Introduction to

As we look at gas drilling projects around the Marcellus Shale it is important to understand a few of the basics.

The Marcellus name
  The origin of its name:

Marcellus Shale is named for a distinctive shale outcropping near the village of Marcellus, New York, just west of Syracuse.

Halliburton hydraulic fracturing
Halliburton fracking Marcellus Shale wells

Types of wells
  There are two types of gas wells on Marcellus Shale, horizontal and vertical.

Horizontal wells, which are first drilled down then gradually curved and drilled horizontally, require much more water for well completion than vertical wells. Water requirements in early Marcellus gas wells averaged 4 million gallons per well, with approximately 1 million gallons returning to the surface as flowback or produced water.

Vertical wells, the type of gas wells traditionally drilled in the past, are drilled straight down without any laterals extending horizontally. Water requirements are much less, often under 10% of the water required for a horizontal well. Gas production is usually less as well.


West Virginia drilling pad
West Virginia well site and pipeline work

Locations of natural gas
The next distinction is what type of natural gas is being exploited, Marcellus shale gas or coal bed methane (CBM), since both types of wells exist around Marcellus Shale country.

Marcellus Shale gas wells are typically 6,000 to 7,000 feet deep with laterals extending another 3,000 to 4,000 feet, with some horizontal bores extending 10,000 feet. Early drilling pads often contained 8 wells per pad while newer pads may have as many as two dozen wells.

Coal Bed Methane (CBM) wells reduce the amount of explosive gas present around coal seams prior to mining activities. Depths are usually in the hundreds of feet instead of the thousands of feet, as typically seen with Marcellus wells.

Drilling pads and frac pits
Multiple pads and frac pits in SW Pennsylvania

Types of natural gas
There are two types of natural gas, wet gas and dry gas.

Wet gas doesn't mean "wet" with water, even though some water comes up with the gas. "Wet" means the mix of hydrocarbons that contain a considerable amount of condensable or liquid compounds, like propane and butane, that are heavier than ethane. Gas processing companies earn extra revenues from the compounds extracted from wet gas, which is typically found on the western edges of the Marcellus Shale formation.

Dry gas is more 'pipeline ready' since it doesn't contain all the liquids that need to be extracted before pipeline shipment.



Generation of natural gas depends on heat-induced chemical reactions that convert lipids to kerogen to petroleum and then to natural gas. The interior of the Earth is hot relative to its surface with the interior temperature increasing (a geothermal gradient) at the rate of about 57°F/mi.

Kerogen is converted to petroleum at a temperature of about 32°F which means that the Marcellus had to reach a depth of about 1.86 miles (mi) before any natural gas was produced. The Marcellus was ultimately buried as much as 2 to 4.5 mi depending on its location relative to the Acadia Mountains to the southeast.

Burial was deepest to the east in the area of the anthracite coal district of Pennsylvania. Erosion and exhumation during the past 200 Ma have placed the Marcellus at its present depth of burial, somewhat shy of 1.86 mi at its maximum in Washington County.

Governor’s Marcellus Shale Advisory Commission, Commonwealth of Pennsylvania


Natural gas money
Gas lease payments and royalty amounts have been all over the board during the first five years of Marcellus leasing.

Leasing acreage
Some acreage has been leased for as little as $5 per acre, while other leases are for $5,000 per acre or more. Many early Marcellus leases were signed for very low acreage amounts. Lease amounts have often fluctuated with the current market price of natural gas. Talking points should be addressed early that include gas pipeline right of ways.

Royalty agreements
Percentages have traditionally run the spectrum from 12.5% (Pa. minimum) to 20% or more.  Landowners usually do best when they are patient and form a group to negotiate the best acreage lease amounts and percentages. Some Marcellus gas companies deduct fees from royalty payments for drying, transportation and storage of the gas. Wording should be added to standard leases to 'cover all the bases.'

Gas lease term
Just because a property owner signs a 5-year lease doesn't mean it will only be 5-years long. A drilling company can move a piece of excavation equipment onto leased property the last day of the lease, and the lease will be extended since the land is "held by production."

What is covered in a lease
Unless specified, the lease may contain rights to gas and mineral rights other than just Marcellus Shale. For example, it might also include the rights to the Oriskany, Utica or Trenton Black River formation. You may be granting permission for an impoundment or temporary pipeline to be placed on your property, so study the fine print. Leases should be fine-tuned by a knowledgeable professional to address these various details and prevent unpleasant surprises.

Impoundment dam and gas well pad
Today's fracking creates "super" pads and impoundments

Water wells
Well owners are advised to get complete "baseline" tests of their well water done prior to the start of any gas drilling activities nearby. If well water quality is adversely affected by gas drilling within a certain radius (1,000 feet in Pa. in 2010) legal claims must be made within a set time period. This time period may be six months or less, so time is of the essence.

Gas well traffic
Once there are gas wells on a property, there will be continuous and ongoing traffic to and from these well sites by well tenders, vacuum trucks and maintenance crews. Many landowners are relieved that they forced drilling companies to move their access roads further away from their houses than originally planned, due to the incessant traffic.

Gas pipeline near a home

Pipelines & Compressor Stations
Pipeline right-of-ways are cleared of trees for the pipelines needed to gather and move natural gas off site. Once these gas lines areas are cleared, trees can never be planted on them again, since it would risk damage to the pipeline. Compressor Stations are built along pipelines to move the gas through pipelines. There are often issues of noise, light and odors around these compressor stations, as well as health issues due to poor air quality.

Heavy truck traffic
The heavy flow of truck traffic catches many communities by surprise. Traffic is heaviest during the preparation, drilling and completion of Marcellus Wells. Municipalities are well advised to adequately bond their roads to cover road repairs that will be necessary due to thousands of heavy truck trips. Bridges should be inspected to ensure they have proper weight ratings, and later patrolled to enforce these weight limits, as heavy truck traffic increases.

April 2011

Pennsylvania DEP permits issued Jan-March 2011: 1,510

Pennsylvania Marcellus wells drilled as Jan 1- March 10, 2011: 301 (as compared to only 152 "other" wells)

What are the trends in Pennsylvania's Marcellus wells?
2008 - 196 wells
2009 - 763 wells
2010 - 1,386 wells
2011 - 1,592 wells (projected from current rate)

Marcellus vs Conventional wells in Pennsylvania: 
2009 - 1 : 2.3
2010 - 1 : 1
2011 - 2 : 1 (projected)

Orphan wells: DEP estimates 325,000 oil and gas wells in PA; has records for only about 140,500. Of the latter, the DEP knows the owners of only 88,300. That means that ~236,700 (let's just say a quarter of a million) wells are wards of the state (184,500 whose whereabouts are unknown).


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