CNOOC Ltd. has discovered and tested a high-yield natural gas well in ultra-deep volcanic reservoirs in the central Bohai area offshore China, opening a new exploration play in the Bohai basin, the company said in a Nov. 12 release.

The well, drilled adjacent to the hydrocarbon-rich Bozhong Sag, encountered more than 120 m of cumulative gas pay in volcanic formations and was completed at a depth of 5,770 m. It tested at about 800,000 cu m/day of natural gas.

CNOOC said the discovery marks a breakthrough in offshore ultra-deep volcanic gas exploration in Bohai, where complex geology and deeply buried reservoirs have challenged exploration efforts.

"The success of this well has opened up a new play for offshore ultra-deep natural gas exploration and expanded the scope of deep oil and gas exploration in Bohai," said Xu Changgui, chief scientist and chief geologist of CNOOC.

According to the company, the discovery could accelerate ultra-deep exploration activity in the Bozhong Sag and support development of Bohai Basin gas resources.