Hydraulic fracturing, often abbreviated fracking, is the excavation process of creating a fracture in a layer of rock, by use of highly pressurized fluid, in order to extract deposits of petroleum or natural gas. Fracking began as subsidiary method to mining coal, and evolved as a easier and cleaner way to extract natural gas deposits underground. Before fracking, the mining method for withdrawing buried gas was inefficient and expensive. The process begins with a wellbore* being drilled into rock formations where potential deposits may lay. A mixture of pressurized fluid is then injection through the wellbore, which creates new fracture channels within the rock. These new channels are then plugged and the gas deposits are then extracted through wells.

The fluid injected into the rock layer is usually a heterogeneous solution of water, proppants and various chemical additives. In some cases crews add additional solvents such as gel, foams, or compressed gas such as nitrogen and carbon dioxide. The mixture of the solution is constituted by the permeability of the rock. Harder rocks require stronger solutions. Chemical additives are applied to specific rock layers to improve operations and efficiency. The fracturing solution, in most instances, is 99 percent water with less than 1 percent chemical additives. This solution may change over the elapsed time of the operation as well. As excavation enters deeper layers of rock, it may require more or less power to continue.

Hydraulic fracturing equipment used to unearth natural gas consists of various types of pressured pumps, treatment pumps, chemical additive units and monitoring unit. The fracturing equipment operates over wide range of pressures and injection rates, and can reach up to 100 MPa (15,000 psi) and 265 L/s (100 barrels per minute).

Hydraulic fracking remains controversial due to the possibility of the fracking processes contaminating drinking water reservoirs. In 2004, the Environmental Protection Agency conducted a study on the possibility of tainted drinking water due to hydraulic fracking. The study concluded that the process was indeed safe and did not require further analysis to establish reliability due to the lack of "unequivocal evidence" for any health risks. However, the study was not to be generalized for all hydraulic fracturing operations, but only for specific coalbed methane deposits.

A 2011 a peer-reviewed study tested methane concentrations in water samples. On average methane concentrations tested 17 times above normal in samples taken from water wells near shale gas drilling sites employing hydraulic fracturing. Water samples from 68 private water wells in the states of Pennsylvania and New York were tested and some were found to have extremely high concentrations of methane: 64 milligrams of methane per liter of drinking water, compared with a normal level of one milligram or lower.

These studies provide evidence to cease, or severely limit hydraulic fracking. However many scientists believe that the benefits outweigh the costs. Natural gas is the cleanest fossil fuel in terms of carbon emissions to efficiency. Utilizing these natural resources can help slow the approach of climate change by reducing carbon dioxide emissions by up to 17 percent. Natural gas also has the potential to satiate energy demands until alternatives are in place and further developed. Many believe that although these are valid points, they are not valid enough to risk the safety of a states water supply.

The EPA has ventured onto a new study regarding hydraulic fracturing. The study aims to examine the effects of hydraulic fracturing on the water supply, specifically for human consumption. The research aims to examine the full scope of the water pathway as it moves through the hydraulic fracturing process, including water that is used for the construction of the wells, the fracturing mixture, and subsequent removal and disposal. Research is set for completion by the end of 2012. The EPA's Hydraulic Fracturing Report is projected for completion in 2014.

* Wellbore definition: Any hole drilled for the exploration or extraction of natural resources such as water, gas, or oil where a well may be produced and a resource is extracted for a protracted period of time.

Sources:

http://www.naturalgas.org/naturalgas/extraction.asp

http://www.scientificamerican.com/article.wastewater-sediment

http://www.syracuse.com/news/index.ssf/2010/hydrofrack.html

http://enwiki/Hydraulic_fracturing_in_the_United_States

Images:

http://www.ucsusa.org/clean_energy/water-energy-electricity-natural-gas.html