A “major” discovery in the South China Sea’s Huizhou 19-6 oilfield was revealed by CNOOC Ltd. on Monday. The field’s proved in-place quantities have increased to more than 100 million metric tons of oil equivalent thanks to Well HZ19-6-3.  The discovery well yielded 2.41 million cubic feet of natural gas per day and 413 barrels of oil per day during testing.  According to a press release from the state-backed oil and gas exploration and production business, the well, which was drilled to 5,415 meters (17,765.75 feet), came across 127 meters of oil and gas pay zones

Huizhou 19-6 sits in the eastern South China Sea at an average water depth of about 100 meters. “The main oil-bearing plays are Paleogene Enping Formation and Wenchang Formation, and the oil property is light crude”, said CNOOC Ltd., majority-owned by China National Offshore Oil Corp. (CNOOC).

CNOOC Ltd. chief geologist Xu Changgui commented, “In recent years, CNOOC Limited has strengthened the research on exploration theory and technology of the deep and ultra-deep plays in the South China Sea, and breakthroughs have been achieved”.

“This discovery has confirmed the largest integrated clastic oilfield in the northern South China Sea in terms of original oil in place, breaking the traditional theoretical understanding, and demonstrating the enormous exploration potential of deep and ultra-deep plays in high-temperature and highly active basins offshore China”, Xu added

CNOOC Ltd. chief executive Zhou Xinhuai noted, “Oilfields with hundred-million-ton oil in-place have been discovered in this area for two consecutive years, making it a new driver of the offshore oil and gas production growth”.

HZ19-6-3 is the second discovery declared by CNOOC Ltd. this year, following WZ10-5-1Sa in the Weizhou 10-5 field.

After drilling a total depth of about 4,840 meters in an area with an average water depth of 37 meters, WZ10-5-1Sa showed a pay zone of 283 meters. During testing the well produced around 13.2 million cubic feet of gas and approximately 800 barrels of petroleum per day.

“It marks a major breakthrough in natural gas exploration in the granite buried hills in the Beibu Gulf Basin”, CNOOC Ltd. said March 6, using the local name for the Gulf of Tonkin.

Xu said, “The Weixinan Sag in the Beibu Gulf Basin is one of the most explored sags offshore China”.

“In recent years, the Company has been researching the reservoir formation theories of the complex buried hills and the relevant technologies needed”, Xu said. 

“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”.

The company made 11 oil and gas discoveries and appraised 30 oil and gas structures across its global portfolio last year. At the end of 2024 its net proven reserves reached 7.27 billion barrels of oil equivalent, up 7.2 percent year-on-year, the company said in its report of annual results Thursday.

“CNOOC Limited continued to innovate exploration theories and technologies”, the report said. “In China, multiple discoveries were made under the guidance of the exploration theories, including Longkou 7-1, Qinhuangdao 29-6, Huizhou 19-6, and Lingshui 36-1.

“Overseas, the Company expanded its global exploration footprint along the Atlantic rim and the ‘Belt and Road’ countries. This year, CNOOC Limited was awarded petroleum contracts for 10 exploration blocks in Mozambique, Brazil and Iraq”.