least a 10-year storm or greater for the
tender in the tender standby position; f. connecting means mounted
on the tender and securing a first end of each hawser; g. a hawser
guidance system for each hawser to direct each said hawser to the
TLP; h. at least one tensioning line for providing tension to said
hawsers from said production platform, and wherein said at least
one tensioning line is secured to said TLP on the side opposite the
tender; i. an at least 8 point mooring system for said tender; and
j. means for creating global equilibrium between the TLP's tethers,
tensioning line and mooring system, and said at least 8 point
mooring system of said tender.
8. The tender of claim 7, wherein said at least 8-point mooring
system further comprises: a. at least 8 anchors; b. at least 8
mooring lines, each line consisting of: a first length of steel
wire rope secured to each of said anchors; a length of polymer rope
secured to each of said first length of steel wire rope; a second
length of steel wire rope having a first and second end, and
wherein said first end is secured to said length of polymer rope
and said second end is secured to the tender; and wherein each said
mooring line has adequate elasticity, stiffness and strength to
accommodate load on said tender under an environmental load
produced by an up to a 10-year storm in the tendering position, and
further wherein said mooring lines have a strength to withstand the
environmental load produced by and up to 100-year extreme weather
condition when said tender is moved to a 100-year extreme weather
condition standby position.
9. The tender of claim 7, wherein the connecting means are hawser
winches.
10. The tender of claim 7, wherein the connecting means comprise a
hawser wire rope, which winds on a hawser winch.
11. The tender of claim 7, wherein said mooring lines are
taunt.
12. The tender of claim 7, wherein said supports are rounded
columns connected in a ring pontoon design.
13. A semisubmersible tender with a lightship displacement less
than 15,000 short tons for a compliant tower production platform
having a steel structure extending to the sea floor, comprising: a.
a deck; b. a shape that results in a combined environmental load of
less than 1000 kips within a 100-year extreme weather condition; c.
a plurality of supports each with a rounded shape connected to said
deck; d. a plurality of pontoons connecting said supports, each
pontoon being capable of ballast transfer; e. at least two hawsers
for connecting said tender to said compliant tower production
platform, each hawser having a length which is selected from the
group: the length of the tender, the tendering distance, the length
of the compliant tower production platform, and combinations
thereof; and wherein the hawsers have adequate elasticity to
accommodate the wave frequency between the compliant tower and the
tender, and adequate stiffness to synchronize the mean and low
frequency movement between the compliant tower and the tender under
an environmental load produced during a storm having a designation
of up to a 10-year winter storm in the tendering position, and
wherein said hawsers remain slack during a storm designated as at
least a 10-year storm for the tender in the tender standby
position; f. connecting means mounted on the tender and securing a
first end of each hawser; g. a hawser guidance system for each
hawser to direct each said hawser to the compliant tower; h. at
least one tensioning line for providing tension from said
production platform to said hawsers; i. an at least 8 point mooring
system for said tender; and j. means for creating global
equilibrium between the compliant tower and said at least 8 point
mooring system of said tender.
14. The tender of claim 13, wherein at least 8-point mooring system
tender further comprises: a. at least 8 anchors; b. at least 8
mooring lines, each consisting of: a first length of steel wire
rope secured to each of said anchors; a length of polymer rope
secured to each of said first length of steel wire rope; a second
length of steel wire rope having a first and second end, and
wherein said first end is secured to said length of polymer rope
and said second end is secured to the tender; and wherein said
mooring line has adequate elasticity, stiffness and strength to
accommodate the load on said tender under an environmental load
produced by up to a 10-year storm in the tendering position, and
further wherein said mooring lines have a strength to withstand the
environmental load produced by a 100-year extreme weather condition
when said tender is moved to a 100-year extreme weather condition
standby position;.
15. The tender of claim 13, wherein said compliant tower further
comprises at least one tensioning line.
16. The tender of claim 13, wherein the connecting means are hawser
winches.
17. The tender of claim 13, wherein the connecting means comprise a
hawser wire rope, which winds on a hawser winch.
18. The tender of claim 13, wherein said mooring lines are
taunt.
19. The tender of claim 13, wherein said supports are rounded
columns.
20. A semisubmersible tender with a lightship displacement of less
than 15,000 short tons for a fixed leg production platform,
comprising: a. a deck; b. a shape that results in a combined
environmental load of less than 1000 kips in a 100-year extreme
weather condition; c. a plurality of supports each with a rounded
shape connected to said deck; d. a plurality of pontoons connecting
said supports, each pontoon being capable of ballast transfer, e.
at least two hawsers for connecting said tender to said fixed leg
production platform, each hawser having a length which is selected
from the group: the length of the tender, the tendering distance,
the length of the fixed leg production platform, and combinations
thereof; and wherein said hawsers have adequate elasticity to
accommodate the wave frequency between the fixed leg production
platform and the tender, and adequate stiffness to synchronize the
mean and low frequency movement between the fixed leg production
platform and the tender under an environmental load produced during
a storm having a designation of up to a 10-year winter storm in the
tendering position, and wherein said hawsers remain slack during a
storm designated as at least a 10 year storm for the tender in the
tender standby position; f. connecting means mounted on the tender
and securing a first end of each hawser; g. a hawser guidance
system for each hawser to direct each said hawser to the fixed leg
production platform; and h. an at least 8 point tender mooring
system for said tender; and i. means for creating global
equilibrium between the fixed leg production platform and said at
least 8 point mooring system of said tender.
21. The tender of claim 20, wherein said tender further comprises:
a. at least 8 anchors; b. at least 8 mooring lines, each consisting
of: a first length of steel wire rope secured to each of said
anchors; a length of polymer rope secured to each of said first
length of steel wire rope; a second length of steel wire rope
having a first and second end, and wherein said first end is
secured to said length of polymer rope and said second end is
secured to the tender; and wherein said mooring line has adequate
elasticity, stiffness and strength to accommodate the load on said
tender under an environmental load produced by an up to 10-year
storm in the tendering position, and further wherein said mooring
lines have a strength to withstand the environmental load produced
by up to a 100-year extreme weather condition, when said tender is
moved to a 100-year extreme weather standby position.
22. The tender of claim 20, wherein the connecting means are hawser
winches.
23. The tender of claim 20, wherein the connecting means comprise a
hawser wire rope, which winds on a hawser winch.
24. The tender of claim 20, wherein said mooring lines are
taunt.
25. The tender of claim 20, wherein said pontoons of said tender
are connected in a ring design.
26. A semisubmersible tender with a lightship displacement of less
than 15,000 short tons for a semisubmersible production vessel with
a mooring system, comprising: a. a deck, b. a shape that results in
a combined environmental load less than 1000 kips in a 100-year
extreme weather condition; c. a plurality of supports each with a
rounded shape, connected to said deck; d. a plurality of pontoons
connecting said supports, each pontoon being capable of ballast
transfer; e. at least two hawsers for connecting said tender to
said semisubmersible production vessel, each hawser having a length
which is selected from the group: the length of the tender, the
tendering distance, the length of the semisubmersible production
vessel, and combinations thereof; and wherein the hawsers have
adequate elasticity to accommodate the wave frequency between the
semisubmersible production vessel and the tender, and adequate
stiffness to synchronize the mean and low frequency movement
between the semisubmersible production vessel and the tender under
an environmental load produced during a storm having a designation
of up to a 10-year winter storm in the tendering position, and
wherein said hawsers remain slack during a storm designated as at
least a 10-year storm for the tender in the tender standby
position; f. connecting means mounted on the tender and securing a
first end of each hawser; g. a hawser guidance system for each
hawser to direct each said hawser to the semisubmersible production
vessel; h. an at least 8 point tender mooring system for said
tender; and i. means for creating global equilibrium between the
semisubmersible production vessel's mooring system and said at
least 8 point mooring system of said tender.
27. The tender of claim 26, wherein said at least 8-point mooring
system further comprises: a. at least 8 anchors; b. at least 8
mooring lines, each line consisting of: a first length of steel
wire rope secured to each of said anchors; a length of polymer rope
secured to each of said first length of steel wire rope; a second
length of steel wire rope having a first and second end, and
wherein said first end is secured to said length of polymer rope
and said second end is secured to the tender; and wherein said
mooring line has adequate elasticity, stiffness and strength to
accommodate load on said tender under an environmental load
produced by an up to a 10-year storm in the tendering position, and
further wherein said mooring lines have a strength to withstand the
environmental load produced by up to a 100-year extreme weather
condition, when said tender is moved to a 100-year extreme weather
condition standby position.
28. The tender of claim 26, wherein the connecting means are hawser
winches.
29. The tender of claim 26, wherein the connecting means comprise a
hawser wire rope, which winds on a hawser winch.
30. The tender of claim 26, wherein said mooring lines are
taunt.
31. The tender of claim 26, wherein said pontoons are connected in
a ring design.
32. A mooring and tender system for securing a tender to a
production platform, comprising: a. a semisubmersible tender for a
production platform having mooring means and having a lightship
displacement of less than 15,000 short tons, comprising: i. a deck;
ii. a shape that results in a combined environmental load of less
than 1000 kips in a 100-year extreme weather condition; iii. a
plurality of supports with a rounded shape connected to said deck;
iv. a plurality of pontoons connecting said supports, each pontoon
being capable of transverse ballast transfer and longitudinal
ballast transfer; v. at least two hawsers for connecting said
tender to said production platform, each hawser having a length
which is selected from the group: the length of the tender, the
tendering distance, the length of the production platform, and
combinations thereof; and wherein said hawsers have adequate
elasticity to accommodate the wave frequency between the production
platform and the tender, and adequate stiffness to synchronize the
mean and low frequency movement between the production platform and
the tender under an environmental load produced during a storm
having a designation of up to a 10-year storm in the tendering
position, and wherein said hawsers remain slack during a storm
designated as at least a 10-year storm for the tender in the tender
standby position; vi. connecting means mounted on the tender and
securing a first end of each hawser; vii. a hawser guidance system
for each hawser to direct each said hawser to the production
platform; viii. an at least 8-point mooring system for said tender
comprising: (a) at least 8 anchors; (b) at least 8 mooring lines,
each line consisting of: a first length of steel wire rope secured
to each of said anchors; a length of rope secured to each of said
first length of steel wire rope; a second length of steel wire rope
having a first and second end, and wherein said first end is
secured to said length of rope and said second end is secured to
the tender; and wherein each said mooring line has adequate
elasticity, stiffness and strength to accommodate load on said
tender under an environmental load produced by an up to a 10-year
storm in the tendering position, and further wherein said mooring
lines have a strength to withstand the environmental load produced
by up to a 100-year extreme weather condition when said tender is
moved to a 100-year extreme weather condition standby position; and
(c) means for creating global equilibrium between the production
platform's mooring means and said at least 8 point mooring system
of said tender.
33. The mooring and tender system of claim 32, wherein said tender
pontoons are constructed in the shape of a ring and said shape is
selected from the group: triangular, rectangular, square, and
triangular.
34. The mooring and tender system of claim 32, wherein the at least
8 point mooring system comprises a 7 line mooring system, and one
broken mooring line.
35. The mooring and tender system of claim 32, wherein the
transverse ballast transfer occurs at a rate in a range from at
least 30 to 300 gallons per minute.
36. The mooring and tender system of claim 32, wherein the
longitudinal ballast transfer occurs at a rate in a range of from
180 to 300 gallons per minute.
37. The mooring and tender system of claim 32, wherein said
pontoons are ballasted.
38. The mooring and tender system of claim 32, wherein said
pontoons have rounded edges.
39. The mooring and tender system of claim 32, wherein said
supports are round columns.
40. The mooring and tender system of claim 39, wherein shape
comprises between 3 and 12 columns.
41. The mooring and tender system of claim 32, wherein said
supports contain a member of the group comprising: ballast transfer
equipment, bulk storage tanks; drilling mud storage tanks; fluid
tanks; ballast control systems; mooring line storage reels,
transfer equipment for fluids in the designated tanks and
combinations thereof.
42. The mooring and tender system of claim 41, wherein said mooring
line storage reels are connected to winches disposed within said
supports, thereby lowering the center of gravity of said
tender.
43. The mooring and tender system of claim 32, wherein said length
of rope has an outer diameter between 4 and 10 inches.
44. The mooring and tender system of claim 32, wherein said length
of rope is a material selected from the group: polyester,
polypropylene, polyethylene, and combinations thereof.
45. The mooring and tender system of claim 32, wherein said hawsers
are made from a polyamide.
46. The mooring and tender system of claim 44, wherein said
polyamide is nylon.
47. The mooring and tender system of claim 32, wherein said
production platform is of a member of the group: a deep draft
cassion vessel (SPAR), a tension leg platform (TLP), a
semisubmersible production vessel, a fixed leg production platform
and a compliant tower production platform.
48. The mooring and tender system of claim 32, further comprising a
measurement system to record the exact distance and spacial
relationship between said tender and said production platform.
49. The mooring and tender system of claim 32, further comprising a
camera system which allows the tender, production platform,
hawsers, hawser guidance system, and related equipment to be
monitored.
50. The mooring and tender system of claim 32, further comprising a
monitoring system to analyze any variation in tension on the
connecting means.
51. The mooring and tendering system of claim 41, further
comprising mooring winch storage disposed in said supports to lower
the center of gravity of said tender.
52. The mooring and tendering system of claim 42, wherein said
fluid tanks contain sterile brine completion fluids.
53. The mooring and tendering system of claim 49, wherein said
hawser guidance system comprises a conical horn through which the
hawser line is passed.
Description
BACKGROUND OF THE INVENTION
[0001] Field of the Invention
[0002] This application claims the benefit of priority of
co-pending provisional application Ser. No. 60/238,177, filed in
the United States Patent and Trademark Office on Oct. 5, 2000.
[0003] This invention relates to a semisubmersible tender adapted
for facilitating servicing of off shore oil and natural gas
production platforms, subsea wells, and other subsea infrastructure
in water depths up to 10,000 feet.
[0004] The present invention specifically relates to a
semisubmersible tender which can be secured to different types of
production platforms, such as a tension leg platform (TLP), a deep
draft cassion vessel (SPAR), a fixed platform, a compliant tower, a
semisubmersible production vessel, or a floating vessel.
BACKGROUND OF THE INVENTION
[0005] It is very expensive to provide a production platform with
adequate space for all the drilling and completion equipment needed
to safely drill and complete a well and store drilling and
completion equipment and materials in an environmentally
conscientious manner, including drilling and completion risers,
casings, tubings and drilling and completion fluids. Tenders have
often been called into service to provide the required space needed
on a rig and/or platform during the initial drilling and completion
phase of an oil lease. Problems have traditionally existed in that
most tenders cannot be kept alongside a platform in a constant
spaced relationship during extreme weather without colliding with
the platform. Specifically, tenders have not been able to remain in
a connected capacity and avoid the risk of collision, enabling a
high operational weather window to the tender and rig, and still
endure the environmental load of up to a 10 year storm. See U.S.
Pat. Nos. 4,065,934, and 4,156,577, which are hereby incorporated
by reference on current tenders for platforms. Most tenders have
had to be completely towed away to a safe location in the case of a
tropical storm or extreme weather, which causes considerable
expense to the drilling contractor and/or customer.
[0006] Until the existence of this invention described herein, it
has been generally believed to be impossible to safely moor a
tender to a floating production platform in water depths exceeding
several hundred feet for long periods of time, exceeding one year
or any time during hurricane season.
[0007] The present invention has been created to provide up to
25,000 square feet of additional deck space and over 8000 bbls of
liquid storage capacity via a tender which is secured to the
production platform by a unique technique which enables the tender
to keep a constant distance from a production platform while
synchronizing its low and mean movement frequencies, which enables
the tender to follow the mooring watch pattern of the production
platform, such as a figure eight pattern, or elliptical pattern,
and to sustain without damage, the environmental load of wind,
current and wave forces of a 100-year cyclonic storm (such as a
hurricane) in the 100-year extreme weather standby position, and up
to a 10-year storm in a tendering position.
[0008] The invention is related to a device, which has significant
environmental and safety advantages over known systems and known
tenders.
[0009] The invention includes the semisubmersible tender, a tender
and mooring system which utilizes pre-set anchors, and a method of
tendering to a deep-water production platform for assisting in the
drilling and completion and recovery of oil and gas in weather that
can be up to a 10-year storm and maintaining a standby position in
weather up to a 100-year hurricane.
[0010] The present invention is directed to solving one or more of
the above problems by providing a tender for facilitating
installation operational support and removal of drilling and
completion equipment on a production platform while compensating
for platform motions in at least one plane.
SUMMARY OF THE INVENTION
[0011] The invention relates to a tender, and a mooring and tender
system for securing a unique semisubmersible tender to a production
platform. The semisubmersible tender has mooring means and a
lightship displacement of less than 15,000 short tons and
preferably between at least 8,000 and 15,000 short tons. The tender
comprises a deck; a shape that results in a combined environmental
load of less than 1000 kips in a 100-year extreme weather
condition; a plurality of supports connected to the deck; a
plurality of pontoons connecting the supports; at least two hawsers
for connecting the tender to the production platform, each hawser
having a length which is selected from the group: the length of the
tender, the tendering distance, the length of the production
platform, and combinations thereof; and wherein the hawsers have
adequate elasticity to accommodate the wave frequency motions
between the production platform and the tender, and adequate
stiffness and tension to synchronize the mean and low frequency
movement between the production platform and the tender under an
environmental load produced during a storm having a designation of
up to a 10-year storm in the tendering position.
[0012] This invention permits the tender to remain connected to the
platform yet the hawsers remain slack during a storm designated as
at least a 10-year storm for the tender in the tender standby
position. The tender further has connecting means securing a first
end of each hawser, and a hawser guidance system for each hawser to
direct each hawser to the production platform.
[0013] The tender uses an at least 8-point mooring system for the
tender which uses at least 8 anchors; at least 8 mooring lines,
with each line consisting of: a first length of steel wire rope
secured to each of the anchors; a length of polymer rope secured to
each of the first length of steel wire rope; a second length of
steel wire rope having a first and second end, and wherein the
first end is secured to the length of polymer rope and the second
end is secured to the tender. For the invention, each mooring line
has adequate elasticity, stiffness and strength to accommodate load
on the tender under an environmental load produced by an up to a
10-year storm in the tendering position, and further wherein the
mooring lines have a strength to withstand the environmental load
produced by up to a 100-year extreme weather condition when the
tender is moved to a 100-year extreme weather condition standby
position. The tender further has means for creating global
equilibrium between the production platform's mooring means and the
at least 8 point mooring system of the tender.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a top view of the moored tender secured to a
production platform known as a SPAR;
[0015] FIG. 2 shows mooring line orientations on a production
platform for a moored tender;
[0016] FIG. 3 is a perspective view of one embodiment of the tender
of the invention;
[0017] FIG. 4 is a perspective view of a ring design embodiment of
the tender of the invention;
[0018] FIG. 5 is a top view of a moored tender to a tension leg
platform;
[0019] FIG. 6 is a top view of a tender secured to a SPAR with
hawsers; and
[0020] FIG. 7 shows a top view of a first embodiment of hawser
guides.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] The semisubmersible tender of the present invention can be
used with a variety of production platforms, including both fixed
production platforms and floating production platforms. Platforms
that the tender can be tied to include deep draft cassion vessels
(SPARs), tension leg platforms (TLPs), compliant towers,
semisubmersible production vessels, or other floating ships or
vessels.
[0022] The invention relates to a tender and mooring system which
uses certain type of semisubmersible tender that can be attached to
a production platform and successfully eliminates the risk of
collision between the tender and the production platform during up
to a 10-year winter storm, thereby significantly improving the
health, safety and operating environment on an oil and natural gas
production platform and drilling rig while enabling simultaneous
drilling and production operations, to some extent, during that
weather condition.
[0023] The present invention has significant environmental
advantages over known systems of tendering. The present tender has
significant safety advantages over known systems as well.
[0024] The invention has significant health, safety and
environmental advantages, when used as compared to a platform rig
and jack-up rig; inherent risks of those rigs are reduced on an
event-by-event basis. Specifically:
[0025] a. The invention offers over 10 times the working deck space
than either a platform rig or a jack up unit, virtually eliminating
confined space logistical operations.
[0026] b. The operation of the tender requires only 1/5 to 1/3 of
the equipment to be placed on the production platform compared to
an API platform rig.
[0027] c. The invention is helpful because it does not require any
engines or exhaust systems to be placed on the production platform,
which therefore decreases the fire risk and blow-out risk
associated with oil and gas well operations.
[0028] d. The modular design, combined with the use of a
construction crane, mounted on the tender enables efficient and
safe mobilization and support operations; significantly reducing
the number of lifts required to initiate drilling and completion
operations on the platform as compared to an API platform rig.
[0029] e. There are 90% fewer people required to be housed and work
on the production platform itself, when the invention is used.
[0030] f. The unique invention's storage capacities enable much
more efficient logistical planning and virtually eliminate
nighttime logistical offloading or back loading which is where a
significant percentage of accidents have historically occurred.
[0031] g. The invention's mooring system (i) enables a predictable
operational weather window, matching or exceeding that of either a
platform rig or a jack up rig; (ii) virtually eliminates the risk
of collision damage during all operational events; (iii) enables
the unit to quickly evacuate the immediate platform area in case of
an emergency, and (iv) provide an ideal support unit to facilitate
rescue or emergency response operations during an emergency.
[0032] h. Zero discharge of drilling and completion fluids, drill
cuttings, spilled or uncontained leaks, and unprocessed water,
including rainwater.
[0033] The invention also relates to a mooring and tender system
for securing a tender to a production platform, comprising:
[0034] a. a semisubmersible tender for a production platform having
mooring means and having a lightship displacement of less than
15,000 short tons, comprising:
[0035] i. a deck;
[0036] ii. a shape that results in a combined environmental load of
less than 1000 kips in a 100-year extreme weather condition;
[0037] iii. a plurality of supports with a rounded shape connected
to the deck;
[0038] iv. a plurality of pontoons connecting said supports, each
pontoon being capable of transverse ballast transfer and
longitudinal ballast transfer;
[0039] v. at least two hawsers for connecting the tender to the
production platform, each hawser having a length which is selected
from the group: the length of the tender, the tendering distance,
the length of the production platform, and combinations thereof;
and wherein the hawsers have adequate elasticity to accommodate the
wave frequency between the production platform and the tender, and
adequate stiffness and tension to synchronize the mean and low
frequency movement between the production platform and the tender
under an environmental load produced during a storm having a
designation of up to a 10-year storm in the tendering position, and
wherein the hawsers remain slack during a storm designated as at
least a 10-year storm for the tender in the tender standby
position;
[0040] vi. connecting means mounted on the tender and securing a
first end of each hawser;
[0041] vii. a hawser guidance system for each hawser to direct each
the hawser to the production platform;
[0042] b. an at least 8-point mooring system for the tender
comprising:
[0043] ii. at least 8 anchors;
[0044] iii. at least 8 mooring lines, each line consisting of: a
first length of steel wire rope secured to each of the anchors; a
length of rope secured to each of the first length of steel wire
rope; a second length of steel wire rope having a first and second
end, and wherein the first end is secured to the length of rope and
the second end is secured to the tender; and wherein each the
mooring line has adequate elasticity, stiffness and strength to
accommodate load on the tender under an environmental load produced
by an up to a 10-year storm in the tendering position, and further
wherein the mooring lines have a strength to withstand the
environmental load produced by up to a 100-year extreme weather
condition when the tender is moved to a 100-year extreme weather
condition standby position; and
[0045] iv. means for creating global equilibrium between the
production platform's mooring means and the at least 8 point
mooring system of the tender.
[0046] Referring now to FIG. 1, the tender 10 can be moored with at
least 8 mooring lines, 12, 14, 16, 18, 20, 22, 23 and 24. It is
contemplated that the mooring system of the invention can be
installed by first placing anchors in the sea floor, then attaching
mooring lines to the anchors, placing a buoy on the line secured to
the anchors, and then attaching the mooring line to the tender. A
particular embodiment for a tender's mooring system in relation to
a SPAR's mooring system is shown in FIG. 1.
[0047] For a SPAR 11, the tender 10 is secured to the SPAR 11,
using at least two hawsers, 32 and 34. This production platform is
also known as a deep draft cassion vessel. It should be noted that
a SPAR is typically moored with 12 to 16 mooring lines in four
cluster groups. FIG. 1 shows mooring lines 36a, 36b, 36c, 38b, 38c,
40a, 40b, 40c, 42a, 42b and 42c. This invention enables a SPAR to
be used as a drilling and production platform without significantly
increasing its size or cost, yet maintaining a high safety factor
for the production crew on board the SPAR, while protecting the
environment from harmful discharge.
[0048] FIG. 2 shows one example of the invention, where tender 10
is moored to the seafloor 50 through 6000 ft of water. Two mooring
lines 12 and 14 are shown secured to anchors on the sea floor 50. A
vertical loaded anchor 44 is used to moor the tender to the sea
floor. An example of such an anchor is a plate anchor, as described
in U.S. Pat. No. 6,122,847 and hereby incorporated by reference.
Alternatively, a piled anchor which is suction installed can be
used as the mooring anchor for the tender. The anchor 44 is secured
to one end of mooring line 14. A second anchor 46 is shown secured
to a second end of mooring line 12. On the other end, is secured to
a first length of steel rope 48, which is termed "anchor wire
rope."
[0049] In 6000 feet of water where a tender is moored to a SPAR,
the length of the anchor wire rope 48 is typically 1500 feet and
has a preferred outer diameter of 41/2 inches. The breaking
strength of anchor wire rope 48 is at least 2061 kips.
[0050] Anchor wire rope 48 is connected to a polymer rope 52, which
is most preferably a polyester rope made by Marlow, UK, or
Whitehill Manufacturing Corporation, U.S.A., or CSL (Cordvaia) of
Saul Leopoldo, Brazil. The length of the polymer rope 52 for
6000-feet of water is preferably 5,500 feet using an outer diameter
of 7.1 inches. The outer diameter of polymer rope 52 can vary
between 4 and 10 inches and still remain usable in this invention.
The breaking strength of the polymer rope 52 should be at least
2300 kips. A buoy 54, preferably having a net buoyancy of at least
40 kips and up to 100 kips, is secured to polymer rope 52 to keep
mooring line 12 off the sea floor 50.
[0051] In an embodiment where the water is 1760 feet, it is
contemplated that the mooring system can use pre-installed
segments, which include suction installed pile anchors or high
performance drag embedment anchors. For 1760 feet of water, the
anchor wire rope 48 is preferably 500 to 550 feet long with an
outer diameter of about 4 and 7/8.sup.th inches and a six-strand
construction. Connected to the anchor wire rope 48 of this water
depth embodiment is rope 56, which preferably is about 3100 feet
long and has a 71/2-inch OD, with a parallel strand construction. A
second, a buoy, having 40-kip net buoyancy can be secured to the
rope 56.
[0052] Rope 56 is connected at the end opposite the polymer rope to
a second steel rope 60, known in the industry as a "vessel wire
rope." For a 1760-foot water depth embodiment, this rope is
approximately 3000 feet long having an outer diameter of 4 and 7/8
inches. The breaking strength of the rope is at least 2300 kips
with a 1{fraction (1/16)} inch corrosion allowance. A preferred
vessel wire rope 60, can be obtained from Diamond Blue. Vessel wire
rope 60 is secured at the other end to tender 10. A high strength
six-strand construction is preferred for the vessel wire rope
60.
[0053] It should be noted that even though polyester rope is the
most preferred for polymer rope 52, other polymer ropes are
contemplated as usable herein, including but not limited to
polypropylene rope, polyethylene rope, polybutylene rope and
combinations thereof. The construction of the polymer rope can
range from parallel strand construction to wound multiple strand
constructions as is generally know in the maritime industry. It
should also be noted that at least 8 mooring lines are preferred
but 7 lines with one broken can be used. In other embodiments, more
mooring lines can be used. When 9 or more mooring lines are used
instead of 8 mooring lines, the individual thickness of the mooring
lines can be reduced while maintaining the required design safety
factors for the tender.
[0054] FIG. 3 shows a view of the semisubmersible tender 10 having
8 supports 56, 58, 68, 70, 72, 74, 76, and 78. In the most
preferred embodiment, the supports are structures with rounded
edges or round shapes, such as columns. The deck is attached to
these columns. In this Figure a rectangular shape is shown, but the
tender is most preferably constructed in a ring design, with
between 3 to 12 column supports. In FIG. 3, the 8 rounded supports
are shown, as four large rounded supports as 56, 58, 68 and 70, and
four smaller rounded supports are shown as 72, 74, 76 and 78. At
least two pontoons 80 and 82 are shown in this embodiment. Each is
capable of being ballasted. Preferably, each pontoon, if used, has
rounded edges. In one embodiment, each pontoon is designed to have
a stem and bow. Secured to the pontoons in one usable embodiment,
are at least two buoyant transverse cross members 84 and 86, which
are generally kept void but may be capable of being quickly
ballasted. The pontoons are capable of transferring ballast quickly
between pontoons and columns. The contemplated quick transverse
ballast transfer is between about 30 and 300 gallons per minute,
and preferably, 80 to 300 gallons per minute, and the quick
longitudinal ballast transfer is between about 180 and 300 gallons
per minute.
[0055] FIG. 4 shows an alternative construction of the tender using
cross members 64, 66 and 68 engaging corresponding pontoons
connected so as to form a triangular shape for the resultant
tender. Crane 60 can be placed on the deck 54 which is supported by
the columns disposed on the pontoons and supported by the cross
members. It should be noted that it is within the scope of the
invention that this tender be self propelled or towed on a body of
water to a position near a production platform.
[0056] The semisubmersible tender of the invention preferably has
at least 3 and up to 12 supports with a rounded shape. In the most
preferred embodiment, the pontoons of the invention are assembled
in a triangular ring design, though circular, square or rectangular
shape will also work.
[0057] The tender is constructed to have a size and shape which
results in a combined environmental load of less than 1,000 kips
within a 100-year extreme weather condition, such as a hurricane
when one of 8 mooring lines is damaged and when the tender is in
the standby position. The tender shape results in a combined
environmental load of less than 600 kips within a 10-year storm
when secured to a production platform, like a SPAR, with one
mooring line damaged, in a tendering position with 40 to 60 feet of
consistent clearance between the tender and the production
platform.
[0058] In a preferred embodiment, it is contemplated that the
supports can contain traditional and non-traditional items. In one
embodiment it is contemplated that when certain non-traditional
items are used, they can be used to lower the center of gravity of
the tender for additional stability. These items can include filled
tanks of sterile brine completion fluids and ballast transfer
equipment, bulk storage tanks, drilling and completion storage
tanks, fluid tanks; ballast control systems; mooring line storage
reels, transfer equipment for fluids in the designated tanks and
combinations thereof. Specifically, the mooring storage line reels
are used, they can be connected to winches within the supports,
thereby lowering the center of gravity of the tender. The mooring
winch storage can also be disposed in the supports to lower the
center of gravity of the tender.
[0059] The tender and mooring system is capable of maintaining a
safe clearance between the platform and the tender under the
maximum operating conditions, specifically, up to the 10-year
winter storm and up to the 10-year loop current condition in the
Gulf of Mexico. For a SPAR, this is achieved by the use of dual
mooring hawsers, which are tensioned to 100-kips to 150-kips each
by adjusting the line tensions of the SPAR and the tender spread
mooring legs while keeping the vessels at their designated
locations. The designated location for the SPAR is directly above
the subsea wellheads with the tender generally being kept between
50 ft and 80 ft from the SPAR.
[0060] Safe distance is maintained between the SPAR and the tender
at all times, thus eliminating vessel collision risk. The use of
tensioned hawsers assures synchronized mean and low frequency
movement between the two vessels, should any mooring line break,
the two floating vessels would move apart, thus increasing the
distance between the two units.
[0061] When a major storm approaches the tender and mooring system,
the hawsers will be slackened. The tender will be pulled away from
the production platform to a safer distance, a tender standby
position, due to the greater tension in the tender's bow mooring
lines. If required, the tender can be winched further away from the
production platform using its at least 8 point mooring system.
[0062] The tender will be further winched away from the SPAR to an
extreme weather event standby position in the event of an imminent
tropical storm or hurricane. The tender mooring is designed to
withstand the 100-year hurricane and yet maintain a safe clearance
with the production platform under a scenario where all mooring
lines are intact or if one mooring line is damaged.
[0063] FIG. 5 shows a preferred mooring line orientation for the
semisubmersible tender when secured to a TLP. Mooring line 100 is
oriented about 45 degrees from mooring line 102 when in the
hurricane standby position. FIG. 5 shows the tender's mooring lines
100, 101, 102, 103, 104, 105, 106, and 107. In the preferred
embodiment, all mooring lines are kept tensioned. The TLP's
auxiliary mooring lines or tension lines are 108 and 110. These
tension lines are used as a means to create global equilibrium
between the TLP and the tender. The hawsers are 112 and 114.
Support columns for the TLP are 116,118,120, and 122.
[0064] For a TLP, the tender mooring system will consist of 8
spread-mooring legs and two mooring hawsers connecting the tender
to the TLP. The TLP's position will be maintained by the use of two
spread-mooring legs attached to the TLP on the opposite tender
spread-mooring legs.
[0065] It should be noted that the tender has a lightship
displacement of no more than 15,000 short tons and preferably is in
the range of 8000 to 15,000 short tons, preferably 12,000 short
tons.
[0066] The present invention additionally has zero discharge, which
is a significant improvement over most current drilling and
completion tenders, mobile offshore drilling units (MODU's) and API
platform rigs in order to protect the environment.
[0067] In FIG. 6, tender 10 is shown connects to the production
platform 11 using at least two hawsers 32 and 34, with each hawser
being constructed from a polyamide, such as a nylon.
[0068] The hawser line preferably has a diameter of 5.5 inches. The
diameter of the hawser can range from 3 to 7 inches and the length
can vary depending on the type of production platform the tenders
are tied to as well as the anticipated severe weather conditions;
each hawser having a length which is selected from the group: the
length of the tender, the tendering distance, the length of the
semisubmersible production vessel, and combinations thereof. The
hawser is preferably rated for up to 1000 kips breaking
strength.
[0069] Hawsers are connected to a connecting means such as hawser
winches, which are capable of variable payout for connecting the
tender to a production platform, such as a tension leg platform.
Alternatively, the connecting means are a hawser wire rope that
winds on a hawser winch. A preferred nylon hawser is from fibers
made by the E. I. DuPont Company of Wilmington, Del. The hawser
line should have adequate elasticity to accommodate the different
wave frequency movement between tender and production platform, but
are stiff enough so that tender and production platform mean and
low frequency movements can be synchronized thereby enabling the
tender to move in substantially identical mooring watch pattern
shapes, such as a figure eight mooring watch pattern or an
elliptically shaped mooring watch pattern.
[0070] In a preferred embodiment, hawsers have adequate elasticity
to accommodate the wave frequency movements between the production
platform and the tender, and adequate stiffness to synchronize the
mean and low frequency movement between the production platform and
the tender under an environmental load produced during a storm
having a designation of up to a 10-year storm in the tendering
position, and wherein said hawsers remain slack during a storm
designated as at least a 10-year storm for the tender in the tender
standby position. The tender can synchronize between the mean and
low frequency excursions, which have greater than 50 second
periods, by tensioning the hawsers. The inventive system allows the
tender to accommodate the relative wave frequency motions which can
range from 3 to 25 seconds in full cycle period by optimizing the
elasticity of the mooring lines. The invention enables a safe
clearance, of at least 35 feet to be maintained between the
production platform and the tender during all possible tendering
conditions, whether or not one mooring line is damaged or all lines
are intact.
[0071] A usable safe operating distance is considered between 35
and 80 feet, and preferably at least 40 and more typically, 50 to
60 feet of safe clearance in normal weather and current which can
be a sudden squall, a 1-year winter storm and a 1-year loop
current.
[0072] The unique tender preferably has a size with at least 15,000
square feet and up to about 40,000 square feet of deck space most
preferably, 25,000 square feet.
[0073] The tender has three positions relative to the production
platform: (i) extreme weather standby (for cyclone storms); (ii)
tender standby for weather conditions of 10-year storms, or
greater; and (iii) operating tender for weather conditions up to a
10-year storm. It is possible there may be a benign weather
condition position as well, which could be closer than 35 feet.
[0074] When in the extreme weather standby mode, the hawsers are
slacked, then the hawsers are then released and the tender is
winched away to a safe distance so that no collision occurs between
the production platform and the tender. This extreme weather
standby mode is used in not only the 100-year winter storm, but in
a 100-year hurricane or when a 100-year loop current causes severe
current, wave, and related weather conditions. The safe clearance
distance maintained by the tender in the extreme weather tender
standby mode is preferably at least 200 feet for the 100-year
winter storm, and at least 500 feet for the 100-year hurricane and
up to 1000 feet when moored in extremely deep water.
[0075] For the tender standby mode, such as in weather which is
greater than a 10-year storm, the tender is still connected to the
platform with the hawsers slack, but the tender is maintained at a
distance of between about 150 and 350 feet.
[0076] In the operating tender mode, the clearance between the
tender and the platform is a relatively constant 50 to 60 feet.
[0077] It should be noted that it is preferred that, the mooring
lines conform to API standard RP-2SK.
[0078] The tender supports can have a variety of uses, for example,
as bulk storage tanks, which can contain barite, cement, or
bentonite. Another use for the columns is to contain sterile
completion fluids or base drilling and completion fluids. The tanks
can hold completion fluids such as calcium chloride, zinc bromide
or potassium chloride.
[0079] FIG. 7 shows as horn 300 is construction to reduce friction
on the hawsers 32 or 34, enabling successful slackening of the
hawsers or tensioning of the hawsers with minimal friction impact
on the lines. These conical horns are of a bullhorn style, with the
largest portion of the horn facing the stern of the tender, and the
narrow portion facing the bow. The radius of curvature of the horn
should be at least eight times the diameter of the hawser to ensure
the hawser is not damaged during use, preferably 10 times the
hawsers diameter. The horns are preferably of steel with a treated
interior surface to minimize the coefficient of friction between
the guide itself and the hawsers to minimize the frictional wear or
damage of the hawser. Hawser 32 passes through the center of the
horn 300.
[0080] The tender has additional hawser guidance elements for the
hawser lines. Rounded pad eyes are secured to the underside of the
tender hull and the hawsers pass through the pad eyes to a wire,
which is connected to a winch on the bow of the tender. The purpose
of these pad eyes is to support the hawser when slack, preventing
the hawsers from being damaged. The purpose of the wire and wire
winch is to eliminate the need for the hawser to be wound on a
winch driver, passing through sheaves, which would damage the
hawser. When the tender moves to the tender standby position, the
wire is simply paid off of the wire hawser winches. The other end
of hawser is connected to the production platform using a pad eye
or some other similar kind of attached device.
[0081] The mooring and tender system further contemplates having on
the tender or otherwise using a measurement system to record exact
distance and spacial relationship between the tender and the
production platform. It also contemplates using a camera system,
which allows the tender, production platform, hawsers, hawser
guidance system and related equipment to be monitored. Finally, the
tender may have installed on it, or the system may include, a
monitoring system to analyze any variations in tension on the
connecting means of the tender.
[0082] The hawser winches for the tender are preferably ones with
drums having a capacity of at least 600 feet of 3-inch wire rope.
The winches preferably have a pull rating of 100,000 lbs@28 fpm.
The drums preferably have brakes, which are spring set and air
release band types rated at 600,000 lbs. The winch power is
preferably 100 hp using an AC motor with disk brakes and variable
frequency drive. The drum preferably has a 45-inch root diameter
with 60-inch long size for single layer operation. In the preferred
embodiment, the winch rope is connected to the hawser, then the
desired pre-tension is exerted by the winch motor. At this point
the winch drum brakes is set. If the hawser line pull exceeds the
brake rating (600,000 lbs), rope will pull off the drum until
equilibrium is re-established. Any readjustment to the
length/tension will be accomplished manually.
[0083] More specifically, the invention relates to a
semisubmersible tender with a lightship displacement less than
15,000 short tons for a deep draft cassion vessel (SPAR) used as a
production platform having a mooring system.
[0084] The vessel can be connected to a wide varsity of production
platforms. If connected to a deep draft cassion vessel, such as a
SPAR, it comprises:
[0085] a. a deck;
[0086] b. a shape that results in a combined environmental load of
less than 1000 kips within a 100-year extreme weather
condition;
[0087] c. a plurality of supports, each with a rounded shape,
connected to said deck;
[0088] d. a plurality of pontoons connected to said supports, each
pontoon being capable of ballast transfer;
[0089] e. at least two hawsers for connecting said tender to said
SPAR, each hawser having a length which is selected from the group:
the length of the tender, the tendering distance, the length of the
SPAR, and combinations thereof; and wherein said hawsers have
adequate elasticity to accommodate the wave frequency between the
SPAR and the tender, and adequate stiffness to synchronize the mean
and low frequency movements between the SPAR and the tender under
an environmental load produced during a storm having a designation
of up to a 10-year winter storm in the tendering position, and
wherein said hawsers remain slack during a storm designed as at
least a 10 year storm for the tender in the tender standby
position;
[0090] f. connecting means mounted on the tender securing a first
end of each hawser;
[0091] g. a hawser guidance system for each hawser to direct each
said hawser to the SPAR;
[0092] h. an at least 8 point mooring system for said tender;
and
[0093] i. means for creating global equilibrium between the SPAR's
mooring system and said at least 8 point mooring system of said
tender.
[0094] The vessel is moored to the sea floor using an 8-point
mooring system. This mooring system preferably has: (a) at least 8
anchors; and (b) at least 8 mooring lines, each line consisting of:
a first length of steel wire rope secured to each of said anchors;
a length of polymer rope secured to each of said first length of
steel wire rope; a second length of steel wire rope having a first
and second end, and wherein said first end is secured to said
length of polymer rope and said second end is secured to the
tender; and wherein said mooring line has adequate elasticity,
stiffness and strength to accommodate the load on said tender under
an environmental load produced by an up to a 10-year storm in the
tendering position, and further wherein said mooring lines have a
strength to withstand the environmental load produced by up to a
100-year extreme weather condition when said tender is moved to a
100-year extreme weather condition standby position.
[0095] For the TLP embodiment, the tender further comprises:
[0096] a. a deck;
[0097] b. a shape that results in a combined environmental load of
less than 1000 kips within a 100-year extreme weather condition
comprising:
[0098] i. a plurality of supports each with a rounded shape
connected to said deck;
[0099] ii. a plurality of pontoons connecting said supports, each
pontoon being capable of ballast transfer;
[0100] iii. at least two hawsers for connecting said tender to said
TLP, each hawser having a length which is selected from the group:
the length of the tender, the tendering distance, the length of the
tension leg production platform, and combinations thereof; and
wherein the hawsers have adequate elasticity to accommodate the
wave frequency between the TLP and the tender, and adequate
stiffness to synchronize the mean and low frequency movements
between the TLP and the tender under an environmental load produced
during a storm having a designation of up to a 10-year winter storm
in the tendering position, and wherein said hawsers remain slack
during a storm designated as at least a 10-year storm or greater
for the tender in the tender standby position;
[0101] iv. connecting means mounted on the tender and securing a
first end of each hawser;
[0102] v. a hawser guidance system for each hawser to direct each
said hawser to the TLP;
[0103] vi. an at least 8 point mooring system for said tender;
and
[0104] vii. means for creating global equilibrium between the TLP's
tethers, tensioning line and mooring system, and said at least 8
point mooring system of said tender.
[0105] If a compliant tower production platform is used, the tender
comprises:
[0106] a. a deck;
[0107] b. a shape that results in a combined environmental load of
less than 1000 kips within a 100-year extreme weather
condition;
[0108] c. a plurality of supports each with a rounded shape
connected to said deck;
[0109] d. a plurality of pontoons connecting said supports, each
pontoon being capable of ballast transfer;
[0110] e. at least two hawsers for connecting said tender to said
compliant tower production platform, each hawser having a length
which is selected from the group: the length of the tender, the
tendering distance, the length of the compliant tower production
platform, and combinations thereof; and wherein the hawsers have
adequate elasticity to accommodate the wave frequency between the
compliant tower and the tender, and adequate stiffness to
synchronize the mean and low frequency movement between the
compliant tower and the tender under an environmental load produced
during a storm having a designation of up to a 10-year winter storm
in the tendering position, and wherein said hawsers remain slack
during a storm designated as at least a 10-year storm for the
tender in the tender standby position;
[0111] f. connecting means mounted on the tender and securing a
first end of each hawser;
[0112] g. a hawser guidance system for each hawser to direct each
said hawser to the compliant tower;
[0113] h. an at least 8 point mooring system for said tender;
and
[0114] i. means for creating global equilibrium between the
compliant tower and said at least 8 point mooring system of said
tender.
[0115] Again, the tender can be moored in the same manner it was
moored for the SPAR and the TLP.
[0116] The tender can be used for a fixed leg production platform
and can comprise:
[0117] a. a deck;
[0118] b. a shape that results in a combined environmental load of
less than 1000 kips in a 100-year extreme weather condition;
[0119] c. a plurality of supports each with a rounded shape
connected to said deck;
[0120] d. a plurality of pontoons connecting said supports, each
pontoon being capable of ballast transfer,
[0121] e. at least two hawsers for connecting said tender to said
fixed leg production platform, each hawser having a length which is
selected from the group: the length of the tender, the tendering
distance, the length of the fixed leg production platform, and
combinations thereof; and wherein said hawsers have adequate
elasticity to accommodate the wave frequency between the fixed leg
production platform and the tender, and adequate stiffness and
tension to synchronize the mean and low frequency movement between
the fixed leg production platform and the tender under an
environmental load produced during a storm having a designation of
up to a 10-year winter storm in the tendering position, and wherein
said hawsers remain slack during a storm designated as at least a
10 year storm for the tender in the tender standby position;
[0122] f. connecting means mounted on the tender and securing a
first end of each hawser;
[0123] g. a hawser guidance system for each hawser to direct each
said hawser to the fixed leg production platform; and
[0124] h. an at least 8 point tender mooring system for said
tender; and
[0125] i. means for creating global equilibrium between the fixed
leg production platform and said at least 8 point mooring system of
said tender.
[0126] The tender can be used for a tendering to another
semisubmersible production platform. In that embodiment, the tender
can comprise:
[0127] a. a deck,
[0128] b. a shape that results in a combined environmental load
less than 1000 kips in a 100-year extreme weather condition;
[0129] c. a plurality of supports each with a rounded shape,
connected to said deck;
[0130] d. a plurality of pontoons connecting said supports, each
pontoon being capable of ballast transfer;
[0131] e. at least two hawsers for connecting said tender to said
semisubmersible production vessel, each hawser having a length
which is selected from the group: the length of the tender, the
tendering distance, the length of the semisubmersible production
vessel, and combinations thereof; and wherein the hawsers have
adequate elasticity to accommodate the wave frequency between the
semisubmersible production vessel and the tender, and adequate
stiffness to synchronize the mean and low frequency movement
between the semisubmersible production vessel and the tender under
an environmental load produced during a storm having a designation
of up to a 10-year winter storm in the tendering position, and
wherein said hawsers remain slack during a storm designated as at
least a 10-year storm for the tender in the tender standby
position;
[0132] f. connecting means mounted on the tender and securing a
first end of each hawser;
[0133] g. a hawser guidance system for each hawser to direct each
said hawser to the semisubmersible production vessel;
[0134] h. an at least 8 point tender mooring system for said
tender; and
[0135] i. means for creating global equilibrium between the
semisubmersible production vessel's mooring system and said at
least 8 point mooring system of said tender.
[0136] The additional tensioning lines or tethers are an important
feature of the invention for tensioning and release of tension to
the hawsers.
[0137] It should be noted, that the invention contemplates that the
tender system would work with jack-ups and other types of rigs
besides those mentioned.
[0138] Variations can occur within the scope of this invention. For
example, it is contemplated that this 8-point mooring system for
the tender to a SPAR could be a damaged 8-point system, that is, a
7-line system with one broken line and still work within the scope
of the invention.
[0139] Turning to the construction of the tender the tender for
each platform, pontoons connecting the supports. These pontoons can
be connected to form a rectangular shape or a triangular shape.
Regardless of how the pontoons are connected, it is contemplated
that the ballast in the pontoons can move at a transverse ballast
rate of between 30 and 300 gallons per minute. It is also
contemplated that the ballast can be moved at a longitudinal
ballast transfer at a rate in a range of from 180 to 300 gallons
per minute
[0140] Further features and advantages of the invention will be
apparent from the specification and the drawing.
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