CNOOC Limited announced 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 meters per day of absolute open flow natural gas, marking the first major exploration breakthrough 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 kilometers southeast of Shenzhen with a water depth of nearly 1,640 meters. The well was drilled to a vertical depth of nearly 3,000 meters, completed at a depth of nearly 4,400 meters, and encountered gas pay zone of approximately 650 meters in the horizontal section.

 The well has revealed promising exploration prospects in the ultra-deepwater Globigerinid limestone in China, and effectively promotes the natural gas exploration process in Baiyun Sag.

"Previously, exploration in China's ultra-deepwater areas mainly focused on clastic rocks. 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.

In addition, this discovery is close to the existing production facilities of Liwan3-1 gas field, which could be utilized to develop the new discovery, thereby, enabling economic and efficient development of natural gas resources in the deep waters of the Pearl River Mouth Basin," Xu Changgui, Chief Geologist of the company, said.