Hydraulic fracturing is a well stimulation technique in which rock is fractured by a pressurized liquid.
Well stimulation is a well intervention performed on an oil or gas well to increase production by improving the flow of hydrocarbons from the drainage area into the well bore.
Hydraulic fracturing: How it works by ExxonMobil
The process involves the high-pressure injection of 'fracking fluid' into a wellbore to create cracks in the deep-rock formations through which natural gas, petroleum, and brine will flow more freely.
Natural gas is a naturally occurring hydrocarbon gas mixture consisting primarily of methane, but commonly including varying amounts of other higher alkanes, and sometimes a small percentage of carbon dioxide, nitrogen, hydrogen sulfide, or helium.
Petroleum is a naturally occurring, yellow-to-black liquid found in geological formations beneath the Earth's surface, which is commonly refined into various types of fuels.
Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed.
Animation of Hydraulic Fracturing (fracking) by MarathonOilCorp
When the hydraulic pressure is removed from the well, small grains of hydraulic fracturing proppants hold the fractures open.
A proppant is a solid material, typically sand, treated sand or man-made ceramic materials, designed to keep an induced hydraulic fracture open, during or following a fracturing treatment.
Hydraulics is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids or fluids.
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.
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite.
Tight gas is natural gas produced from reservoir rocks with such low permeability that massive hydraulic fracturing is necessary to produce the well at economic rates.
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams.
Its proponents advocate the economic benefits of more extensively accessible hydrocarbons.
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon, and thus are group 14 hydrides.
Opponents argue that these are outweighed by the potential environmental impacts, which include risks of ground and surface water contamination, air and noise pollution, and the triggering of earthquakes, along with the consequential hazards to public health and the environment.
Public health refers to "the science and art of preventing disease, prolonging life and promoting health through organized efforts and informed choices of society, organizations, public and private, communities and individuals."
An earthquake is the perceptible shaking of the surface of the Earth, resulting from the sudden release of energy in the Earth's crust that creates seismic waves.
Noise pollution or noise disturbance is the disturbing or excessive noise that may harm the activity or balance of human or animal life.
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, and produced formation brine.
For these reasons, hydraulic fracturing is under international scrutiny, restricted in some countries, and banned altogether in others.
The European Union is drafting regulations that would permit the controlled application of hydraulic fracturing.