Zhu Guowen, executive director of Daqing Oilfield Co, said, "This was a significant milestone in China's industrial history and the nation's efforts to ensure energy security," adding that to date, the nation's largest onshore oilfield has paid more than 3 trillion yuan ($410.7 billion) in taxes and other fees.

The company said the oilfield produced 30 million tons of crude oil and 5.54 billion cubic meters of natural gas last year, with its gas production rising for the 12th consecutive year.

Daqing Oilfield Co has innovated and developed world-leading technologies for the development of onshore sandstone oilfields, leading the nation among its peers in terms of high-quality development.

The oilfield, which had an annual crude output of more than 50 million tons from 1976 to 2002, has been hailed by many observers as a miracle in the history of oilfield development.

Since 2003, despite shrinking reserves — a common problem among older oilfields — Daqing has strengthened on-site management and improved production control with the help of new technology.

Laborious work

Daqing's annual tertiary oil recovery exceeded 10 million tons over the past 21 years, with the company boasting a total production of 300 million tons to date, making it the largest center globally for research in tertiary oil recovery and the largest site in the world using such technology.

The company said it has achieved more than 11,000 technical innovations and inventions, including over 120 national-level science and technology awards, one first prize and three grand prizes in the National Natural Science Award.

To boost productivity in an all-around way and better take part in the Belt and Road Initiative, the company has been involved with numerous energy projects overseas, including oil and gas fields, pipelines and power stations. Its oil exploration teams have visited more than 50 countries and regions, including Venezuela, Egypt and Sudan.