The report underscores the voracious energy needs of Asia's economic powerhouse, as a growing middle class migrates to car ownership. Although China ranks fourth globally in crude oil production, according to data from the Energy Information Administration, it's not enough to slake the country's implacable thirst for energy.



"China is a big importer of crude," said Gary Clark, a London-based commodities strategist at Roubini Global Economics. "At same time domestic (Chinese) production is plateauing. It requires them to go offshore if they want to make up that depleted oil."

According Wood Mackenzie data, China has become more dependent on OPEC oil volumes, with the cartel's Chinese flows going from less than $20 billion in 2004 to about $140 billion in 2012. That rivals the revenue OPEC derives from the U.S., which has shrunk from a peak of around $190 billion in 2008.

As the U.S. produces its own oil and gas, U.S. oil import volumes have declined to 4 million barrels per day (bpd). Meanwhile, China's have gone in the other direction, up from about a million bpd in 2004 to more than 3 million last year.

The United States is producing more energy in a way that economists say lessens its own need to import oil, even if it hasn't yet made the world's largest economy fully self-sufficient.

"Admittedly, the U.S. may never achieve full energy independence and, regardless of the legal obstacles, is unlikely ever to be a significant exporter of crude oil. But net imports of crude could still fall further too," Capital Economics said in a research note this week, adding that the U.S. boom can help contain crude prices globally.

Yet China's import story has broad implications for its domestic economy, which is running headlong into stubborn macroeconomic realities. The country is prone to bouts of inflation, and until recently has enjoyed one of the world's largest trade surpluses.

By importing more energy, China could make itself more vulnerable to price pressures from fluctuating crude prices, and further erode a trade balance that plunged 29.6 percent year over year in July. It comes as China has been dogged by perceptions that its economic growth is unsustainable, with foreign investment slowing down.

"We expect investment's going to give out and rebalance more toward consumption," said RGE's Clark. Simultaneously, "over time, oil demand is going to remain strong, and imports will remain strong. That should deplete the trade surplus," he added.

—By CNBC's Javier E. David.