The Marcellus shale formation is a widespread layer of gas bearing shale that was deposited millions of years ago the Devonian age in vast protected seas that once covered North America. Microscopic marine life that once lived in those seas decayed and formed oil and gas under heat and pressure. Subsequent rock layers were deposited on top of the Marcellus shale, trapping the hydrocarbons inside.

The Marcellus formation is located in the Appalachian Basin and  stretches from New York through Pennsylvania, Ohio, Maryland and West Virginia. It also extends under the Great Lakes, across into Canada in  the province of Ontario. Until recently it had been overlooked since a vertical gas well drilled down through the shale would not give off enough gas to be economically feasible.

Now with horizontal drilling techniques, oil and gas companies can drill sideways across it and expose more surface area for gas to seep out. These methods were unavailable up until recently. New horizontal drilling techniques include LWD or logging while drilling equipment which can log the formation in real time to tell what kind of rock the drill bit is passing through.  A gamma ray sensor indicates if the drill bit has passed down into unproductive beds of limestone or sandstone on non gas bearing shale. Shale gives off more gamma rays than most rocks as it decays, and shows up as a high API count reading on the LWD derived well log. This enables the company geologist to help the directional driller stay within the Marcellus shale.  Below is an illustration of a typical gamma log. The higher API Gamma counts likely indicate shale. A lower count indicates sandstone or limestone.

This information is sent uphole as a series of pulses in real time, allowing the driller to keep the drill bit in the shale formation where the gas is, even if the bed of rock is thin. This allows companies to exploit relatively thin bed areas of the Marcellus that would otherwise not be productive without accurate LWD enhanced horizontal drilling techniques.

As of 2008 only a few water  fractured  horizontal wells were actually tapping the Marcellus formation. It is reported that at least one is currently producing more than 3 million cubic feet of natural gas daily.  Although this rich resource has been know about for a long while, only until recently has it begun to be explored and exploited. 

Why Is The Marcellus Formation Important?

The United States went from being the worlds biggest producer of oil to it's biggest importer from 1970 to 1990. Oil imports are rising and there is no clear plan to wean us off of oil. Natural gas has been proposed as an alternative to oil. Gas to Liquids or GTL technology is able to make clean burning gasoline and diesel from natural gas. Compressed natural gas is already in use as a motor fuel. With more shale gas reserves being discovered, including the  Eagle Ford Shale in Texas, there is enough natural gas to last for dozens of years at current usage rates. Shale gas reserves like the Marcellus formation may hold the key to energy independence in the United States. Also, since natural gas is clean burning, it produces less green house gas than coal with no acid rain.

Currently there are scores  of  "land men" right now out scouring the countryside to buy up mineral rights from landowners as the boom is now on. If you are one of those fortunate to own land in the area,  consult with an attorney before signing an oil and gas lease!   

 In 2007  professors  Engelder and  Lash,  wrote a report that the Marcellus could hold 167 trillion cubic feet of  natural gas. That report was based on very conservative estimates. Their own higher estimates suggest the Marcellus shale  could hold as much as 500 trillion cubic feet of total gas and assuming a ten percent recovery factor, that mean almost 20 trillion cubic feet of marketable natural gas. It's like our own north slope of gas that has been sleeping right under our feet.     

In a region of the  United States that has seen its share of economic booms and busts the impact of the Marcellus Formation will undoubtedly be remarkable. In a similar gas bearing shale formation, the Barnett Shale of North Texas it was estimated by the Greater Ft. Worth Chamber Of Commerce that the impact of the development of that gas bearing formation has been equal to the building and operation of five Boeing aircraft plants.

In an area with very little in the way of oilfield infrastructure whole new industries will have to be grown from the ground up. From oilfield liquids transport, well location building, pipelines and compressor stations to the vast support network of service companies that keep the oilfield up and running.

Already directional drilling and mudlogging companies are opening up satellite offices in the areas of the Marcellus Formation.

As new wells are brought on line there will be a need for production employees to keep the wells up and running and maintain equipment. However the biggest economic impact will come during the drilling phase where the most up front money is spent. As production comes on line the tax coffers of local municipalities and the state will be boosted, meaning billions of dollars over the coming years for education, roads, and social programs.

Residents will eventually see lower utility bills as cheaper gas is purchased locally for power generation and home distribution.

The estimated size of the Marcellus Formation is up to ten times larger than the Barnett Shale and is destined to have a far greater economic impact and implications on our energy future. Wit up to 500 trillion cubic feet of natural gas reserves the Marcellus Formation could indeed go a long way to helping the U.S. cure its addiction to foreign oil.

Why the Marcellus Formation is not a major news story is a mystery to the author but we will surely hear more about it in the coming months.

Environmental Impact Of Drilling In The Marcellus Shale

photo from the Maryland Geological Survey

The "Christmas Tree" above is what remains on surface after a Marcellus shale well has been drilled. The impact to the well site is about the same as building a home. In some cases a tank or group of tanks may be located at the site of the wellhead. In other cases gas produced by the well will be piped to a central tank battery. There is little impact to the environment and no oil spills, etc, to contend with. When Marcellus shale wells are drilled a large quantity of water is needed for a "frac job". Hydraulic fracturing is used to break apart the shale formation and create billions of tiny cracks for the gas to escape from. Once thousands of gallons of water have been pumped into the Marcellus formation it must be flowed back and disposed of. Flowback water must be treated to remove hydrocarbons such as distillate, similar to gasoline. This requires sophisticated equipment. Having enough fresh water available and treating it to be returned to the environment could be a challenge to the development of the Marcellus Shale.