The Marcellus Shale Formation Information Site


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The Marcellus Shale Formation is the largest source of domestic natural gas yet discovered in the United States. Here are some facts, maps and figures about this incredible resource beneath U.S. soil.

What Is The Marcellus Shale Formation?

Named for the town of Marcellus New York, where the shale reaches the surface, it is a Devonian age (roughly 390 million years old) member of a geological structure known as the Hamilton group. It formed when Devonian age seas, as seen in the illustrations below, covered much of North America.

Image from Wikipedia

Above: An artist's conception of what a Devonian age sea might have looked like. The Marcellus shale was formed as sediment was deposited on the bottom of such seas.

Of the Hamilton group formations, the Marcellus shale is the deepest and therefore oldest member of the group. It is mildly radioactive since it contains a small amount of uranium and produces gamma radiation from decaying organic matter. No significant amount of this radioactivity is released in the natural gas produced from the shale.

marcellus black shale rock

Natural gas is the reason for all of the excitement surrounding the Marcellus shale.  Over millions of years the mud that eventually became the Marcellus shale was deposited on the deep, oxygen deprived seafloor. It contained marine organic matter including algae, and other organisms in great abundance. Due to the lack of oxygen this organic matter was slow to decompose. Eventually more sediment covered it and this rich muck became covered yet again by layers of more sediment that was rich in the exoskeletons of marine organisms (calcium carbonate) which later became limestone.

The Marcellus formation, over much of it's extent, is trapped between the Onondoga limestone underneath the shale, and capped by the Tully limestone on top. These impervious layers  of limestone have trapped a great quantity of natural gas inside the shale. The natural gas is a result of thermal (thermogenic) and biological (biogenic) origin. It is trapped in the fissures, cracks and pores of the shale in great abundance. The problem up until recently was been how to get this natural gas out of the tight, non porous shale so that it can be used.

The geological formation known as the Marcellus shale was known about for decades but only recently was the technology available to extract natural gas from shale.

While the geological aspect of the formation is fascinating, the primary focus of this site will be to explore the natural gas producing potential of this vast shale formation and the impact of this discovery on the region in which it is located and the U.S economy.

Thickness Of The Marcellus Shale

Shale thickness runs from 900 feet beneath New Jersey to around 40 feet across the border in Canada. In West Virginia, where much new drilling activity is located the thickness is in the 200 foot range.

Map Of The Marcellus Shale Formation Showing Bed Thickness

Gas Content Of The Marcellus Formation

There may be as much as 4,359 trillion cubic feet of natural gas trapped in the formation according to University of Pennsylvania geologist Terry Engelder. Of that approximately thirty percent may be recoverable. This alone could supply the natural gas needs of the United States for twenty years or more.

The Game Changer, Horizontal Drilling

Up until about fifteen years ago most oil and gas wells were drilled as vertical holes down through rock formations like the Marcellus. This technology worked fine for highly porous reservoirs made up of sandstone or fractured limestone. A vertical gas or oil well could drain an area of about ten to forty acres, on average, over a period of time. Shale however is a dense rock which does not give up much fluid or gas from a vertical hole drilled through it. The Marcellus shale can be over 900 feet thick in some areas but even this is not enough profile of the shale to release a significant amount of gas. What horizontal drilling accomplishes is a hole drilled up to several thousand feet horizontally across the shale. After horizontal drilling has been done a hydraulic fracturing job or frac job is done on the newly drilled well. Because the technology is new and non typical, gas from shale formations is referred to as "unconventional natural gas".

In the Barnett shale, near Fort Worth Texas, oil and gas companies began to perfect the technology of horizontal or directional drilling in the late 1980's. As the technology evolved tools such as directional mud motors and LWD or "logging while drilling" equipment which allows for the navigation of directional drilling assemblies, became more reliable and affordable. Now horizontal drilling is being used in shale formations across the United States. This unconventional gas revolution has made natural gas one of the most affordable forms of energy and will no doubt be a part of the solution to reducing foreign oil imports.

What Is Hydraulic Fracturing?

The second key to the development of the Marcellus shale formation is a technology called hydraulic fracturing. After casing or heavy pipe has been run into the newly drilled hole to line it, extremely high pressure pumps are hooked up and fluids (mostly water and sand) are forced down into the shale to open cracks and fissures so more natural gas can flow out of the formation. Hydraulic fracturing is the primary completion process used in the Marcellus. It has been the subject of controversy lately, with environmental groups protesting the drilling of new wells in the environmentally sensitive Chesapeake Bay watershed among other areas.

Wells in the Marcellus formation are as deep as 9000 ft and the productive zone is far below any water aquifers. A properly cased gas well, lined with thick steel pipe and cemented into place, will ensure a safe frac job. State and federal agencies monitor the process of casing and testing new wells and hydraulic fracturing. The source of contention among environmental groups is the number of chemicals pumped into the formation along with frac water and sand. Up to fifty percent of this fluid may remain in the ground however it may take millions of years for any of it to migrate upward to water bearing zones. If proper safety measures are undertaken hydraulic fracturing can be a safe means of producing Marcellus shale gas wells. For a video of a Marcellus shale frac job see: Marcellus Videos



A Major New Source Of Natural Gas

One reason the Marcellus shale is such an important resource is the proximity of the productive area to major metropolitan areas and factories that use natural gas. In the past, natural gas had to be piped through transcontinental pipelines from as far away as Texas. A number of similar shale gas reserves have been discovered in the United States, turning natural gas into a local commodity for many regions. Large cross country pipelines are not cheap to build or maintain. They require expensive real estate, regular maintenance and inspection using aerial  and ground surveillance and expensive corrosion protection equipment. Large compressor stations must be located every few miles to boost the pressure. All of this means that gas from the Gulf of Mexico and southern states costs more.  Because natural gas from the Marcellus is located nearer to the point of consumption, it can be sold at a cheaper yet more profitable price since transportation costs are lower.

 See the map below which shows the network of natural gas pipelines. The Marcellus shale is located in the terminus of many of these pipelines. Existing pipelines can carry natural gas from the region to other parts of the United States as other gas producing areas decline.

Map of major natural gas pipelines in the United States

Current Drilling Situation In The Marcellus Shale

Currently most of the horizontal drilling activity is located in West Virginia, Pennsylvania north east toward New York. The "fairway" as it has been described by Penn State geoscientist Dr. Terry Engelder, runs roughly through the center of Pennsylvania and into southeastern New York. The thickest parts of the Marcellus Shale are of the highest interest to oil and gas companies because there is a higher quantity of shale and also because there is a higher amount of Total Organic Carbon (TOC) in the shale. Higher total organic carbon can translate to more gas trapped in the shale.

Marcellus shale fairway showing hottest drilling activity for natural gas Blue areas indicate best gas potential.

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A Bonanza To Landowners

According to the Northeast Pennsylvania newspaper the Times Leader lease payments to landowners continue to skyrocket. "In January 2008 leases were being signed for values near $100 per acre. By May that value had increased to over $2000 per acre." In the Barnett shale near Dallas, some landowners have been paid as much as $18,000 an acre. We could see similar payments in the most productive parts of the Marcellus shale. One thing is certain, all of this cash will have a positive and lasting effect on the region. It will create thousands of new high paying jobs and provide tax revenue to for state and municipal governments to use in road and school construction among other things. As we have seen in other resource rich states such as Texas, oil and gas revenue can reduce the tax burden on individuals and bolster the economy.

Marcellus Shale Lease Payment Checks Being Sent Out

According to a story by the Patriot News dated Sept 27, 2009, a flood of checks has begun to make their way into the hands of landowners. Quite a few of these first lease payment checks total over $100,000. After the large lease payment checks will come monthly royalty checks for the gas produced. Wells in the Marcellus shale could be productive for decades, meaning a long stream of needed income to the region. Land owners have begun to form groups to negotiate with oil and gas companies in the Marcellus shale. One such group of over 700 landowners met with Chesapeake in Black Walnut PA and received checks for $5,750 an acre on over 37,000 acres. Pennsylvania governor Ed Rendell expects to receive over 37 million dollars from leases on state forest lands.

Video Of Marcellus Shale Outlook Featuring Dr. Terry Engelder (21 minutes)


 See More Marcellus Shale Videos Here

The relatively poor state of West Virginia has seen a dramatic increase in the number of wells recently. Chesapeake Energy has 17 rigs drilling in the area, as of Sept, 2009, and plans to double that number by 2011. According to the Baker Hughes rig count for October, 2009 there were 21 rigs drilling in West Virginia and 56 in Pennsylvania, in spite of very low natural gas prices. As natural gas prices begin to rise, due to cold winter temperatures and an increase in industrial demand, the rig count is sure to rise.

The major players in the Marcellus shale include Chesapeake, Range Resources, EXCO Resources, Anadarko, XTO, Rex Energy, Cabot Oil and Gas, EOG and others.

Author: Nolan Hart

For a map of the major shale gas formations in the United States see United States Shale Gas Basins



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