Project Type
Compliant Piled Tower (CPT)
Location
Deepwater block 14, Angola
Water Depth
1,280ft
Total Height
1,680ft (512m) from sea floor to top of derrick
Project Phases
2
Operator
Cabinda Gulf Oil Co. Ltd. (Chevron) 31%
Partners
Agip Angola 20%, Sonangol 20%, Total Angola 20% and Petrogal Exploration 9%
Location
Benguela and Belize fields
Wells
30
Well Slots
40
Location
Lobito and Tomboco fields
Combined Production
200,0100b/d by 2008
Main EPIC Contract
Daewoo ($820m)
Topsides
Daewoo at Okpo, South Korea
Operating Weight
43,500t
Accommodation
157 berths
Contractor
Delta Engineering at Channelview, Texas
Other Engineering
Drilling template, piles, flare boom and helideck
Weight
1,600t+
Tower Base Section and Template
26,000t
Contractor
Kiewit Offshore
Top Section
8,000t
Contractor
Gulf Marine Fabricators
Foundation Piles
12
Weight
11,000t
Fabricated
Ingleside, Texas
Contractors
Subsea 7 ($270m) and Vecto Gray ($125m)
Drilling Rig
KCA / Deutag and National Oilwell Varco ($120m)
Drilling Depth
30,000ft
Hook Load
1.3mmlb
Draw Works
4,600hp
Top Drive
60,000lbft torque
Mud Pumps
3 x 2,200hp pumps rated to 7,500psi
Total Mud Volume
4,625bbl
Installation Vessel
Thialf
Maximum Lift
10,470t
The Benguela, Belize, Lobito, and Tomboco fields form the BBLT development. It lies in deepwater block 14 off Angola, in the lower Congo basin.
The block lies in 1,280ft of water covering 1,560 square miles. The $2.2bn development centres on the first Compliant Piled Tower (CPT) outside the Gulf of Mexico. The CPT measures approximately 512m (1,680ft) from the seafloor to the top of its derrick. This ranks it as the fifth tallest freestanding structure in the world, standing 212m (694ft) taller than the Eiffel Tower.
Block 14 is operated by Cabinda Gulf Oil Co. Ltd., a subsidiary of Chevron with 31%. The other partners are Agip Angola 20%, Sonangol 20%, Total Angola 20% and Portugal’s Petrogal Exploration 9%.
The work is being carried out in a two-phase programme. The first phase consists of the Benguela and Belize developments. It is a compliant piled tower supporting an integrated drilling facility. It includes drilling and completion for more than 30 developments wells from the 40-slots.
The second phase is to develop the Lobito and Tomboco fields, which will produce via subsea wells tied into the central production hub. It will see a combined peak production of 200,000b/d by 2008.
Daewoo was awarded an $820m contract from Mustang, for engineering, procurement, construction and installation of the project’s production facilities, CPT, and the oil and gas export pipelines.
The topside modules were built at the yard Daewoo’s Okpo in South Korea. The topside section has an operating weight of 43,500t. Delta Engineering fabricated the 157-man accommodation module at its yard in Channelview, Texas.
Meanwhile, Sonamet constructed the drilling template, piles, flare boom, and helideck all weighing over 1,600t, at its yard in Lobito, Angola. Included in the topsides equipment are the facilities to handle 420,000b/d of water re-injection.
JACKET CONSTRUCTION
Fabrication of the tower portion of the production facility was split into two sections.
The tower base section and template, weighing over 26,000t was built by Kiewit Offshore. Technip’s Gulf Marine Fabricators constructed the tower’s 8,000t top section, The CPT’s bottom section consisted of 12 foundation piles, weighing around 11,000t, These were also fabricated in Ingleside, Texas.
SUBSEA CONTRACTS
The subsea part of the project went to Subsea 7 and Vetco Gray.
Subsea 7 won the $270m contract for the 10km tieback of three subsea drill centres to the CPT. The work included fabrication and installation of the steel pipelines, flowline jumpers, connectors and umbilicals, as well as installation of the subsea manifolds.
The steel flowlines were fabricated at the spoolbase in Luanda and the installation work was assigned to the pipelay vessel Skandi Navica.
Vetco Gray carried out the three-year, $125m contract for of 22 horizontal subsea trees, six manifolds, and the fully integrated subsea and surface control systems. The 80t subsea manifolds (three production and three water injection) were built at Lobito, Angola, for Vetco.
THE DRILLING RIG
The $120m engineering, procurement and construction operations and maintenance of the platform drilling rig was won by KCA/Deutag and National Oilwell Varco.
CPT’s integrated platform is capable of drilling to 30,000ft. It uses AC variable frequency drives. It is fitted with a mechanical pipehandling system installed in its hook-load derrick. This is equipped with 4,600hp drawworks and a top drive with 60,000lbft torque.
The rig also has three 2,200hp mud pumps rated to 7,500psi with a total mud volume of 4,625bbl.
The CPT’s topside modules were lifted by Heerema’s semi-submerisble crane vessel Thialf over a five-week period. When the 10,470t north module was installed, it represented Heerema’s largest installation using the Thialf’s anchorless dynamic positioning system. The vessel’s dual crane capacity provides for tandem lifts of up to 14,200t.
