New ultra-deepwater gas discovery reported off China

China National Offshore Oil Corporation (CNOOC) has confirmed that it has drilled a natural gas well in the ultra-deepwater Liwan 4-1 structure in the Pearl River Mouth Basin.

The well was tested to produce 430,000 cubic metres of absolute open flow natural gas per day, making it what CNOOC said is the first major exploration discovery in ultra-deepwater carbonate rocks offshore China.

The well is located in Baiyun Sag, the largest hydrocarbon-rich sag in the Pearl River Mouth Basin, about 300 kilometres southeast of Shenzhen with a water depth of nearly 1,640 metres. The well was drilled to a vertical depth of nearly 3,000 metres, completed at a depth of nearly 4,400 metres, and encountered gas pay zone of approximately 650 metres in the horizontal section.

CNOOC said the well has revealed promising exploration prospects in the ultra-deepwater Globigerinid limestone in China, in addition to promoting natural gas exploration in Baiyun Sag.

"Previously, exploration in China's ultra-deepwater areas mainly focused on clastic rocks," said Xu Changgui, Chief Geologist of CNOOC. "The success of this well has, for the first time, revealed the enormous potential of carbonate rocks in China's ultra-deep waters, marking significant breakthroughs in both exploration understanding and operational techniques."