After a decade-long search for oil from central Asian deserts to the floors of the Pacific, PetroChina has found an offshore field in Bohai Bay that could become China’s biggest new domestic petroleum source for years, with reserves of 2.2 billion barrels.

The scale of the find, if confirmed, would be welcome news to the government, eager to find oil to fuel is burgeoning economy.

Such a field would be a “world-scale discovery,” said Gavin Thompson, an oil consultant in Beijing for the Scottish firm Wood Mackenzie. “In terms of energy security, a two-billion-barrel discovery is going to be very welcome, not only to PetroChina but to China’s energy planners,” he said.