The boom in North American shale oil could expand even faster than forecast if the crude is produced responsibly, energy experts said.  The National Petroleum Council recently forecast that some 3 million barrels per day of shale oil could be produced in North America by 2035 if regulations were favorable to the industry.

The shale oil surge in Bakken, North Dakota and other areas of the country are estimated to be about five years behind the natural gas shale boom. Rapid advancements in hydraulic fracturing, or fracking, and directional drilling have boosted output of both fuels.

"My personal feeling is it could be earlier than 2035 that we get to (3 million bpd) given the pace of development we are seeing in places like the Bakken and increasingly in other arenas," Andrew Slaughter, a business advisor at Shell Exploration & Production Company, told a panel at the Center for Strategic and International Studies.

The surge could threaten Saudi Arabia's dominant role in world oil markets, and it also eases the urgency to develop the kingdom's own reserves, its state energy company said last month.

The U.S. Energy Information Administration on Tuesday raised its forecast for 2012 liquid fuel output by 37% on faster growth from shale oil.

Bakken, which began producing in the early 2000s after being discovered in the 1950s, is yielding about 450,000 barrels per day, or about 8% of U.S. crude output.

Another shale oil deposit, known as Eagle Ford in Texas, is potentially even more profitable, said Danny Brown, a general manager at Anadarko Petroleum Corp.

There are also 14 or 16 other shale oil fields in North America that are in the early stages of development.

Like fracking for natural gas, shale oil has raised the hackles of environmentalists.

In the fracking process companies blast large amounts of water, mixed with chemicals and sand, deep underground to release the fuels.

Environmentalists are concerned the process uses large amounts of water and employs potentially dangerous chemicals that could contaminate the ground water. In the shale oil, they also abhor companies flaring off large amounts of natural gas in the process, leading to excess emissions.

James Sorensen, a research manager at the Energy & Environmental Research Center in North Dakota said companies could ease those concerns by recycling water and by stopping the flaring.