Under the terms of the farm-in, China's largest offshore oil and gas producer will acquire a 50% interest in ATP 991, 996, 999, 1005 and 1008 in the central Queensland Galilee Basin by contributing $50 million towards exploration and appraisal expenditure.

CNOOC also has an option to acquire 86.6 million ordinary shares in Exoma at 31.5c per share, representing a $27 million investment in the company. Each share will be issued with one free attaching option to acquire further shares at 31.5c.

Exoma's permits cover 26,840 square kilometres and are prospective for both coal seam gas and shale gas with an estimated gas-in-place resource of more than 100 trillion cubic feet.

CNOOC says it has the desire to acquire an interest in a significant gas exploration area in Queensland which it believes has the potential to support one of the largest CSG and shale gas projects in Australia.

Exoma chairman Brian Barker said it was a positive endorsement that CNOOC shared the company's technical and commercial assessment of the resource potential of the Galilee permits.

"With CNOOC's involvement, Exoma will now accelerate its exploration program for its Galilee Basin permits, which Exoma believes host very large coal seam gas and shale gas resources, with additional potential for conventional petroleum resources," he said.

"We are confident that these gas resources will underpin one or more large downstream gas development projects serving both export and domestic gas markets for many years."

Earlier this year, CNOOC became a joint venture partner and major customer for BG Group's Queensland Curtis liquefied natural gas project.

In addition, the company has recently received Foreign Investment Review Board approval to acquire a controlling interest in Altona Energy's Arckaringa coal-to-liquids project in South Australia.

The Exoma deal is subject to Australian and Chinese government approvals.

Exoma, which was in a trading halt yesterday, opened at 31c this morning, up from Tuesday's closing price of 29c.