XI'AN -- China's largest oil-and-gas field, Changqing oilfield, had produced over 17.7 billion cubic meters of natural gas during this winter heating season, statistics as of March 15 showed.

As China's largest natural gas production base, the oilfield supplies natural gas to more than 40 major cities, including Beijing and Tianjin. For four consecutive years, its daily gas output during winter peak supply has maintained an increase of 10 million cubic meters.

During the latest heating season, Changqing oilfield also offered sufficient natural gas supplies to the Olympic Villages in the three competition areas of the Beijing Winter Olympics and relevant hotels.

Over the past 25 years, Changqing oilfield has supplied more than 520 billion cubic meters of natural gas, equivalent to the total calorific value of power generated by the Three Gorges Hydroelectric Power Station on China's Yangtze River in 40 years.