XI'AN,Shaanxi - The total crude and gas output of Changqing Oilfield in northwest China exceeded 40 million tons of oil equivalent (TOE) by Tuesday, ranking it the country's second largest oilfield, the company said.

Changqing was after Daqing Oilfield, the annual output of which had already broken the 40-million-tonmark this year, the subsidiary of China's largest oil and gas producer PetroChina said in a press release.

The whole-year output in 2011 is expected to hit 40.6 million tons of oil equivalent, the statement said, adding that natural gas accounted for about half of the output.

Changqing's output in 2010 was 35 million tons of oil equivalent, with 18.3 million tons of crude oil and 21.1 billion cubic meters of natural gas.

Changqing Oilfield has seen proven oil and gas reserves increase by an average of 200 million tons and 200 billion cubic meters, respectively, in each of the past four years.

Meanwhile, its output has grown by an average of 5 million tons for four consecutive years, representing the fastest growth nationwide.

Changqing Oilfield added that its output of oil equivalent is expected to rise to 50 million tons in 2013.