China National Offshore Oil Corporation announced on Sunday the discovery of the world's largest metamorphic rock oilfield in the deep layers of China's Bohai Sea.

The Bohai 26-6 oilfield has achieved record-breaking production levels, with newly proved oil and gas reserves exceeding 40 million cubic meters, leading cumulative proven reserves of the field beyond 200 million cubic meters and making it the largest metamorphic rock oilfield worldwide, it said.

With an average water depth of 22.1 meters, the Bohai 26-6 oilfield, situated in the southern part of the Bohai Sea, has been under continuous exploration since its discovery in 2023, significantly expanding reserve scale ever since.

Metamorphic reservoir petroleum refers to the oil and gas stored in metamorphic reservoirs. It is a special type of petroleum whose oil-reserving rock has been subject to weathering corrosion or tectonic deformation.

It is estimated that the oilfield can yield over 30 million cubic meters of crude oil while producing over 11 billion cubic meters of natural gas, it said.

The reservoir of the Bohai 26-6 oilfield is buried deep beneath the seabed, at depths of several kilometers, primarily composed of metamorphic rock. Over 80 deep wells drilled by several well-known international oil companies in similar regions previously failed to make significant discoveries, said CNOOC.