China's top two oil and gas companies have accelerated shale gas exploration.

PetroChina Co, China's largest oil and gas producer, announced on Friday that its first shale gas project in Daqing, Heilongjiang province, started test runs in early October.

Sinopec Co, the country's largest refiner, said it has discovered enough shale gas resources for commercial scale production in Chongqing on Oct 28.

The company said its shale gas block in Chongqing has reached the maximum daily output of 547,000 cubic meters.

Insiders said the top two oil and gas companies – PetroChina Co and Sinopec Co – have accelerated their shale gas exploration since the government included the shale gas industry into the strategic emerging industries.

According to China's 12th Five-Year Plan (2011-2015) for shale gas development, the country's total shale gas output will reach 6.5 billion cubic meters in 2015, which will lead to an investment of 400 billion yuan ($66 billion) in the sector.

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