Project Profile
Value: US$1.2 billion (only for the fields development)
Location: 160 miles (257 kilometres) east of Corpus Christi, Texas, USA
Reserves: 300 million barrels of oil equivalent
Production: 80,000 bopd and 200 MMcf/d (5.7 MMcm/d)
Water Depth: 1,463 metres
Length (pipelines): 137 kilometre and 241 kilometres pipelines
Discovery: 1997 (Hoover field), 1990 (Diana field)
The Hoover-Diana field is a deepwater GOM oil and gas development located 257 kilometres east of Corpus Christi, Texas. ExxonMobil, operator, has a 66.7% vested interest and BP Amoco holds the remaining 33.3% interest. The Hoover field, about 24 kilometres east of the Diana field, was discovered in 1997 on Alaminos Canyon Blocks 25 and 26. Discovered in 1990, Diana is located on East Breaks Blocks 945, 946, 988, and 989. The fields, in 1,463 metres of water, have estimated combined recoverable reserves of 300 million barrels of oil equivalent. Through an integrated development initiative, both fields came on-stream with development costs estimated at US$1.2 billion. Commencing production in 2000, Hoover-Diana\'s current production averages more than 80,000 bopd and 200 MMcf/d (5.7 MMcm/d). The Hoover-Diana project received OTC\'s Distinguished Achievement Award for Companies, Organisations and Institutions in 2002. The DDCV also ties satellite fields Madison and Marshall to its facility and were developed by three-well remote subsea developments. Both fields are situated about 11 kilometres from the vessel.
Field Development
The integrated field development included wells on both fields connected to a Deep Draft Caisson Vessel platform (DDCV), located in 1,463 metres of water on the Hoover field. An industry first, the DDCV set the record for water depth and associated subsea development. The semisubmersible Marine 700 was contracted from Marine Drilling to drill the Diana and Hoover wells. In The six Diana wells were connected through a subsea manifold and flowlines to the DDCV platform 15 miles (24 kilometres) away. With subsea trees on each well, hydrocarbons are transferred from the Hoover wells to the DDCV via vertical risers.
DDCV
The DDCV platform, with drilling and production facilities, is located on the Hoover field at Alaminos Canyon Block 25. In 1999, it was towed to its offshore location, then up righted and production decks were installed. Aker Rauma Offshore was awarded the DDCV construction. With a catenary-moored steel cylindrical hull, the 62,000-ton vertically floating vessel is 46 metres in diameter and 311 metres tall. The buoyed vessel has air-filled compartments in the upper portion of the hull and is ballasted with seawater in the bottom compartments. A 15,422 tonne hull section of the DDCV was fabricated at the Aker Gulf Marine fabrication yard in Corpus Christi, Texas. The second hull section was completed at Aker Mantyluoto in Pori, Finland. The two sections were combined at the US fabrication yard prior to its launch in the GOM. A three-level deck houses separation, dehydration and treatment facilities for 100,000 bopd, 325 MMcf/d (9.20 MMcm/d), and up to 60,000 barrels of water per day, as well as a drilling rig. The platform\'s topsides were designed by Mustang Engineering and fabricated by Brown and Root Energy. Twelve 2,164 metre-long anchor lines moor the vessel to the seafloor; each line consists of a chain and a spiral-strand wire rope. At the time, the 32 metre-long, 249 tonnes mooring piles were the largest ever installed on an oil and gas platform. Saipem using the Saipem S-7000 vessel installed the topsides, suction pilings, mooring lines, flowlines, steel catenary risers and export lines.
Pipelines
The DDCV does not have storage capabilities to store produced hydrocarbons, instead it pumps oil and gas onshore through pipelines. An 137 kilometre gas pipeline was constructed from the DDCV to the High Island Offshore System, which is an existing gas transmission system off the Louisiana coast. Also, an oil pipeline was built, which extends 241 kilometres to Freeport, Texas. These two pipelines were one of the longest in the GOM.
Operators:
ExxonMobil: Operator with 66.7% interest
BP Amoco: 33.3% interest
Contracts:
Aker Rauma Offshore: Main EPC contract for the DDCV construction
Brown and Root Energy: Fabrication of the platform\'s topsides
Marine Drilling: Drilling contract for the Diana and Hoover wells
Mustang Engineering: Design of the platform\'s topsides
Saipem: Install the topsides, suction pilings, mooring lines, flowlines, steel catenary risers and export lines