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GENERAL |
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Designation
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Xxxxxxxxx
TLP |
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Name |
Gotham |
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Country |
UK /
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Location |
LOI-
Details will be provided. North Sea Area |
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Water depth |
148 |
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Duty |
Drilling,
production, accommodation |
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Status of unit |
Production |
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Unit operator |
A UK Energy
Co. |
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Status |
Production
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Field |
Xxxxxxxxx |
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Type |
TLP |
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Operator |
A UK |
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Owner |
Gotham
Energy Co. and field partners |
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Design |
TLP
(Tension Leg Platform) |
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Engineering |
Brown &
Root/VO Offshore |
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Built/history |
Hull,
Highlands Fabricators, Nigg; topsides, piles, McDermott Scotland, Ardersier.
Constructed 1982-83 |
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Other main contractors |
Project
services, Bechtel; accommodation/helideck, Sea & Land Pipelines |
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Delivery |
Original Installation… on field July 1984
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Start of production |
6 August 1984
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Basic Description & Design |
The
platform consists of four main components: the deck structure, a single
three-level integrated deck containing the usual drilling and production
facilities; hull structure, a six-column semi-submersible structure
providing buoyancy and ballasting to maintain platform trim; mooring system,
comprising four sets of four vertical tethers running from mooring
compartments in the hull to piled and grouted foundation templates on the
seabed; and the well template, a 32-slot pre-installed template for
pre-drilling with a semisubmersible.
Conservative margins in the original design have allowed a subsequent
increase in payload capacity of some 2500 mt; part of this was used to
increase water injection capacity in 1991, and part is kept in reserve for
possible satellite tie-ins. The principals will be recondition the
platform as part of the sales agreement. |
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Field application |
The
original field location produced 34.5° API crude from Brent formation
sandstones at about 9700 ft; reserves are estimated at 200 mmbbls
recoverable, and peak production of 107,000 bopd was reached in December
1984. The TLP was the first application of the tension leg concept. It is
moored over a pre-installed and pre-drilled template. Oil was produced
through an export line to Sullom Voe via South Cormorant; gas was used for
platform power and any excess flared. |
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MAIN DIMENSIONS |
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Hull dimensions |
92m long x
74m wide overall |
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Topsides dimensions |
78m x 74m |
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Height |
Overall 277
m from seabed; 53.7 metres to main deck; 64.5 metres to weather deck |
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Weight |
Hull 22,400
mt; 47,400 mt total operating weight plus 1350 mt riser tension; 25,000 mt
topsides weight |
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Air gap |
31.5 metres |
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Columns |
65 m high;
4 x 17.2m diam. corner columns; 2 x 14.5m inner columns |
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Pontoons |
Connecting
pontoons between columns |
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Deck area |
5772 m2
each level |
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Draught |
30 metres
operational |
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Displacement |
61,580 mt |
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Other components |
BOP:
Hydraulic wellhead connector, 3 x 16 3/4" 5000 psi Cameron U ram preventers,
1 x 16 3/4" 5000 psi Hydril annular preventer; 500 psi Regan KFDS diverter |
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CAPACITIES, PROCESS |
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Process system |
A single
train system comprising two-stage separation plus a surge tank to remove the
small amount of solution gas, most of which is used for platform power;
excess gas is flared, although this is expected to occur only at the
beginning and the end of platform life; the original flotation cell system
has been replaced by Vortoil hydrocyclones for produced water treatment;
crude is metered and sent to the export pipeline |
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Crude oil |
110,000
bopd |
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Gas capacity |
Used for
power or flared |
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Produced water |
NK;
increased in 1991 |
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Water injection |
275,000
bwpd at 4000 psi |
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Gas injection/lift |
None |
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Other capacities |
32 well
slots |
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CAPACITIES, TANK |
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Crude storage |
None |
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CAPACITIES. VARIABLE LOAD |
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Main power |
2 x GEC Gas
Turbines EAS1 15960 KW each; 1 x Ruston TB 3400 KW; firewater pumps,
emergency generator and some rig power by diesel |
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Propulsion |
None |
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Mooring/jacking system |
MOORING
TETHERS: 16 x 260mm diameter with 75mm hollowed core; pretensioned to
approx. 816 mt each tether; max. operating tension 8100 mt; tethers
fabrication, Nissho Iwai TETHER ANCHORING: Tethers anchored to four mooring
templates, approx. 250 mt each; dimensions 15.244m square x 6m high; each
template piled with 8 piles, 84" diameter x 68m long x WT 50mm, 250 mt each,
driven 60m |
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Control systems |
Load and
ballast system by dual Ferranti Argus 700 GX computer system; central
production and safety monitoring, Ferranti |
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Riser system |
Export
riser 12.75"; drilling riser comprising 16.75" 5000 psi triple ram BOP and
annular preventer connected through upper and lower flex joints, riser and
slip joints to the subsea wellhead connector and template; production risers
comprising a wellhead connector, flex joint, 9.625" x 47 ppf x 100 ksi yield
riser pipe with modified integral buttress connections, 13.375" tensioner
spool, and surface wellhead; passive tension jacks maintain 100,000 lb
tension on each riser and can accommodate a vertical stroke of 6 ft, +/- 10°
riser top angle, +/- 5° yaw angle, and a tension variation of 40% over 6 ft
stroke |
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Sub sea systems |
WELL
TEMPLATE: Unitized template with 32 slots, including 4 slots used for
levelling; 350 mt; 29m x 12m; design, Vetco Offshore; fabrication, McDermott
Scotland; installation, Heerema |
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Capability |
Rated to
20,000 ft; conceptual and detailed design, Rig Design Services; major
drilling equipment, National Supply; rig-up, Dan-Smedvig |
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Derrick |
30 ft x 30
ft, rated to 1,000,000 lbs |
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Drawworks |
1600 hp |
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Rotary |
Conventional rotary; 1000 hp top drive |
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Mud pumps |
2 x 1600 hp
triplex |
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OTHER FACILITIES |
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Cranes |
2 x
Stothert & Pitt OS200, 50t; 1 x Liebherr BOS 15/350, 15t |
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Accommodation |
239;
normal crew around 200 |
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Helideck |
For Boeing
'Chinook' |
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Communications |
Tropo
system to Scousburgh via Murchison platform, Marconi; SOLAS and main narrow
band communications, Inspectorate EaE |
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Safety features |
Fire
detection & prevention systems, Wormald |
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Lifesaving |
Lifeboat
capacity 500 |
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OPERATING PARAMETERS |
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Design life |
20 years
(field life approx. 14 years) |
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Design criteria |
100 year
storm: 29.9m wave, period 17 sec, 2.5 knot current, 98 mph wind, all
impinging on platform from a 45° angle, give a max. horizontal excursion of
24m |
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Water depth m |
148 metres
at Xxxxxxxxx |
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Production limits |
None within
design criteria |
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PRODUCT EXPORT/DISPOSAL |
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Oil |
6 km x
12.75 pipeline to NW Xxxxxxxxx; trenched |
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 |
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Gas |
Originally
not exported; used for fuel or flared; 7.7 km x 6" gas
import line
laid 1997 |
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PRICE
OPTION 1.
Time of Delivery |
$120
MILLION. FOB SITE. (INCLUDES REFURBISHMENT. ) *
TO
PROCEED - LETTER OF INTENT to GLOBAL
CHARTER
RATE. $750,000 DAY RATE 5-20 YEAR CONTRACT
Delivery. 18 months
approximately.
Refurbishment will take approximately 14-16 Months
from Purchase.
Delivery Optional
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REGULATORY |
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Classification |
Lloyd's
Register |
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Certification/approvals |
Lloyd's
Register |
