CNOOC Limited announced on Tuesday that Mero4 Project, located in the Santos Basin pre-salt southeastern offshore Brazil, about 180 kilometers from Rio de Janeiro, has recently commenced production.

Located at a water depth of between 1,800 and 2,100 meters, the project will be developed by the traditional deep-water Pre-salt development mode, FPSO+Subsea. A total of 12 development wells are set to be commissioned, including 5 oil producers, 6 water or gas alternate injectors and one convertible well, it said.

To maximize production, the wells are equipped with intelligent well completion technology, enabling remote switching between production and the injection wells via the platform.

The FPSO, or floating production, storage and offloading, used in Mero4 is one of the largest FPSOs in the world, It was integrated in China in December 2024 and arrived at the oilfield in March 2025. The FPSO is able to produce up to 180,000 barrels of crude oil, process 12 million cubic meters of natural gas per day and inject 250,000 cubic meters of water, which will increase the installed production capacity of Mero field to 770,000 barrels of crude oil per day, it said.

To implement the concept of green and low carbon development, Mero4 project is also equipped with resources to operate the HISEP (High Pressure Separator), which allows underwater separation of extracted oil and the associated gas and reinject the gas into the reservoir. The HISEP will simultaneously boost production and reduce emission.