Workers yesterday completed a tunnel under the Yangtze River for a major gas pipeline that will run from southwest Sichuan Province to Shanghai.

Industry experts said the new pipeline, with an investment of 62.7 billion yuan (US$8.25 billion), also offers an opportunity for China's underdeveloped west to tap into its natural resources.

With a diameter of 3.08 meters and a length of 1,405 meters, the tunnel which sits about 20 meters beneath the riverbed, connects two wells on each bank of the Yangtze in Yichang City of Hubei Province, said Liu Juzheng, head of the Hubei section of the Sichuan-Shanghai pipeline.

The 2,203-kilometer pipeline, with the main line extending 1,700km, is another energy artery to fuel the booming but energy-insufficient eastern areas following the first west-east gas project.

The pipe is expected to channel 12 billion cubic meters of natural gas annually from Sichuan's Puguang field to central and eastern regions, including Chongqing Municipality, the provinces of Hubei, Anhui, Jiangxi, Jiangsu and Zhejiang, and Shanghai.

The tunnel, which took 325 days to finish, is the first of five that will cross under the Yangtze, which originates in Qinghai Province and empties into the East China Sea near Shanghai. The remaining four tunnels of the new gas pipeline will cross under the Yangtze at Zhongxian County of Chongqing, Wuhan and Huangshi in Hubei Province, and Anqing in Anhui Province.

Workers have so far laid 500km of the pipeline project.

The pipeline is scheduled to be completed by late 2010 and the gas is expected to help reduce carbon-dioxide emissions by tens of millions of tons annually, said Chen Deming, vice minister of the National Development and Reform Commission.

Proven reserves of the Puguang gas field stand at 356.1 billion cubic meters, according to the China Petrochemical Corporation (Sinopec).

Puguang field will be capable of producing 12 billion cubic meters of purified gas by 2010, equivalent to 10 million tons of standard coal annually. China's proven reserves of natural gas total 2.66 trillion cubic meters.

The government has been promoting the use of natural gas to improve energy efficiency and cut air pollution.

Under an NDRC proposal on natural-gas development, China aims to increase its pipeline network to 44,000km by 2010.

Although China's natural-gas output will reach 94 billion cubic meters in 2010 from 58.6 billion in 2006, the country will still need imports to fill a gap of 16 billion cubic meters yearly.

In Shanghai, demand for natural gas soared from four million cubic meters in 2003 to 1.9 billion cubic meters in 2005.

In 2004, the China National Petroleum Corp launched its west-east pipeline, which runs more than 4,000km and channels 1.2 billion cubic meters of gas annually to Shanghai from the Tarim Basin in the western Xinjiang Uygur Autonomous Region.

CNPC will build a second west-east pipeline to carry gas imported from Central Asia to the Pearl River and Yangtze River deltas. Construction will begin in 2008 and it will be operational in 2010. Annual transmission capacity will be 30 billion cubic meters.