CNOOC said the Lukanani and Ranger oil fields offshore Guyana have been successfully appraised, according to its 2025 annual report. CNOOC has a stake in the ExxonMobil-operated Stabroek Block, where those fields are located.
Ranger was first discovered in 2018, marking ExxonMobil’s sixth find in the Stabroek Block. The well is located about 60 miles northwest of the Liza field and was the deepest discovery made that year.
Initial estimates from Rystad Energy in 2018 placed Ranger at 346 million barrels of oil. The estimate was revised to 432 million barrels in 2022. S&P Global Platts later assessed the resource at between 500 million and 600 million barrels.
Ranger is located within a carbonate reservoir, a formation composed largely of marine organism fragments such as coral and algae.
The Lukanani discovery was announced in April 2022. The Lukanani-1 well encountered approximately 115 feet of hydrocarbon-bearing sandstone in water depths of 4,068 feet.
ExxonMobil began drilling the Lukanani-2 well in June 2025.
ExxonMobil is the operator of the Stabroek Block with a 45% interest. Hess Corporation also holds 45%, while CNOOC holds 20%. The operator has discovered an estimated 11 billion oil-equivalent barrels there, has lined up eight development projects, and is expected to increase oil production to 1.7 million barrels per day by 2030.
