Oil and natural gas output at PetroChina's Changqing field has exceeded 20 million tons so far this year, meeting the company's 2007 target a few days early.

Changqing has become China's third largest oil field, after Daqing and Shengli.

A PetroChina official said Changqing took 33 years to reach an annual oil and gas output of 10 million tons but only four years to double that level. The official said this progress was almost miraculous in light of the history of ultra-low-permeability oil field development.

During the past 30 years, its aggregate output of crude oil grew 1.35 times to reach 57.02 million tons. On the natural gas front, its output rose 17-fold over the past 30 years to 42.75 billion cubic meters.

In an attempt to cut costs, the oilfield reduced the number of large-scale production facilities, usually with a capacity of more than one million tons, from 25 to five that used more efficient technology. It had thus been able to employ fewer people -- one third fewer than other oilfields with equivalent capacities.

PetroChina Changqing Oilfield, located in the Ordos Basin, is one of the most important oil and gas blocks in China. Its oil and gas are marketed in several western provincial regions including Shaanxi, Gansu, Ningxia, Sichuan and Inner Mongolia.