(Hong Kong, March 6, 2025) CNOOC Limited (the “Company”, SEHK: 00883 (HKD Counter) and 80883 (RMB Counter), SSE: 600938) today announces that it has made a major breakthrough in the exploration of Paleozoic buried hills in the Beibu Gulf Basin.

The Weizhou 10-5 oil and gas field is located in the Beibu Gulf of the South China Sea, with an average water depth of about 37 meters. Exploration well WZ10-5-1Sa encountered an oil and gas pay zone of 283 meters, with a total drilled depth of approximately 4,840 meters. The test results indicate that the well produces approximately 13.2 million cubic feet of natural gas and about 800 barrels of crude oil per day. It marks a major breakthrough in natural gas exploration in the granite buried hills in the Beibu Gulf Basin.

Mr. Xu Changgui, the Chief Geologist of the Company, 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 on the reservoir formation theories of the complex buried hills and the relevant technologies needed. 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.”

Mr. Zhou Xinhuai, the Chief Executive Officer of the Company, 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.”