Natural Gas Drilling Overview
What is the Marcellus Shale?
The Marcellus Shale is a layer of deep sedimentary rock, deposited by an ancient river delta, with the remains of it now forming the Catskill Mountains. The Marcellus Shale extends deep underground from Ohio and West Virginia northeast into Pennsylvania and southern New York., including the Catskills and the West-of-Hudson portion of the New York City Watershed. New York’s portion of the Marcellus Shale is approximately 18,750 square miles and is very deep – over 1 mile below ground.
What is Hydraulic Fracturing?
Hydraulic fracturing, or hydrofracking, is the
creation of fractures within a reservoir that contains oil or natural gas to
increase flow and maximize production. A hydraulic fracture is formed when a
fluid is pumped down the well at pressures that exceed the rock strength,
causing open fractures to form in the rock.Hydraulic fracturing allows drilling
companies to extract natural gas from shale reserves such as the Marcellus.
Natural gas is trapped within fractures between the grains of this fine-grained
rock. Staged from a massive platform (towering hundreds of feet above ground),
drillers drill down vertically into the shale, turn 90 degrees to drill
horizontally (sometimes over a mile in length), and
then inject water, sand and chemicals under high pressure to release the gas. The pressurized water forms fractures in the rock, which sand and chemicals then prop open.
What are some of the Environmental Impacts?
There are many environmental impacts associated with hydraulic fracturing, or “hydrofracking.”
Among them are, water consumption, wastewater disposal, use of toxic chemicals, substantial truck traffic, air pollution, noise from the loud, twenty-four hour hydrofracking operations, potential groundwater and well water contamination, deforestation, roadbuilding and surface water runoff from these large industrial sites. The cumulative effect of these impacts may indeed transform entire communities – turning previously rural, agrarian areas into “fractured communities.”
Hydraulic fracturing requires up to 3 to 8 million gallons of water per hydrofrack, and typically each well is hydrofracked many times. The water must be trucked in (involving millions of truck trips), stored on-site, and the wastewater disposed of properly (nearly all of the fracking fluid injected returns to the surface, bringing with it materials from underground including brines, heavy metals, radionuclides, and organics). Even though the gas industry claims that toxic chemicals represent less than 1% of hydrofrack fluid, the U.S. Geological Survey explains that a typical 3 million gallon hydrofrack produces 15,000 gallons of chemical waste. In existing Marcellus wells outside of New York this waste is stored on-site in large holding ponds until trucks haul it away. Disposal of wastewater is a problem – there are no disposal sites.