China’s CNOOC reports breakthrough in metamorphic buried-hill exploration in South China Sea

China National Offshore Oil Corporation (CNOOC) has achieved a major breakthrough in deep metamorphic buried-hill exploration in the South China Sea, marking the first successful discovery of metamorphic sandstone and slate buried hills in China's offshore waters, Securities Times reported on Wednesday.

CNOOC reported that exploratory well WZ10-5S-2d at the Weizhou 10-5 South oil and gas field, located in the Beibu Gulf of the northern South China Sea, encountered 211 meters of oil and gas-bearing formations.

The exploration significantly guides and demonstrates the development of deep and buried hill oil and gas exploration in China, said Zhou Xinhuai, CEO of CNOOC, according to Beijing-based Securities Times.

CNOOC will further intensify efforts in key theories and technologies for deep oil and gas exploration and development, enhance independent innovation in science and technology, steadily advance oil and gas reserve growth and production, and ensure a stable energy supply, Zhou added, as he was cited by Securities Times.

Xu Changgui, Chief Geologist of CNOOC, noted that the company has recently intensified theoretical innovation and addressed key technological challenges in complex exploration areas such as deep formations and buried hills. In the Beibu Gulf Basin, CNOOC has achieved major breakthroughs in exploring Paleozoic granite and Proterozoic metamorphic sandstone and slate buried hills.

These advances highlight the vast potential for exploration in buried hill formations, support secondary exploration in mature oilfields, and mark the official start of large-scale buried hill exploration in the basin, Xu said, Securities Times reported.

Lin Boqiang, director of the China Center for Energy Economics Research at Xiamen University, told the Global Times on Wednesday that with continuous advancements in exploration technologies, the South China Sea is expected to yield increasingly abundant oil and gas resources, offering stronger support for China's energy security. 

At present, China is actively exploring resources in the South China Sea, achieving major breakthroughs every year. With the improvement of technologies, fields that were once difficult to detect are now gradually being identified, Lin said.

China's total oil production remains stable while natural gas output continues to rise. From an economic perspective, the country can increase output when oil prices are high. From an energy security standpoint, more production of domestic oil and gas resources will enhance self-sufficiency and better safeguard national energy security, Lin added.

China's oil and gas supply continues to grow steadily. According to data released by the National Bureau of Statistics, oil and gas production maintained stable growth in the first half of 2025.

The country's capacity to ensure energy supply has improved significantly. In the first half of this year, with large-scale industrial crude oil output reached 108 million tons, up 1.3 percent year-on-year. Industrial natural gas output hit 130.8 billion cubic meters, reaching a record high, representing a 5.8 percent year-on-year increase.