Typhoon, Gulf of Mexico, USA

The Typhoon oil field is located in blocks 236 and 237, in the central Green Canyon area of the Gulf of Mexico. This lies approximately 100 miles off the coast of Louisiana, in water depths of 2,000ft. The field is being developed jointly by the operators Chevron and BHP, with each owning a 50% equity interest.

First production is scheduled to take place less than 3.5 years after the first discovery. Typhoon has an estimated field life of around six to eight years.

The Typhoon field is a combination structural-stratigraphic trap, with four separate fault blocks. Subsequent to the discovery well in 1998, four appraisal wells were drilled. The late Pliocene stacked deepwater turbidite sands exhibit excellent reservoir properties and are expected to support high flow rates.

The quality of the oil at Typhoon has an average API gravity of 32° and is similar to the crude oil currently being produced at other Green Canyon fields.

The development plan for Typhoon is designed to deliver a peak production rate of 40,000 barrels of oil per day and 60 million standard ft³ of gas (gross).

SEASTAR PLATFORM

The development consists of the subsea completion and tieback of the four existing appraisal wells and the construction and installation of a local host facility, based on an Atlantia SeaStar mini-tension leg platform (TLP). The SeaStar TLP will be installed in the eastern half of the Green Canyon block 237 in 2,097ft of water. Two export pipelines for oil and gas will transport hydrocarbons to existing markets.

In February 2000, Atlantia Offshore Limited was awarded the Typhoon development from Chevron/BHP. The topsides will include production, utility and accommodation capability. Production facilities will separate, treat and measure oil, gas and water production, for 40,000b/d oil and 60 million ft³/day of gas. Dehydrated gas and treated crude will be transported via separate pipelines and treated, whereas any produced water will be treated and discharged on-site.

TOPSIDES STRUCTURAL DECK

The main topsides structure is based on two levels consisting of a 110ftx110ft main deck and a 110ftx110ft production deck. The other main structural units are a four-point hull support and a flare boom.

The processing facilities are based on a two-stage separation system (two-phase separation in the high pressure separator and three-phase separation in the low-pressure separator).

The gas processing system consists of a two-stage main gas compression system and a 5,000ft³/day two-stage vapour recovery compression system. There is also a 15,000b/d produced-water system, which is based on hydrocyclones in association with a downstream column flotation unit.

Other process systems include process heating and cooling systems, a well and production chemical-injection system and direct hydraulic control of the subsea wellheads.

The platform has an 8,500kW main generator (two units at 4,250kW each, dual fuel) and an 820kW emergency generator. There is also an instrument and utility air system, fuel gas system, fire-water system, fire and gas-detection systems and a flare system.

SEASTAR HULL

The SeaStar hull has a 58ft diameter and a column extension of 18ft. It has a 130ft (+/-3ft) main column length. It is secured to the anchoring system by four-point topsides support. The mooring system consists of six tendons, top connectors, bottom connectors, top transition joints, bottom transition joints and foundation piles.

The pipeline and flowlines/umbilicals consist of one 18in gas export riser, one 10in oil export riser, six well flowlines and six direct hydraulic cell-control umbilicals. There is also one 18in gas import riser.