PetroChina, one of China’s big-three oil companies, announced in a statement released in mid-April that its production inched up in the first quarter, underscoring its need to find new sources of oil. Despite increase of investment for on oil exploration, PetroChina said its oil and gas output rose just 3.3 percent to 229.1 million barrels of oil equivalents in the January-March period of this year. That PetroChina, one of China’s big-three oil companies, announced in a statement released in mid-April that its production inched up in the first quarter, underscoring its need to find new sources of oil. Despite increase of investment for on oil exploration, PetroChina said its oil and gas output rose just 3.3 percent to 229.1 million barrels of oil equivalents in the January-March period of this year. That