What is Hydraulic Fracturing or "Fracking"?

 

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Fracking

Fracking is not a good thing if we're trying to reduce global warming causes and impacts. I provide a background on hydraulic fracturing and environmental impacts.

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 Hydraulic fracturing is the process of creating fractures in rock with the purpose of releasing a fluid under pressure. This "fluid" is usually gas or petroleum as far as the fossil fuel industry is concerned. These fractures also occur naturally as in the case of "veins" or "dikes", where magma from deep within the earth flowed towards the surface.

Oil and gas companies create their own fracturing of a rock layer with the sole purpose of extracting fuel. A bore hole is drilled into the geologic formation which contains the oil/gas. Then a highly pressurized fracking fluid is pumped into the hole leading to new channels in the rock and hence, allows for extraction of fossil fuels.

As the fluid is injected down the hole and the fracture opens, other materials are sometimes added to prevent the fractures from closing - especially when the injection processed has ended.

Not all wells are the same; some are very permeable whereas others are low volume wells, depending on the type of rock and geologic structures. And example might be shale for low permeability and sandstone for high permeability; the former uses 20,000 to 80,000 gallons of fluid while the latter can use up to 2-3 million gallons of fluid per well. There can be environmental issues in the disposal of this fluid.

Examples in Nature

"Veins" can be caused by seismic activity which leads to variations in stress levels of the rock. Differing volumes of fluids can be pumped into fractures during earthquakes. The fluids (usually containing minerals) can create a vein when pushed up through rock and then can harden and crystallize; sometimes a rock will appear one color and there will be a stripe of some other material in the rock.

The formation of a "dike" is similar to that of a vein. The difference is that the fluid filled cracks are molten rock, or magma. Sometimes in sedimentary rock with a lot of water content steam will be found at the leading edge of the magma. Obviously this feature would be more common in active geologic regions such as areas near the boundaries of the continental plates or along the "ring of fire".

Fracking to Release Fossil Fuels

As mentioned earlier "fracking" or "hydraulic fracturing" is using pressurized fluid to expand cracks in rock to release oil or gas from underground reservoirs. These reservoirs are typically found in porous sandstones, limestones, or dolomite rocks. Sometimes the deposit can be found in shale or coal beds. The oil/gas formations can be retrieved from as deep as 1.5 - 6.1 km (5,000-20,000 feet). Sometimes the formation just needs to be tapped and the pressure alone will allow it to shoot to the surface. Other times a conduit needs to be formed to draw the fossil fuels to the surface.

The fracture is created when pumping the fracking fluid at sufficient rates to exceed the fracture gradient of the rock. As the fracture grows, permeable material (like sand) is added to the hole to stabilize the well. The fuel can then be drawn upwards through the porous material.

Most hydraulic fracturing is performed in vertical wells. But the latest technology allows for horizontal wells also. The lateral drill hole can extend up to nearly 3 km (2 mi) in some cases. Vertical wells usually are only 15-90 meters (50-300 ft) deep. Hydraulic fracturing is employed by 90% of natural gas wells in the United States.

The fracturing fluid is a combination of water, chemical additives, and proppants (granular substances such as pellets or sand that help the fluid do its work). In addition there are sometimes gels, foams and compressed gases (i.e., nitrogen or carbon dioxide) added to the mixture. In addition to the fluids and equipment to propel the fluid, there is transportation and storage of the fluid and the resulting fuel.

The Marcellus Shale formation is one of the latest targets for fracking. This formation extending from West Virginia and Ohio eastward through Pennsylvania into New York State has had its share of news worthy stories, from estimated economic impacts and jobs, to taxation, to environmental concerns.

Environmental Concerns

There are plenty of environmental concerns when it comes to hydraulic fracturing, from contamination of ground water, pollution of the air and global warming impacts, to spills and mishandling of waste in the well location and health effects.

While the EPA has been aware of some possible contamination issues, there was doubt among officials (from testimony at Senate Hearing Committees) that the fracking process itself has affected ground water. The EPA studies were criticized for being too narrow in scope, such as concerns about water quality contaminated from transporting fracking fluids, some fish kills and even documented acid burns. Private well owners have complained about contamination. In 2005 hydraulic fracturing was exempted by the U.S. Congress from any regulation under the Safe Drinking Water Act!

The reports of contamination of water began to increase as fracking heated up. One amazing example took place in the town of Dimrock, PA with a report of 13 private wells found to be contaminated with methane. And one of them actually blew up. The local gas company was ordered to compensate the homeowners although they continued to deny responsibility. There have even been reports of radiation in fracking fluids that were released into nearby rivers.

Beyond ground water and possible surface pollution, there are the emissions of greenhouse gases which are the leading causes of global warming and air pollution at the surface. The emissions from the natural gas development and production include particulates, nitrogen oxides, sulfur oxide, carbon dioxide, and carbon monoxide. Other emissions linked to development include methane, ethane and volatile organic compounds (VOCs). The VOCs have been implicated in causing a range of health issues - from respiratory illness to neurological problems, birth defects and cancer.

Although natural gas burns cleaner than oil or coal and it is supposed to help lessen global warming, an amount of methane is typically released by these wells. And the methane over short time periods is actually worse than coal or oil due to how potent this greenhouse gas is (20-25 times more potent than CO2). The methane gradually breaks down and has a lifetime in the atmosphere of around 8-9 years (CO2 lasts around 100 years). So even if natural gas is burned efficiently, its carbon footprint is still worse than coal or oil for timescales less than 50 years.


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