CNOOC Ltd. announced Sept. 10 it has drilled a natural gas well in the ultra-deepwater area of ​​the Liwan 4-1 structure in the Pearl River Mouth Basin. The well marks the first major breakthrough in China’s ultra-deepwater carbonate exploration, as it yielded a daily unimpeded natural gas flow rate of 430,000 cu. m.

The well is located in the Baiyun Sag and sits 300 km southeast of Shenzhen in 1,640 m of water. Drilled to a vertical depth of nearly 3,000 m and completed at a 4,400 m, the well encountered a gas pay zone of approximately 650 m in the horizontal section.

In a press release, Xu Changgui, CNOOC’s chief geologist, said that existing production facilities at the nearby Liwan 3-1 gas field could be utilized to develop the new discovery.

"In the past, China's ultra-deepwater exploration was mainly based on clastic rocks,” Changgui said. “The successful drilling of this well revealed for the first time the huge potential of China's ultra-deepwater carbonate rocks, a new exploration field, and marked an important breakthrough in both exploration knowledge and operation technology in this field.”

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