Staff members of No. 1205 drilling team pose for a group photo at a drilling rig in Daqing Oilfield in Daqing, northeast China's Heilongjiang Province, Sept. 28, 2019. Daqing Oilfield, discovered on Sept. 26, 1959, is the largest oilfield run by PetroChina and also the country's largest oil production base. The oilfield, once accounting for over half of China's total crude output, had an annual crude production of over 50 million tonnes for 27 consecutive years and over 40 million tonnes for 12 straight years. Its annual crude oil and gas output still remains over 40 million tonnes of oil equivalent, with proven oil reserves at 6.48 billion tonnes. Its annual natural gas output has exceeded 4 billion cubic meters. (Xinhua/Xie Jianfei)