China National Offshore Oil Corp will pay A$50 million (US$49 million) for a 50-percent interest in Exoma Energy Ltd's coal seam gas blocks in Australia.

"This project is CNOOC's first relatively large-scale exploration of overseas onshore unconventional gas. If the exploration is successful, it will give CNOOC access to substantial natural gas resources overseas and provide a guarantee for stable liquefied natural gas supply," Fu Chengyu, president of CNOOC, said in a statement yesterday.

Under the agreement, signed in Beijing on Wednesday, CNOOC will gain access to five exploration blocks in Galilee Basin in Queensland. CNOOC also has an option to purchase a 19.9 percent stake in Exoma, the Australian firm said.

The Galilee blocks may contain more than 100 trillion cubic feet of gas resources, according to Exoma.

Unconventional gas, including shale gas, is expected to account for more than a quarter of China's gas supplies by 2030, and become a long-term solution to China's energy demand needs, according to Wood Mackenzie, a consultant.

Two months ago CNOOC's Hong Kong-listed unit, CNOOC Ltd, committed to spend US$2.2 billion over the next two years in Chesapeake Energy Corp's shale oil and gas deposits in the United States.