China 's domestic natural gas output is expected to reach 176 billion cubic meters by 2015, compared with 102.5 billion cum in 2011, the National Energy Administration said Monday.

Total production will include 138.5 billion cum of conventional natural gas, 15-18 billion cum from coal and about 16 billion cum from coal bed methane, the administration said in a statement on its website.

By 2015, consumption is expected to reach 230 billion cum, with overseas supplies accounting for more than 35% of total demand, up from 15% in 2010, the statement said.

"This will bring new challenges to
China 's energy safety and China must strive to increase effective domestic supplies while at the same time optimizing the consumption structure," it said.

China 's annual imports of natural gas are expected to reach around 93.5 billion cum by 2015, the administration said, compared with 17 billion cum in 2010.

The administration also said
South China Sea will be the nation's main offshore natural gas producing base, and it aims to produce 15 billion cum of natural gas annually by 2015. It didn't specify how much natural gas was produced in South China Sea area last year.