Hydraulic fracturing is the fracturing of rock by a pressurized liquid. Some hydraulic fractures form naturally. Hydraulic fracturing is a well-stimulation technique in which a high-pressure fluid (usually water mixed with sand and chemicals) is injected into a wellbore in order to create small fractures (usually less than 1.0 mm wide) in the deep-rock formations in order to allow natural gas, petroleum, and brine to migrate to the well. When the hydraulic pressure is removed from the well, small grains of hydraulic fracturing proppants (either sand or aluminium oxide) hold open the small fractures once the deep rock achieves geologic equilibrium. The fracking technique is commonly applied to wells for shale gas, tight gas, tight oil, and coal seam gas. Such well-stimulation usually is done once during the productive life of the well, and greatly assists in removing fluids (gas, petroleum), and thus increases the productivity of the well; often, multiple application of induced hydraulic fracturing (and/or other well-stimulation techniques) are used as the field's production declines. The first, experimental use of hydraulic fracturing was in 1947, and the first, commercially successful applications of fracking were in 1949. Worldwide, as of 2012, 2.5 million hydraulic fracturing jobs have been performed on oil and gas wells; more than one million jobs were performed in the U.S.
Last date updated on July, 2014