PetroChina Co, the listed arm of China's state-owned energy giant China National Petroleum Corporation(CNPC), has just discovered new reserves at an oilfield of more than 1 billion tons of oil, a significant boost to the nation's current oil reserves which will reduce dependence on imports, an expert said Monday.  PetroChina discovered the new reserves at the Qingcheng oilfield in the Ordos Basin, the company said in a filing it published on September 29.  The oilfield's added proven reserves stand at 358 million tons, while estimated reserves could reach 693 million tons, according to the ... (full story)