Storyline: China achieves breakthrough in offshore heavy oil thermal recovery [Voice_over] Officials from the China National Offshore Oil Corporation, CNOOC, have announced a milestone for the company: a cumulative output of offshore heavy oil thermal recovery that tops five million tons. Heavy oil is crude that's thick, viscous and notoriously difficult to extract. Typically, it's removed using various thermal recovery methods which can be costly and require special equipment So far this year, China's total offshore heavy oil thermal recovery output exceeds 1.3 million tons, with CNOOC officials predicting it will top 2 million tons by the end of the year. China is one of the world's few major heavy oil producers, with proven reserves of offshore heavy oil that requires thermal injection exceeding 600 million tons, accounting for 20 percent of the country's total heavy oil reserves. [Restrictions : No access Chinese mainland]