Prepare for superlatives if you talk to BHP Billiton, the world's biggest miner, about the shale energy revolution.

Looking at BHP's shale investments in a better light

"This is absolutely stupendous," says Mike Yeager, chief executive of its petroleum division and a 35-year energy industry veteran. "This is the biggest thing that has happened in my career."

For once, the company line could be an understatement. The shift taking place in the energy industry is of a scale to rival anything seen in several decades, say industry watchers. As one puts it: first there was nuclear, then China's growth explosion - and now shale.

What that refers to is the resource-rich shale rock that was formed from the "muddy gumbo", as Yeager puts it in his Texan drawl, which lay at the bottom of ancient oceans. Today, it sits beneath traditional oil and gas reservoirs, for which the shale rock is often the source.

Advertisement That the shale itself held riches has been known for years, but the large-scale extraction of its oil and gas has been made practical only recently, by developments in hydraulic fracturing or "fracking" - shattering the rock and flushing it with liquid to encourage the oil and gas to flow out - and horizontal drilling, allowing vastly increased access to the seams of shale underground.

The implications for the world's biggest economy are profound, since it happens to be endowed with the stuff. US natural gas resources are now put at over 1300 trillion cubic feet - the bulk of which is shale gas - edging ahead of Russia's near 1200 trillion cubic feet of gas.

As for oil, total US liquid production is forecast to average 11.4 million barrels a day next year, close to Saudi Arabia's current average of 11.6 million. As Yeager notes, the US also enjoys helpful factors including "supportive" regulators, shale riches lying in areas boasting "more cows than people" and a system which hands landowners the royalties, incentivising them to accept drilling.

What that all adds up to is a major ramp-up in industry activity over the past three years. Because of shale, the International Energy Agency this week announced the US will overtake Saudi Arabia as the world's top oil producer by 2017, and overtake Russia as the biggest gas producer even sooner - by 2015.

Nimble entrepreneurs

Like any gold rush, the beginnings of this shale revolution were dominated by nimble, entrepreneurial operators. However the big players have the resources to catch up, and are doing so.

BHP, the Anglo-Australian mining colossus, has only been in the shale arena for 18 months, but by spending some $US20 billion buying up assets it has key positions in four major US shale formations: Fayetteville, Haynesville, Permian and Eagle Ford. Across this acreage, it has 45 drilling rigs busy sinking wells, the bulk of which are at Eagle Ford, a 645-kilometre-long and 80-kilometre-wide streak of shale under south Texas. It is now the biggest oil field development in the world, and BHP holds the second-strongest position.

But every revolution must have its losers too, and in the shale phenomenon they are still being decided. With landowners savvy about negotiating mining royalties of up to 25 per cent of the shale revenues, stories of people owning just "one cow, and they now live in the Ritz-Carlton" abound, says Yeager.

But that is not to say there is no push-back. Headline concerns around fracking may focus on people setting fire to what comes out of their taps and fears about earthquakes, but locals are more bothered about the dust clouds and road damage from the huge trucks rolling to and from the shale gas operations.

In DeWitt County, currently hosting 21 of the rigs in operation at Eagle Ford, the county judge says he is facing a $432 million bill for road repairs and upkeep. DeWitt is home to just 20,000 people.

Fracking areas

The industry has to tread a careful line to make sure it all stays worth the while of those living in fracking areas.