In 1995, the Bayu-Undan field was discovered in the Timor Sea, approximately 150 miles south of Suai, Timor-Leste, and about 300 miles north-west of Darwin, Australia. Additional appraisal drilling over the next two years confirmed that the field has estimated recoverable hydrocarbons of 4 trillion cubic feet of gas and 550 million barrels of condensate and liquefied petroleum gas.
The Darwin LNG plant converts the gas from the Bayu-Undan field into LNG for sale to Tokyo Electric and Tokyo Gas in Japan. Construction of the Darwin LNG plant and manufacture of the line pipe began in 2003. LNG deliveries to Japan commenced in early 2006 pursuant to a Sales and Purchase Agreement for a term of 17 years.
The equity ownership of the Bayu-Undan facility, the pipeline and the Darwin LNG plant is held by various companies. ConocoPhillips is the operator of the project.
Bayu-Undan Offshore Project
The Bayu-Undan surface facilities consist of three primary components:
- A central production and processing complex
- An unmanned wellhead platform
- A floating storage & offloading facility (FSO)
The central production and processing complex comprises two separate bridge-linked platforms: the drilling, production and processing (DPP) platform and the compression, utilities and quarters (CUQ) platform. The combined topsides facilities weigh close to 26,000 metric tons, and each platform sits on top of a 10,000 metric tonne eight-pile steel jacket in water 260 feet deep.
Both jackets are built from high strength steel to withstand extreme cyclones and earthquakes as well as collisions with boats.
The DPP platform provides approximately two thirds of the 1.1 billion standard cubic feet per day of raw liquid rich gas from the reservoir via four production wells. It also provides the processing facilities to separate the well fluids into gas and liquid products.
The CUQ platform provides the compression facilities for the processed gas to be either reinjected back into the Bayu-Undan reservoir or exported to shore via a subsea pipeline. It also contains living quarters for eighty people and a helideck.
The unmanned wellhead platform is located 4.6 miles to the west of the central production and processing platform and is comprised of 1,500 metric tons of topsides. It serves as a secondary production center for the field, normally supplying approximately one third of the planned 1.1 billion standard cubic feet per day of raw liquid rich gas to the DPP platform via a subsea pipeline.
The FSO is the world’s first multi-product condensate and LPG storage facility. It is equipped with refrigeration, liquefaction and gasification facilities and can store 130,000 cubic meters of condensate and 95,000 cubic meters combined of propane and butane. The FSO is permanently positioned 1.4 miles north of the Central Production and Processing complex and is linked to the DPP by four subsea pipelines carrying condensate, butane and propane as well as fuel gas for power generation.
Bayu-Undan to Darwin Pipeline
A 300 mile, 26-inch subsea pipeline connects the Bayu-Undan facility, located in the Timor Sea, to the Darwin LNG plant in Darwin, Australia. The pipe laying commenced in Darwin Harbour in August 2004 and was completed in January 2005.
The entire steel order was 160,000 tonnes. Each pipe joint is approximately 40 feet in length and has an associated weight of approximately 7-14 tonnes each.
Darwin Liquefied Natural Gas Plant
Construction of the Darwin Liquefied Natural Gas (LNG) plant commenced in June 2003 and the plant was commissioned in the first quarter 2006 when LNG sales started.
The Darwin LNG plant uses the ConocoPhillips Optimised (SM) Process as the basis for its LNG liquefaction technology. This technology employs a two-trains-in-one design for increasing reliability and flexibility. It was first used in 1969 in ConocoPhillips’ Kenai LNG plant in Alaska. The Darwin LNG plant continues to build on this history of innovation by being the first LNG plant to use high efficiency, low emission, aero-derivative gas turbines as refrigerant drivers.
The Darwin LNG plant also incorporates several other design features to reduce greenhouse gas emissions. One such feature is the waste heat recovery on the gas turbine exhaust that is used for various heating requirements within the plant. Additional equipment has been installed to recover vapours generated from the LNG ships during LNG loading, ensuring emissions are minimized.
The Darwin LNG plant minimizes nitrogen oxide emissions from the gas turbines by the injection of water into the gas turbines.
ConocoPhillips Optimized Cascade Process
The ConocoPhillips Optimised Cascade (SM) Process progressively cools the gas through refrigeration phases down to minus 161 degrees Celsius. At this temperature, the natural gas becomes a liquid that takes up 600 times less volume, enabling it to be safety and efficiently shipped to customers in specially designed LNG tankers
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