Green Canyon, US Gulf of Mexico
Caesar Tonga is an oil field located approximately 300km from New Orleans in Louisiana, USA. It is situated at a water depth of about 1,500m in blocks 683, 726, 727 and 770 of the Green Canyon area of the US Gulf of Mexico (GoM).
Anadarko Petroleum is the operator of the Caesar Tonga joint development and has a working interest of 33.75% in the development.
Statoil Gulf of Mexico, a subsidiary of Statoil, Shell Offshore, a subsidiary of Royal Dutch Shell, and Chevron USA are the co-owners of the project with working interests of 23.55%, 22.45% and 20.25% respectively.
High quality oil production from the field began in March 2012. The first oil was originally scheduled for mid-2011, but was delayed due to a mechanical fault in the production riser system.
Caesar Tonga field is estimated to hold a resource base of 200 to 400 million barrels of oil equivalent (BOE). Production from the first three production wells is expected to ramp up to about 45,000 BOE a day.
Caesar Tonga will be developed as a sub-sea tieback to the Anadarko-operated floating production platform, Constitution. The development works began in early 2007 under a combined single development that comprises Tonga, Tonga West and Caesar fields.
The first phase of development of Caesar Tonga is estimated to cost $1.3bn and includes construction of four wells. The first three wells were put into operation in March 2012. The fourth development well is anticipated to be completed before the end of 2012.
Flow and reservoir tests on the first three development wells were undertaken during the second quarter of 2011. The wells tested flow rates of about 15,000 barrels of oil each day (BOPD) of high quality oil.
The topside facilities of the Constitution spar platform were commissioned in the first quarter of 2012. The offshore pipeline from Caesar Tonga was attached to the spar using lazy-wave steel catenary riser (SCR) technology, which is first of its kind to be used in the Gulf of Mexico.
The Constitution spar is located in Block 680 of Green Canyon in about 1,524m of water. It had a design capacity of 70,000 barrels of oil a day and 200 million cubic feet of natural gas a day at the time of launch in 2006.
The topsides of the platform were modified in order to accommodate the Caesar Tonga tieback. The modification work was started in the fourth quarter of 2009 and completed in the first quarter of 2012.
Manufactured by Technip at its Pori yard in Finland, the spar now facilitates oil production from the Caesar Tonga field in addition to the Ticonderoga and Constitution fields.
In July 2009, Anadarko awarded two lump sum contracts to Technip.
The first contract involved design and supply of components for four pipe-in-pipe flowlines and installation of flowlines measuring 43km in length. Technip was also required to design, assemble and install eight pipeline end terminations (PLETs). The offshore installation was done using Technip’s deepwater pipelay vessel Deep Blue.
The second contract was awarded to Technip’s wholly owned subsidiary Duco. The scope of the contract included project management, engineering and assembly of two control umbilicals with terminal equipment.
Subsea 7 was awarded an engineering, construction and installation contract in November 2009 for the development of the Caesar Tonga complex. Insulation work for the sub-sea tieback was undertaken by Aspen Aerogels.
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