There is definitely something big hiding beneath the Appalachians, but it might not be what you'd expect.

The Wall St. Journal reported last October that the Marcellus Shale region under Pennsylvania and West Virginia is producing more natural gas than all of Saudi Arabia. It's pumping out 12 billion cubic feet per day, six times the production rate of five years ago, according to the U.S. Energy Information Administration (EIA).

The EIA went on to point out that the current rate is the equivalent of producing 2 million barrels of oil each day. Jerry Engelder, a geologist at Penn State University, predicted that the Marcellus could reach the 12 billion cubic foot rate, but he thought it would take two more years of work to get there. At the time, critics called his estimate far too optimistic.

Now, U.S. Capital Advisors has gathered all the relevant numbers and issued a study on the economic potential of the Appalachian Basin in terms of gas production. The researchers summed up their conclusions about investment in the region succinctly: "Why Appalachia? It's the biggest, baddest basin there is when it comes to gas production and the gift that keeps on giving, even in a $4 gas environment."

Based on a modest assumption of U.S. gas consumption growth of around 2 percent per year, Appalachia could easily account for almost one third of U.S. gas production by 2020.

Moving on to discuss the Marcellus Shale region specifically, U.S. Capital Advisors identified the area as having the best economics in the business. The gross resources can break even at gas prices of $3 or below. That means the current prices are bringing a 50 percent IRR to investors.

"So the bottom line is even with higher costs, the Marcellus will still be the driving force of the U.S. gas supply for many years to come," the report stated.

Appalachia even made the cover of May's American Oil & Gas Reporter (OAGR), with a story detailing the geology behind why there is so much shale gas built up beneath the Marcellus region.

"The Marcellus Shale weighs in with more than 500 trillion cubic feet of gas in-place spread over a four state area," reports the OAGR. "Continuous natural gas accumulations such as the Barnett Shale produce more than 10 percent of the gas in place, which when applied to the Marcellus Shale, translates to a resource that will return 50 Tcf in time.”

The rush is certainly on as companies seek positioning in the new energy supply order. Before 2003, there were practically no wells in the Marcellus shale. Today, they number in the thousands.

The Appalachians hold even greater potential in reserve, however. Just a few thousand feet beneath the Marcellus lies an untapped resource in the Utica Shale. This section of rock is much thicker and extends over a wider geographic region. The Utica Shale is many years from being explored because there is so much that has yet to be extracted from the layers above it.

When the time comes, the Utica Shale may end up being of far greater commercial value. Although drilling deeper for the Utica Shale will increase costs, the infrastructure being built today for the Marcellus, including permits, drill pads, pipelines and transportation will already be in place.

Beyond that, the big, bad basin may yet have some more surprises in store.