CNOOC makes breakthrough in ultra-deepwater exploration

CNOOC 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 cu m 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 km southeast of Shenzhen with a water depth of nearly 1,640 m. The well was drilled to a vertical depth of nearly 3,000 m, completed at a depth of nearly 4,400 m, and encountered gas pay zone of approximately 650 m 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.

Xu Changgui, Chief Geologist of the company, said, “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.”