You know a lot by now about the spreading exploration and production for unconventional natural gas in our country, along with its dampening effect on gas prices in the U.S. and, to some extent, worldwide.

But perhaps you didn't know the magnitude of the gas likely trapped in gas-rich national plays such as the Barnett shale of Texas, the Haynesville, which straddles Texas and Louisiana, and the Marcellus play in much of our nation's Northeast. According to the U.S. Energy Information Administration, the drilling of unconventional gas wells in just the past year has gunned estimates of our recoverable unproved shale gas reserves from 353 trillion cubic feet to 827 trillion today.

Can you really benefit from unconventional gas?
That increase is impressive. But a few key questions about shale gas and its use deserve our attention. The first involves whether the shale gas phenomenon will spread to other continents or remain a largely U.S. phenomenon. Next, we'll consider the optimum ways to use our new natural gas stash for the benefit of our economy and our nation's energy security. And finally, we'll look at the likelihood that environmental concerns could ultimately slow future shale gas development.

After that, we'll think about the most advantageous ways for Foolish investors to take advantage of the burgeoning shale play.

The first query -- regarding the potential for locating shale gas in other parts of the world -- was clarified somewhat late last month when an exploratory well being drilled by India's state-owned Oil and Natural Gas Corp. flowed gas from the Barren Measure shale near Durgapur, in West Bengal. As of now, that country's shale targets appear to be located in the Damodar, Cambay, Krishna Godavari, and Cauvery basins.

Four exploratory, or "science," wells are in the works in the Damodar basin, along with others in the country. A key role is being played in those efforts through the help of Schlumberger (NYSE: SLB), which has benefited in India from its experience in the United States.

Who's playing the shale game?
At the same time, you probably know that several foreign companies have invested in U.S. shale plays. And now Italy's Eni (NYSE: E), working with the China National Petroleum Corp. -- the parent of PetroChina (NYSE: PTR) -- will also call upon its own U.S.-gained expertise for unconventional exploration in Chinese-owned assets.

As for Europe, Schlumberger CEO Andrew Gould says that, for financial, logistical, social, and regulatory reasons, looking for unconventional gas in Europe could be "very different from doing so in the southern United States." As he also noted that some of the potential problems in Europe are environmental, since up to 80% of the water used during the hydraulic fracturing process is not recovered. Beyond that, according to one European researcher, the continent just may have the "wrong rocks" in places.

Furthermore, it appears that much of Western Europe is characterized by shale plays that are deeper and smaller, with higher clay contents than those in the United States. Such trends tend not to be beneficial to those searching for shale gas. Nevertheless, farther to the east, because of Ukraine's potentially dangerous dependence on Russian gas, the country's energy minister has said that the country is ready to approve appropriate legislation to provide incentives for companies to search for shale gas within its borders.

The key usage question
But let's move along to the optimum usage for natural gas. It appears that there are two key applications where natural gas can have the most beneficial impact: power generation and transportation.

According to ExxonMobil's (NYSE: XOM) newly released Energy Outlook -- and probably not surprising to Fools, who tend to be brighter than most folks -- in the production of electric power, the use of gas "results in up to 60% percent fewer CO2 emissions than coal." In that connection, Outlook also pointed out that, "Natural gas demand is rising in every region of the world but growth is strongest in non-OECD (developing) countries, particularly China, where demand in 2030 will be approximately six times what it was in 2005."   

And then there's the use of gas to power automobiles and trucks. According to Sergio Marchionne, the CEO of Italy's Fiat, which has an 80% market share of methane-powered care in Europe and a 55% share of light commercial vehicles, compared to the plug-in electric cars that General Motors (NYSE: GM) and Ford (NYSE: F) have adopted for their primary concentration, natural gas vehicles are both more affordable and result in fewer obstacles for wide-scale adoption.

Turning to the world of trucks, as I told you not long ago, Indiana's Cummins (NYSE: CMI) is manufacturing compressed natural gas and liquefied gas engines that provide comparable power, and vastly improved environmental benefits to diesel engines. Indeed a Canadian food hauler recently ordered 180 liquefied natural gas trucks from Texas-based Peterbilt.

On the environmental front, there has been more significant concern about the effects of the fluids used in hydraulic fracturing, or fracking. In this process, companies drill to the shale and then blast a mixture of water, sand, and chemicals into the well bore to break up the rock and free the trapped gas or oil. In the face of concern that the chemicals used in the process stand to poison the nearby water tables, the companies may be required to disclose the composition of their fracking fluids. But more positively, the companies are in the nascent stages of formulating their fracking chemicals from safer ingredients, such as those used in food additives.

The bottom line
So there you have it, except for some thinking about the best place for your shekels in the unconventional gas boom. For my money, you needn't become too elaborate. Exxon, for instance, is both a major global producer of crude oil and the largest U.S. gas producer -- thanks to its 2010 acquisition of XTO Energy. At the same time, Schlumberger is the biggest of the oilfield services contingent, and, as has been demonstrated in India, offers the sort of experience that producers desire.

Both of these well-managed, technically sophisticated, and geographically diverse companies merit your attention amid an energy world that is becoming progressively more demanding and complex.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.