CNOOC's drilling platform on China's Bohai Sea Photo:VCG

The Bohai Sea oilfield, China's largest crude oil base, had produced a cumulative total of oil equivalent exceeding 500 million tons as of Monday, after it has been in operation for more than 50 years.

"The 500 million tons of oil equivalent can meet the basic needs of 1.4 billion Chinese people for a year, and can be used by a megacity like Tianjin with a population of over 10 million for nearly a century," media reports said on Monday, citing Wang Yu, a production manager of the Tianjin branch of China National Offshore Oil Corp (CNOOC).

The term "oil equivalent" is used to facilitate like-for-like comparisons in the energy industry. One barrel of oil (159 kilograms) is generally deemed to have the identical amount of energy content as 6,000 cubic feet (0.03 cubic meters) of natural gas.

Located in the hinterland of the Beijing-Tianjin-Hebei region in North China, the Bohai field has cumulative proven geological reserves of more than 4.4 billion tons of oil and nearly 500 billion cubic meters of natural gas.

In 2021, the output of crude oil from the field reached 30.132 million tons, accounting for about 15 percent of China's overall annual crude oil output. China produced 198.98 million tons of crude oil in 2021 and imported 512.98 million tons of crude oil, becoming the second-largest crude oil consumer in the world.

Over the past 50 years of operation, the Bohai field has built more than 50 oil and natural gas fields and more than 180 production facilities. It is operated by CNOOC, which started development in 1965. 

The field aims to produce 40 million tons of crude oil annually, build a trillion-cubic-meter level gas field in the Bohai and Yellow Sea, and remain the largest crude oil production base in China, said Yan Hongtao, general manager of CNOOC's Tianjin branch.

The annual oil and gas production of the Bohai Sea oilfield in 2025 is set to surpass 40 million tons, according to CNOOC's seven-year work plan (2019-25).

So far under the plan, four oil fields with reserves of more than 100 million tons have been discovered, and 85.35 million tons of oil and 9.15 billion cubic meters of natural gas had been extracted by 2021.