China announces major oil, natural gas deposit reserve discovery in Beibu Gulf Basin

China’s state-owned oil and gas company has announced a major hydrocarbon discovery breakthrough in the exploration of Paleozoic buried hills in the Beibu Gulf Basin.

The China National Offshore Oil Corporation (CNOOC) made the announcement on Thursday.

The breakthrough came after drilling was done to a total depth of about 15,879 feet (4,840 meters) in an area with an average water depth of about 121 feet (37 meters).

The company’s exploration initiative struck upon a crude oil and natural gas pay zone of 928 feet (283 meters), as per the press release.

The state-owned company claims to be the largest offshore producer of petroleum and natural gas.

Oil and gas reserve discovery in China

As per CNOOC, the Weizhou 10-5 oil and gas field is located in the Beibu Gulf of the South China Sea.

The discovery marks a major breakthrough in natural gas exploration in the granite buried hills in the Beibu Gulf Basin.

The results of the test conducted by the company indicate that the well can produce approximately 13.2 million cubic feet of natural gas and about 800 barrels of crude oil per day, as per a press release by the company.

The Weixinan Sag in the Beibu Gulf Basin is one of the most explored sags offshore China.

In recent years, CNOOC has been researching on the reservoir formation theories of the complex buried hills and the relevant technologies needed, as per Xu Changgui, the Chief Geologist of the company.

“The breakthrough in the exploration of Paleozoic granite buried hills reveals the vast exploration prospects of the buried hills in the Beibu Gulf Basin. It will also provide guidance for exploration in similar fields offshore China,” Xu added.

Zhou Xinhuai, the CEO of CNOOC, said, “In recent years, the Company has made large and medium-sized oil and gas discoveries in various types of buried hills offshore China, which have been further expanding the Company’s oil and gas resource base.”

“The discovery in the Beibu Gulf Basin will help to stabilize energy supply and continuously contribute to the economic and social development.”

Past breakthroughs from CNOOC

In February 2025, CNOOC had announced the start of production from Bozhong 26-6 Oilfield Development Project (Phase I) in central Bohai Bay.

The project is expected to achieve a peak production of approximately 22,300 barrels of oil equivalent per day in 2025. The oil property is light crude.

CNOOC had said that Bozhong 26-6 Oilfield is the world’s largest metamorphic buried hill oilfield with cumulative proven oil and gas in-place of over 200 million cubic meters.

One of the other unique things about the project is that it uses technology to capture and separate the associated carbon dioxide from crude oil extraction and reinject it back into the formation to drive the oil, thereby increasing production while reducing emissions.

The project is expected to bury approximately 1.5 million tons of carbon dioxide throughout its life cycle. The project was being fully overseen and operated by CNOOC.