increase of 6.4% over 2006, according to CNPC’s Petroleum Industry Overview, 2007-2008.   China’s three main oil companies, CNPC, Sinopec and CNOOC, are beefing up their refining capacity as they prepare for long-term competition in the domestic oil products market. PetroChina aims to have 160 million tonnes of annual crude processing capacity of 2010. If…