Aerial photo taken on Sept. 27, 2019 shows facilities at Daqing Oilfield in Daqing, northeast China's Heilongjiang Province. (Photo: Xinhua)

HARBIN, Aug. 25 (Xinhua) -- China's Daqing Oilfield, a subordinate of the China National Petroleum Corporation, announced Wednesday the discovery of a major shale oil field with predicted geological reserves of about 1.27 billion tonnes.