Marcellus Shale: you’ve probably heard the name bandied about on the news. So who or what is Marcellus Shale? Well, it’s not a character from the Flintstones or the name of a Motown singer. It is named for a town in upper New York and can be found in formations of varying thickness beneath about 60 percent of Pennsylvania. Marcellus Shale is an enormous formation of sedimentary rock that spans the Appalachian Basin, running through areas in Virginia, Tennessee, Kentucky, and Maryland in the south and with larger formations beneath much of Ohio, Western Pennsylvania, and New York.
Marcellus Shale may be modern news, but is hardly something new. It was formed during the Devonian period, about 386-390 million years ago. At that time, many parts of what is now the northeastern United States lay submerged under water. Layers of mud were deposited over time on the seabed floor along with organic material. After ages of heat and pressure, the layers of mud compacted and formed shale. This process generated heat which helped turn all the buried organic matter into natural gas. Shale, unlike more porous rock formations such as sandstone, is impermeable, meaning the gas created by the organic matter remains trapped between the layers of the shale.
Natural Gas: A Lot or a Little?
Geologists have known for years that Marcellus Shale contains natural gas deposits, but it wasn’t until recently that technological advancements have made it the talk of the U.S. energy scene.
In 2002, the U.S. Geological Survey estimated that Marcellus Shale contains approximately 1.9 trillion cubic feet of gas. That sounds like a lot of gas, but spread over hundreds of miles, it didn’t generate much interest for exploration. Exploratory wells were drilled, but they didn’t yield enough volume to warrant the outlay of capital needed to explore further development.
However, all that changed in 2003 when speculators drilled a well in Washington County, yielding a promising flow of gas and turning Marcellus Shale into a sought after gas “play,” the industry term for an area targeted for exploration.
In 2008, Terry Englander, a geoscience professor at Pennsylvania State University, and Gary Lash, a geology professor at State University of New York at Fredonia shocked everyone with their estimate that the Marcellus Shale formation contained not 1.9 trillion cubic feet of gas but an astounding figure of more than 500 trillion cubic feet of natural gas, enough to supply the U.S. for a decade or more.
How to Drill Marcellus Shale
Because the gas is trapped between layers of shale, extracting it is not as simple as drilling a vertical well and tapping into the pocket of gas. A similar gas play known as the Barnett Shale in Texas proved the necessity for horizontal drilling and hydraulic fracturing, or “hydrofracing” methods to extract the gas. Simply put, a well is drilled vertically until it hits the shale bed and then the well is drilled horizontally.
Afterward, a portion of the well is then sealed off and then water or gel is injected into the well under high pressure, fracturing the shale. To keep the fractures from closing after the pressure is reduced, sand is pumped in propping open the fractures and releasing the gas into the well. The gas in the Marcellus Shale formation is generally a mile below the surface, which makes drilling for it very costly, but natural gas is desirable because it is clean-burning, and the Marcellus Shale gas play is doubly attractive because it is found not in our own backyards but under them.
Pennsylvania currently imports 75 percent of its natural gas and the proximity of the Marcellus Shale gas play could serve Pennsylvania’s energy needs as well as making the Commonwealth a major supplier of natural gas to the heavily populated East Coast.
A Boon for Pennsylvania
If the Marcellus Shale gas play lives up to the experts’ estimates, the Commonwealth of Pennsylvania could become a significant exporter of energy. Natural gas producers are currently obtaining the gas and mineral rights from property owners who are interested in leasing their land for gas exploration.
It has been reported that in January 2008 gas leases were being signed for approximately $100 per acre. By May the price had jumped to $2,000 per acre. In 2008, 195 Marcellus Shale wells had been drilled and according to The Pennsylvania Department of Environmental Protection another 768 were drilled in 2009. In 2010, DEP granted 1,985 new drilling permits. In 2008, the Marcellus Shale Coalition was formed, which is an organization dedicated to developing the Marcellus Shale gas play. Numerous companies from gas explorers to drillers comprise the coalition. In opposition, environmental groups have also mobilized.
Not Without Risk
The drilling is not without risk. In June of 2010 a well in Clearfield County blew out, sending untreated frac water and natural gas into the environment. The event raised many concerns, among which was how closely wells should be situated to populated areas. Fortunately, this happened in a rural area and no one was harmed.
The Pittsburgh area is at the beginning of what could be a natural gas boom, bringing plentiful, clean-burning energy to the market. The energy would provide economic prosperity, revenue to tax coffers, and lucrative jobs, not to mention increased income to those leasing the land. However, concerns about the environment and how to regulate the industry need to be resolved. If those issues can be addressed, Pennsylvania and the nation stand to benefit by the bountiful resources yielded by mud that was laid down millions of years ago.
By Jan Palko