Woodside Petroleum Ltd. plans to drill as many as 64 wells in pursuit to developing the Browse Basin gas fields offshore Western Australia.
Details of the planned development have emerged in the Browse Floating LNG (FLNG) Development Environment Protection and Biodiversity Conservation Referral document submitted to the federal government.
The Browse project, which includes Torosa, Brecknock, and Calliance gas-condensate fields about 290 km off Kimberley, will incorporate five drill centers at the Torosa reservoir and three each at Brecknock and Calliance.
Subsea infrastructure will include 12 manifolds, flowlines, umbilicals, and moorings.
The project also will employ three FLNG facilities, one of which may be moved between the Torosa and Brecknock-Calliance reservoirs.
Overall contingent reserves for the development are 16 tcf of dry gas and 436 million bbl of condensate.
It is likely there will be two facilities at Brecknock-Calliance for about half the fields’ life and two facilities at Torosa for half that field’s life.
The project is expected to have an operational lifetime of 50 years.
The use of FLNG technology will limit the project’s footprint to 67 ha.
The major challenge in an already complex plan is that much of the Torosa reservoir lies beneath Scott Reef. The reservoir also is compartmentalized and will require drilling from a number of locations to enable optimum recovery.
Production wells will be drilled to depths of 3,500-4,500 m below sea level. Some horizontal drilling will be needed.
Infield flow lines are likely to be flexible type or carbon steel internally lined with corrosion-resistant alloy.
FLNG design is expected to be similar to Royal Dutch Shell PLC’s Prelude project with each of the three vessels producing about 4 million tonnes/year of LNG along with as much as 22,000 b/d of condensate.
The FLNG facilities will each have eight storage tanks with capacities of 266,000 cu m. Boil-off gases generated during LNG storage and off-loading will be compressed for reuse in the fuel gas systems.
The vessels will be permanently moored to the seabed through turret mooring systems enabling the facilities to remain facing into the prevailing wind.
Mooring lines will be secured to the seabed by suction or attached to driven or gravity-based piles, each of which will be 6-8 m diameter and 30 long weighing 180 tonnes.
The project is expected to go into front-end engineering and design stage in 2014 with a final investment decision made in 2015.