Bozhong 26-6 in Bohai Sea, the largest metamorphic rock oilfield worldwide, began drilling, April 24, 2024. (Photo/China News Service)

Bozhong 26-6 in Bohai Sea, the largest metamorphic rock oilfield worldwide, began drilling on Wednesday, according to China National Offshore Oil Corporation.

Situated in the waters of southern Bohai Sea, about 170 kilometers from northern coastal city Tianjin, the Bozhong 26-6 oilfield has proven oil and gas reserves over 200 billion cubic meters.

With an average water depth of more than 22 meters, the oilfield newly confirmed reserves of oil and gas exceeding 40 million cubic meters in 2024.

It is estimated that the oilfield can extract over 30 million cubic meters of crude oil, meeting the daily transportation needs of a million residents for more than 20 years.

Over 11 billion cubic meters of gas can be yielded from the oilfield, satisfying the household gas demand of a million urban residents for more than 60 years.

Wells in the Bozhong 26-6 oilfield have an average depth of 4,835 meters with the largest reaching 5,049 meters. It is expected to drill more than 160,000 meters, equivalent to drilling through 18 Mount Qomolangma

Reservoirs of the Bozhong 26-6 oilfield are buried in seabed hills thousands of meters below the surface. They are mainly composed of metamorphic rock, said Liu Baosheng, manager of the Tianjin branch of China National Offshore Oil Corporation.

Metamorphic rock comprises mainly high density granite, with an average compressive strength of 137-275 megapascal, nearly 9 times that of concrete, and even higher than that of cast iron. The formation temperature reaches 178 degrees Celsius, according to Liu.