What is Marcellus Shale?

The Marcellus Formation (also classified as the Marcellus Subgroup of the Hamilton Group, Marcellus Member of the Romney Formation, or simply the Marcellus Shale) is a unit of marine sedimentary rock found in eastern North America. Named for a distinctive outcrop near the village of Marcellus, New York in the United States it extends throughout much of the Appalachian Basin. It was formed by the accumulation of sediment into a sea and eventually buried over many thousands of years and compressed to produce an organic-rich black shale. The shale contains largely untapped natural gas reserves, and its proximity to the high-demand markets along the East Coast of the United States makes it an attractive target for energy development.

Stratigraphically, the Marcellus is the lowest unit of the Devonian age Hamilton Group, and is divided into several sub-units. Although black shale is the dominant lithology, it also contains lighter shales and interbedded limestone layers due to sea level variation during its deposition almost 400 million years ago. The black shale was deposited in relatively deep water devoid of oxygen, and is only sparsely fossiliferous. Most fossils are contained in the limestone members, and the fossil record in these layers provides important paleontologal insights on faunal turnovers.


The black shales also contain iron ore that was used in the early economic development of the region, and uranium and pyrite which are environmental hazards. The fissile shales are also easily eroded, presenting additional civil and environmental engineering challenges.

Although it has long been identified as potentially rich in fossil fuels, it isn’t until recently that Marcellus is being explored as a solution to energy problems. Since the success of the Barnett Shale play in North Central Texas, companies have been able to transfer the hydrofracturing technology to other areas, such as the Fayetteville Shale play (Arkansas), Haynesville Shale play (Louisiana and Eastern Texas), and the Marcellus Shale play. The close proximity of the cities to the Marcellus Shale and their high demand for natural gas means that the transportation costs normally associated with natural gas would be significantly lower, making it economically feasible for the region.

Extracting natural gas from the Marcellus Shale formation requires both vertical and horizontal drilling, combined with a process known as ‘hydraulic fracturing.’ After the well is drilled, cased and cemented to protect groundwater and the escape of natural gas and other fluids, drillers pump large amounts of water mixed with sand and other fluids into the shale formation under high pressure to fracture the shale around the well, which allows the natural gas to flow freely to the well bore. The amount of water typically required for hydraulic fracturing ranges from about one million gallons for a vertical well to approximately five million gallons for a vertical well with a horizontal lateral.
Once the hydraulic fracturing process is completed, the used water, often referred to as “frac returns” must be reused in the next well or sent to an approved treatment facility.

In 2003, the Pennsylvania Marcellus shale play began when Range Resources – Appalachia, LLC (previously known as Great Lakes Energy Partners, LLC) drilled a well into the Lower Silurian Rochester Shale in Washington County, PA. Because the Marcellus Shale showed promise, Range drilled additional wells while experimenting with drilling and hydraulic fracturing techniques similar to those used in the Mississippian Barnett Shale gas play in Texas. They first produced the Marcellus gas in 2005 and have since permitted over 150 wells in Washington County.

What does the future hold for Marcellus Shale? According to the “The Pennsylvania Marcellus Natural Gas Industry: Status, Economic Impact, and Future Potential.” a study conducted by researchers at Pennsylvania State University and commissioned by the Marcellus Shale Coalition, the Pennsylvania Marcellus could produce approximately one quarter of the America’s natural gas by the year 2020.

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Ethane Cracker Plant

Shell recently announced that they will be building a $6 billion ethane cracker plant near Pittsburgh. This plant will boost employment, economic development, and commercial real estate, while encouraging more shale drilling throughout the region.


The upcoming construction of the new multi-billion dollar Shell ethane cracker plant in Beaver County, PA, means that there are unlimited opportunities for everyone who is involved in any aspect of regional business development. Marcellus Utica Connection is seeking strategic partners to launch marketing initiatives and connect the different industries that will most benefit during this time of unprecedented growth.