A China National Petroleum Corp. (CNPC) subsidiary has made a giant oil and natural gas discovery totalling an estimated 1 billion tons of reserves in the prolific Tarim Basin in northwestern China, according to reports.

“This has been the largest discovery of oil exploration in the Tarim Basin in the recent decade,” Tarim Oilfield Co.’s Yang Xuewen, general manager, reportedly told Chinese outlet CGTN. Tarim Oilfield is a subsidiary of CNPC.

The discovery was said to be at the Manshen No. 2 well in the Fuman oilfield. The massive resource was reported after six years of exploration work and drilling 56 100-ton wells, CGTN reported. 

The well was drilled to a depth of 8,470 meters and encountered a 550-meter oil test column, according to reports. CGTN said the well set...