Hydraulic fracturing (also hydrofracturing, hydrofracking, fracking or fraccing) is a well-stimulation technique in which rock is fractured by a pressurized liquid. The process involves the high-pressure injection of ‘fracking fluid’ (primarily water, containing sand and other proppants suspended with the aid of gelling agents) into a wellbore to create cracks in the deep-rock formations through which natural gas, petroleum, and brine will flow more freely. When the hydraulic pressure is removed from the well, small grains of hydraulic fracturing proppants (either sand or aluminium oxide) hold the fractures open.

Hydraulic fracturing began as an experiment in 1947, and the first commercially successful application followed in 1950. As of 2012, 2.5 million “frac jobs” had been performed worldwide on oil and gas wells; over one million of those within the U.S. Such treatment is generally necessary to achieve adequate flow rates in shale gas, tight gas, tight oil, and coal seam gas wells. Some hydraulic fractures form can form naturally in certain veins or dikes.

Hydraulic fracturing is highly controversial in many counties. Its proponents advocate the economic benefits of more extensively accessible hydrocarbons. However opponents argue that these are out-weighed by the environmental impacts, which include the risks of contaminating ground and surface water; causing air and noise pollution and potentially triggering earthquakes, along with the consequential hazards to public health and the environment.

Increases in seismic activity following hydraulic fracturing along dormant or previously unknown faults are sometimes caused by the deep-injection disposal of hydraulic fracturing flowback (a byproduct of hydraulically fractured wells), and produced formation brine (a byproduct of both fractured and nonfractured oil and gas wells). For these reasons, hydraulic fracturing is under international scrutiny, restricted in some countries, and banned altogether in others. Some of the countries that have banned the practice, notably the U.K., contemplated repeal of bans on hydraulic fracturing in favor of regulation. The European Union is drafting regulations that would permit controlled application of hydraulic fracturing.

What are the fracking chemicals used?

In the United States, about 750 compounds have been listed as additives for hydraulic fracturing in a report to the US Congress in 2011 after originally being kept secret for “commercial reasons”. The following is a partial list of the chemical constituents in additives that are used or have been used in fracturing operations, as based on the report of the New York State Department of Environmental Conservation, some are known to be carcinogenic.

In the UK only ‘Non-Hazardous’ chemicals are permitted for fracturing fluids by the Environment Agency. All chemicals have to be declared publicly and, increasingly, food additive based chemicals are available to allow fracking to take place safely.

Additives used in the United States