The deep oil exploration technology developed by Shaanxi Yanchang Petroleum Group has helped discover 831 million metric tons in new oil reserves in Shaanxi province's Yanchang oilfield, Shaanxi TV reported on Monday.

The technology helped discover new oil reserves in an oilfield that has been mined for more than 100 years. Yanchang oilfield is located in the Ordos Basin that lies in northern Shaanxi and neighboring Inner Mongolia autonomous region. Wang Xiangzeng, deputy manager of the oil group, said the oilfield has been known as one of the most difficult oilfields to mine in the world. With the newly discovered oil reserves, the group expects 2.1 million tons of oil output annually. It will further exploit deep oil reserves with the technology.