Drilling of the "Dabei-401" well, designed to be China's deepest onshore gas well, has started on Tuesday in the country's northwestern Xinjiang Uygur Autonomous Region.

The well to drill to a depth of 8,457 meters is located in the southern foot of the Tianshan Mountains, where the geological structure is extremely complex, according to the Tarim Oilfield of China National Petroleum Corporation (CNPC), China's leading oil and gas producer.

The data of its adjacent wells show that the formation pressure in the area is close to 140 MPa.

The Tarim Oilfield said it is expected to drill 110 ultra-deep wells this year, while it drilled 23 wells with a depth of over 8,000 meters in 2021.

Tarim Basin is a major petroliferous basin in China, producing one-sixth of the country's total production of natural gas.