Non-oil companies bid more aggressively than the oil companies in China's second shale gas auction, according to an official from the Ministry of Land and Resources (MLR).

The most vigorous bids came from investment, real estate, electricity and coal companies, said Zhang Dawei, head of the ministry's reserve appraisal center. "Looking from the award results, it's fair to say that non-oil and gas firms will be involved in shale gas business," he said.

"It certainly means more opportunities for the service guys like Schlumberger and Weatherford, as these non-oil companies don't have their own expertise," one U.S. energy executive told Reuters.

On Sept. 10, the MLR announced an offer of 20 shale gas blocks in a second tender, with a total area of 20,002 square km, allowing both private companies and foreign-funded joint ventures controlled by Chinese firms to participate. It was the first time for the Beijing government to offer this kind of approval for access to upstream rights in the oil and gas industry.

Eighty-three companies submitted a total of 152 bids, including six joint-venture bidders, and the results are expected to be released soon.

Earlier this year, China's resource ministry revealed that it had discovered 25.1 trillion cubic meters of untapped shale gas reserves, which could fuel the country's current natural gas needs for 200 years.

Although this is a lower figure than the 31 trillion cubic meters predicted by the U.S. Energy Information Administration, China, the world's top energy user, still has one of the largest shale gas reserves in the world.