China is expected to surpass the US as the world's largest oil importer by 2017, and the opposing trend of growing crude oil imports by China and falling imports by the US will affect inter-regional trade flows and the cost to both countries, consultants Wood Mackenzie said Tuesday.

According to WoodMac's estimates, China will need to spend $500 billion on oil imports by 2020, while US spending on oil imports will fall to $160 billion by the same year.

"By 2020, 70% of China's oil demand will come from imports. On the other hand, US import requirements will reduce due to tight oil production," said William Durbin, WoodMac Beijing-based president of global markets.

From 2005 to 2020, China's oil imports will rise from 2.5 million b/d to 9.2 million b/d, while US imports will have fallen from a peak of 10.1 million b/d to 6.8 million b/d within the same period, WoodMac said. That translates to a 360% increase in China's crude oil imports and a 32% decline for the US.