Gas Drilling in the Marcellus Shale - FAQs
1. What is Marcellus Shale?
Named for the village of Marcellus in upstate New York, the Marcellus formation is black shale located deep underground. It extends throughout the Appalachian Basin from New York to Tennessee. The Marcellus Shale is part of a thick sequence of layered rocks in New York that are generally tilted to the south. Therefore, although the Marcellus Shale is exposed at the ground surface in some locations in the northern Finger Lakes area, it is as deep as 7,000 feet or more below the ground surface along the Pennsylvania border in the Delaware River valley.
Geologists estimate that the shale contains between 168 trillion to 516 trillion cubic feet of natural gas throughout its entire extent. New York State uses about 1.1 trillion cubic feet of natural gas each year. Approximately 5 percent of this amount is currently produced in New York State. It is not known how much gas will be economically recoverable from the Marcellus in New York.
2. The natural gas has been here for years, why the interest now?
Previously, the depth and tightness of the rock made gas exploration and development very expensive. Within the past few years, two technologies, horizontal drilling and hydraulic fracturing, were tested in the Marcellus formation in northeastern Pennsylvania resulting in economic production. With the Marcellus so close to the high natural gas demand markets of New York, New Jersey and New England, and the Millennium Pipeline currently under construction through the Southern Tier, these technological developments triggered an intense interest in drilling and leasing in the Marcellus Shale.
3. What is horizontal drilling?
Diagram of horizontal drilling and hydrofracing.
(Image: Brad Cole, Geology.com)
Horizontal drilling involves drilling down and then horizontally (see diagram). Routinely used for almost 30 years, it allows a maximum penetration into rock to recover gas. A significant benefit is that natural gas wells can be drilled in several directions from the same surface location, disturbing only a few acres above ground. In 2007, approximately 10 percent of drilling permit applications received by the New York Department of Environmental Conservation were for horizontal or directional wells.
4. What is hydraulic fracturing?
Hydraulic fracturing is a technique that forces fluid into a well to break or "fracture" the shale so that the gas trapped within the rock can be released. High pressure fractures the rock and pushes the fractures open. Sand particles are injected to "hold" the cracks open so gas can flow back to the drill bore. This technique greatly increases the amount of gas that can be recovered.
Hydraulic fracturing is required where rocks are relatively tight. In other words, the rock does not allow water, oil or gas to pass through it. Today, there are thousands of oil and gas wells in New York State that have been hydraulically fractured, and a number of these are horizontal or directional wells.
5. How is the hydraulic fracturing in Marcellus Shale different than other hydraulic fracturing?
The proposed Marcellus Shale drilling and hydraulic fracturing operations will require a larger volume of water to break the rocks in order to produce the desired amount of gas. Each well may use more than one million gallons of water.
6. How will water resources and public water supplies be protected?
The Susquehanna River Basin Commission and the Delaware River Basin Commission regulate the rate and volume of water withdrawals within their respective basins. These regional water authorities must review and approve certain water withdrawals, including water used for hydraulic fracturing and drilling projects in the Marcellus Shale.
Municipal water wells are protected by the requirement for a full environmental assessment if a proposed oil or gas well is within 2,000 feet of the municipal well and a supplemental environmental impact statement (EIS) if within 1,000 feet. All groundwater, including private wells, are protected by strict construction requirements for oil and gas wells.
No known instances of groundwater contamination have occurred from previous horizontal drilling or hydraulic fracturing projects in New York State.
7. What happens to the water and hydraulic fracturing fluid after the drilling process?
Fluid removed from the well is required by law to be handled and disposed of properly. It must be transported by a hauler with a valid New York State Part 364 Waste Transporter Permit. The permitted hauler is responsible for ensuring that the waste is delivered to an authorized waste receiving facility and that each shipment conforms to the operating requirements of that facility; and for maintaining records of the amount of waste transported to each receiving facility.
8. What is in the fracturing fluids?
Typically, fracturing fluid contains corrosion inhibitors, anti-bacterial agents and other additives that allow the fracturing process to work more effectively. The New York State Department of Environmental Conservation (NYSDEC) is assessing the chemical makeup of these additives and will ensure that all safeguards and best practices are followed.
9. What is NYSDEC's role in private gas leasing?
NYSDEC sets specific parameters for all drilling and hydraulic fracturing operations in the State. This ensures that well drilling and hydraulic fracturing are conducted in an environmentally sound manner.
NYSDEC does not regulate leases on private lands. NYSDEC does encourage landowners to know their rights when dealing with gas exploration companies. See: Landowner's Guide to Oil and Gas Leasing .
