Another ‘major breakthrough’ for Asian giant as new oil & gas pay zone comes to light

July 16, 2025, by Melisa Cavcic

Chinese state-owned oil and gas giant China National Offshore Oil Corporation (CNOOC) has expanded its discovered oil and gas reserves with a new hydrocarbon find in the Beibu Gulf of the South China Sea.

Following the WZ10-5-1Sa exploration well, which encountered an oil and gas pay zone of 283 meters at the Weizhou 10-5 oil and gas field in the Beibu Gulf, CNOOC has confirmed the achievement of a new “major breakthrough” in the exploration of metamorphic buried hills in the deep plays of the South China Sea with the WZ10-5S-2d exploration well that hit an oil and gas pay zone of 211 meters, with a total drilled depth of 3,362 meters.

Zhou Xinhuai, CNOOC’s Chief Executive Officer, highlighted: “This represents the first major breakthrough in metamorphic sandstone and slate buried hills exploration offshore China, setting important example for advancing deep plays and buried hills oil and gas exploration.

“In the future, CNOOC Limited will continue to intensify research on key theories and technologies for deep play exploration, to enhance research and development capabilities, advance reserves and production growth, and to ensure stable supply of oil and gas.”

‘Major breakthrough’ in Chinese giant’s exploration ops with new oil & gas pay zone

Exploration & Production

According to the Chinese player, the test results indicate that the well produces 165,000 cubic feet of natural gas and 400 barrels of crude oil per day. As a result, the firm underlines that this marks “a major exploration breakthrough” in the metamorphic sandstone and slate buried hills offshore China. The Weizhou 10-5 South oil and gas field is located in the Beibu Gulf of the South China Sea, within an average water depth of 37 meters.

Xu Changgui, CNOOC’s Chief Geologist, commented: “In recent years, CNOOC Limited has consistently intensified theoretical innovation and tackled key technology challenges in buried hills and deep plays exploration. Breakthroughs have been achieved in the exploration of Paleozoic granite and Proterozoic metamorphic sandstone and slate buried hills within the Beibu Gulf Basin.

“They demonstrate the vast exploration potential in buried hills formations, drive the secondary exploration process in mature areas, and mark the commencement of large-scale exploration of buried hills in the Beibu Gulf Basin.”

The Chinese giant boosted its production levels last month by bringing online an oilfield development project in the South China Sea weeks after doing the same at another development in the western Pearl River Mouth Basin, and finding more oil in the eastern South China Sea.