China National Offshore Oil Corp (CNOOC) has started seismic operations at its first onshore shale gas project, the near monopoly in China's offshore oil and gas development said, joining other state majors to scour for unconventional energy.

CNOOC Ltd, which runs CNOOC's oil and gas businesses, will undertake the exploration and development work in the 4,800-square-kilmetre block in eastern Anhui province, CNOOC said.

China's onshore oil and gas exploration and production are dominated by PetroChina and Sinopec .

The world's largest energy consumer now treats shale gas as a resource independent from conventional hydrocarbons, which could facilitate the introduction of policies to bring in more firms to develop the potentially huge resource.

Although it has yet to start commercial shale gas production, China has set an ambitious target to pump 6.5 billion cubic metres by 2015 and 80 bcm by 2020, equivalent to around 80 percent of the country's estimated total gas output in 2011.