Bayu-Undan, Timor Sea, Australia

Bayu-Undan lies in the Timor Sea, 500km offshore of Darwin and 250km south of East Timor. It straddles the boundary between blocks 91-12 (60%) and 91-13 (40%), within Area A of the Australia/Indonesia Zone of Cooperation. The fields are located on the same 160km² structure, in 80m of water.

The operator is ConocoPhilips, which has a 56.27% stake, its partners being Eni (12.04%), Santos (10.64%), Inpex (10.53%) and Tokyo Electric Power and Tokyo Gas (10.08% each).

Discovery

Bayu was discovered in early 1995, when the Bayu-1 well intersected a 155m gas/condensate column, at a depth of 897m. This tested 2.54m³/day of gas and 5,250bbl of condensate. The follow-up well, Bayu-2, tested 991,000m³/day of gas and 2,000bbl of condensate from a 52m interval.

In July 1995, Undan was discovered 10km north-west of Bayu, where a 139m gross hydrocarbon column tested 1.6 million m³/day of gas and 3,900bbl condensate/day. The total recoverable field of reserves is 350-400 million barrels of hydrocarbon liquids and 3.4TCF of gas.

The 25x15km field will require approximately 26 wells over its lifetime to produce the reserves, 16 of which - including the first high-angle well in the Timor Sea - will be required before start-up. The field life is estimated to be 25 years. Commercial production began in April 2004, delivering 115,000 barrels per day of condensates and LPG.

The project has been developed in two phases. The US$1.8b n first-stage gas-liquids phase involved the production and processing of wet gas, the separation and storage of condensate, propane and butane, and the re-injection of dry natural gas back into the reservoir. This phase also involved the construction of a remote Wellhead platform, a Drilling, Production and Processing platform and a Compression, Utilities and Quarters platform. The recovered liquids are piped to a Floating Storage and Offloading (FSO) facility.

Total Integrated Group Approach (TIGA), an alliance between Fluor Daniel and Worley, was selected as the engineering and procurement contractor.

The development complex includes:

Wellhead (WH) platform

This unmanned structure was installed in April 2006 and consists of 17.7x24.4m topsides, supported by a four-leg 1,319t jacket.

The compression, utilities& quarters (CUQ) platform and the drilling, production & processing (DPP) platform

These both consist of an 8-leg steel jacket, slotted to accommodate topside deck floatover. The jacket dimensions are 48x50m, with a height of 90m. The topsides were built at the Hyundai fabrication yard in Ulsan, South Korea. The CUQ topsides weigh 11,500t and are 72m long, 80m wide and 31m high, while the DPP topsides weigh 13,900t and are 65m long, 64m wide and 41m high.

The processing equipment includes three 23MW gas-turbine-driven injection compressors, two 7.5MW gas-turbine flash gas compressors and two turbo expanders. It has high-pressure (100/310bar) column vessels and four gas-turbine-driven generators. The topsides were installed in November 2003 by Dockwise, under a contract awared to it by Perth-based Clough-Aker Joint Venture covering their transportation and installation.

Floating storage and offloading facility (FSO)

This integrated condensate and LPG storage offloading facility – the world’s first at the time – can store 820,000bbl (130,000m³) of condensate, 300,000bbl (47,500m³) of Propane and 300,000bbl (47,500m³) of Butane. It has no propulsion system of its own and is 248m long, 54m wide, with a tonnage of 150,000dwt. Accommodation is available for 60 people.

The purpose-built FSO, named the Liberdade, was built by Samsung Heavy Industries, launched in Korea in September 2002 and permanently positioned offshore in the field about a year later. It processes the condensate and LPG, and stores them before they are loaded onto tankers for export. As such, it is designed to exploit remote oil and gas reserves that might otherwise be stranded for decades.

Pipelines

Flowlines between the WHP and DPP will consist of an 8km,18in carbon steel CRA-lined production line and an 8km,16in injection line.

Flowlines between the DPP and FSO will consist of a 12in condensate line, a 6in carbon steel propane line, a 6in butane line and a 4in carbon-steel fuel gas line, all 2.3km long.

Phase 2

The second phase of development, the gas phase, began production in February 2006, and cost $1.5bn. This involves the extraction of lean gas from the reservoir and transportation to Darwin, on Australia’s northern coast, via a 26in, 500km pipeline, where it is liquefied at a single-train processing plant at Wickham Point then shipped as LNG to customers Tokyo Electric Power Company and Tokyo Gas in Japan.

It has a production capacity of 3.24m tons per annum, and ConocoPhillips has entered into agreements with the two companies to supply 3m tons of Bayu-Undan LNG per year over 17 years.

The plant was built under a Lump Sum Turn-Key contract with units of the Bechtel Corporation, which subcontracted the construction of the LNG storage tank to a consortium of Theiss, of Australia, and TKK, of Japan.