Hydraulic fracturing (a "frac" or "fracing") is a technique used to allow oil and natural gas to move more freely from the rock pores where they are trapped to a producing well that can bring them to the surface. The technology was developed in the late 1940s and has been continuously improved and applied since that time. Fracing is a process that breaks apart the reservoir, effectively increasing the permeability of the reservoir. It is accomplished by pumping water under high pressure into the reservoir, sufficient to break apart the rock. The cost of hydraulic fracturing typically increases rapidly with the distance penetrated within the reservoir. An advantage of fracing is that it can be easily applied to an existing well bore. A disadvantage is that the artificial fractures created tend to run in a plane, rather than a radius, as shown below:

An advantage of fracing is that it can be easily applied to an existing well bore. A disadvantage is that the artificial fractures created tend to run in a plane, rather than a radius.