The plunge in crude prices all but killed profits at China’s top energy producer and its largest oil refiner. PetroChina Co. on Thursday reported its worst quarterly profit on record, with net income for the three months ended September plunging 81 percent from a year ago to 5.2 billion yuan ($818 million). An increase in refining revenue failed to stanch a 92 percent drop in earnings at China Petroleum & Chemical Corp. Net income at Asia’s biggest refiner, known as Sinopec, was 1.64 billion yuan. Both posted less than half what analysts expected. “Falling oil prices really put those companies under tremendous pressure,” Neil Beveridge, an analyst at Sanford C. Bernstein & Co., said by phone from Hong Kong. “Moving forward, they have to continue to find ways to cut costs and improve efficiency and make themselves more competitive.” Damage from dropping oil prices has been almost inescapable for […]