(Hong Kong, November 12, 2026) CNOOC Limited (the “Company”, SEHK: 00883 (HKD Counter) and 80883 (RMB Counter), SSE: 600938) today announced that it has drilled and discovered a high-yield volcanic oil and gas well in ultra-deep formations over 5,000 meters deep in Bohai, marking a major breakthrough in ultra-deep natural gas exploration offshore China.

The well is located in central Bohai, adjacent to the Bozhong Sag, the largest hydrocarbon-rich sag in Bohai. It encountered a cumulative total of over 120 meters of gas pay zone in volcanic formations, and was completed at a depth of 5,770 meters. The well was tested to produce approximately 800,000 cubic meters (approximately 28 million cubic feet) per day of natural gas, revealing promising exploration prospects in the offshore ultra-deep volcanic rocks and effectively promoting the natural gas exploration process in the Bozhong Sag.

The ultra-deep formations in Bohai are geologically complex, making reservoir prediction difficult. CNOOC Limited has continued to make breakthroughs in its theoretical understanding of offshore ultra-deep oil and gas exploration, independently developed key offshore deep multi-source broadband three-dimensional (3D) seismic exploration technologies, and developed innovative methods for predicting high-quality reservoirs in ultra-deep buried hills, precisely identifying the favorable ultra-deep volcanic natural gas enrichment zones in the Bozhong Sag, discovering a high-yield oil and gas well, and marking a significant breakthrough in ultra-deep volcanic natural gas exploration in Bohai.

Mr. Xu Changgui, Chief Scientist and Chief Geologist of China National Offshore Oil Corporation (CNOOC), said, “In recent years, CNOOC Limited has continued to strengthen theoretical innovation in deep and ultra-deep oil and gas enrichment in basins with high heat flow and strong activity, and to intensify research on key technologies. Exploration in China’s offshore areas has achieved a major leap from shallow to deep and ultra-deep formations. The success of this well has opened up a new play for offshore ultra-deep natural gas exploration and expanded the scope of deep oil and gas exploration in Bohai. It is of positive significance for accelerating the ultra-deep exploration process in Bohai and for building a major gas province of one trillion cubic meters in Bohai.”