Wikipedia defines fracking in this way.
Hydraulic fracturing is the propagation of fractures in a rock layer, as a result of the action of a pressurized fluid. Some hydraulic fractures form naturally- certain veins or dikes are examples- and can create conduits along which gas and petroleum from source rocks may migrate to reservoir rocks. Induced hydraulic fracturing or hydrofracking, commonly known as fracking, is a technique used to release petroleum, natural gas (including shale gas, tight gas and coal seam gas), or other substances for extraction. This type of fracturing creates fractures from a wellbore drilled into reservoir rock formations.Hydraulic fracking isn't usually thought of as a disaster. I have listed it as such, because scientists are learning that it has serious side effects. If fracking becomes as common as people predict, the side effects will also become common and could thus be the basis for serious environmental harm to the earth. Here are some of the results of scientific investigation.
The first use of hydraulic fracturing was in 1947 but the modern fracking technique that made the extraction of shale gas economical was first used in 1997 in the Barnett Shale in Texas. The energy from the injection of a highly pressurized fracking fluid creates new channels in the rock, which can increase the extraction rates and ultimate recovery of hydrocarbons.
Proponents of fracking point to the vast amounts of formerly inaccessible hydrocarbons the process can extract. Opponents point to potential environmental impacts, including contamination of ground water, risks to air quality, the migration of gases and hydraulic fracturing chemicals to the surface, surface contamination from spills and flowback and the health effects of these. For these reasons hydraulic fracturing has come under scrutiny internationally, with some countries suspending or even banning it.
A new study in the journal Geology is the latest to tie a string of unusual earthquakes, in this case, in central Oklahoma, to the injection of wastewater deep underground. Researchers now say that the magnitude 5.7 earthquake near Prague, Okla., on Nov. 6, 2011, may also be the largest ever linked to wastewater injection. Felt as far away as Milwaukee, more than 800 miles away, the quake -- the biggest ever recorded in Oklahoma--destroyed 14 homes, buckled a federal highway and left two people injured. Small earthquakes continue to be recorded in the area.
In communities across the U.S., people are hearing more and more about a controversial oil and gas extraction technique called hydraulic fracturing -- aka, hydro-fracking. Controversies pivot on some basic questions: Can hydro-fracking contaminate domestic wells? Does it cause earthquakes? How can we know? What can be done about these things if they are true?
"We found measurable amounts of methane in 85 percent of the samples, but levels were 17 times higher on average in wells located within a kilometer of active hydrofracking sites," says Stephen Osborn, postdoctoral research associate at Duke's Nicholas School of the Environment. The contamination was observed primarily in Bradford and Susquehanna counties in Pennsylvania.
Hydrofracking wells expose nearby streams to loose sediments and hazardous fracturing fluids, and draw away large amounts of water. The technique forces high pressure fluid into dense rock, creating cracks through which trapped natural gas escapes and can be collected from the drill shaft. Developed in the 1940s, the technique gained wide application in the 1990s as gas prices rose and technology to drill horizontally away from a vertical well shaft made "unconventional" drilling profitable. Demand is up for natural gas because it burns cleaner than coal or petroleum, producing less greenhouse gas and smog.
The study, released at the annual meeting of the American Association for the Advancement of Science (AAAS) in Vancouver, British Columbia, found that many problems ascribed to hydraulic fracturing are related to processes common to all oil and gas drilling operations, such as casing failures or poor cement jobs.
The latest issue of CSA News explores the potential impact of fracking on Pennsylvania's forests as well as how the most troubling effects might be avoided or mitigated. Researchers have found, for example, that the heaviest gas development is occurring in the Susquehanna River basin -- the source of more than half the water flowing into the embattled Chesapeake Bay. And nearly 25% of shale gas wells have gone into Pennsylvania's last remaining tracts of unbroken, "core" forest, which is among the last intact forest in the entire Northeast, as well.
Most earthquakes in the Barnett Shale region of North Texas occur within a few miles of one or more injection wells used to dispose of wastes associated with petroleum production such as hydraulic fracturing fluids, according to new research from The University of Texas at Austin. None of the quakes identified in the two-year study were strong enough to pose a danger to the public.
Risk analysts have concluded that the disposal of contaminated wastewater from hydraulic fracturing (or "fracking") wells producing natural gas in the intensively developed Marcellus Shale region poses a substantial potential risk of river and other water pollution. That conclusion, the analysts say, calls for regulators and others to consider additional mandatory steps to reduce the potential of drinking water contamination from salts and naturally occurring radioactive materials, such as uranium, radium and radon from the rapidly expanding fracking industry. The new findings and recommendations come amid significant controversy over the benefits and environmental risks associated with fracking. The practice, which involves pumping fluids underground into shale formations to release pockets of natural gas that are then pumped to the surface, creates jobs and promotes energy independence but also produces a substantial amount of wastewater.