FACTBOX: Australia's Gorgon, gas source for China

PERTH (Reuters) - Australia and China struck their biggest trade deal ever on Tuesday, as the world's top two most valuable listed oil companies, ExxonMobil (XOM.N) and PetroChina (601857.SS) inked a $41 billion liquefied natural gas (LNG) deal.

Under the agreement, PetroChina will buy 2.25 million tonnes per annum (mtpa) of gas from Exxon's share of gas from the proposed Gorgon LNG project for a period of 20 years.

The massive Gorgon project off western Australia, which has a proposed capacity of 15 mtpa, is operated by Chevron Corp CXV.N with a 50 percent stake. Royal Dutch Shell (RDSa.L) and Exxon each own hold 25 percent.

Following are some facts about the Gorgon project:

* The Gorgon project plans to develop the Greater Gorgon gas fields, located between 130 km and 200 km off the north-west coast of Western Australia. The gas fields contain resources of about 40 trillion cubic feet of gas, Australia's largest-known gas resource.

* The project, which the government has estimated to cost A$50 billion, will be the largest resource project built in Australia, eclipsing the A$25 billion North West Shelf LNG project operated by Woodside Petroleum Ltd (WPL.AX). It will also boost the government's gross domestic product by A$65 billion and add around 6,000 jobs.

* Venture partners for the project are marketing their share of the gas separately. Chevron has entered an agreement for the sale of Gorgon LNG with Tokyo Gas (9531.T), Chubu Electric (9502.T) and Osaka Gas (9532.T) for between 1.2-1.5 mtpa over 25 years, as well as 0.25 mtpa to GS Caltex.

* Shell, which plans to sell some Gorgon LNG into North America, will supply 1 mtpa of Gorgon LNG to PetroChina and has also signed a memorandum of understanding with Gujarat State Petroleum Corporation Ltd in India for the possible sale of 0.5 mtpa of LNG.

* Apart from the latest deal with PetroChina, Exxon has also inked a supply deal with India's Petronet (PLNG.BO) to sell 1.5 mtpa of LNG from the Gorgon project over 20 years, which is worth about A$1 billion.

* Australia's government moved a step closer to approving the Gorgon project on Monday, after agreeing with the state government to assume joint responsibility for any future claims arising from plans to capture and store the venture's greenhouse-gas emissions deep underground.

* Venture partners for Gorgon say they are targeting a final investment decision for the project before the end of this year.

(Reporting by Fayen Wong, editing by William Hardy)