Fracking (also often referred to as hydraulic fracturing or hydrofracking) is a process stimulation procedure first used by the oil and gas industry in 1947 at a well in the Hugoton gas field located in Kansas. Hydraulic fracturing was first used commercially in 1949. The premise is simple, fluids are forced under pressure into the formation surrounding the wellbore. Once those fluids reach the fracture gradient of the surrounding rock the rock parts and fluid continues to flow further from the wellbore. The fluid continues to propagate the fracture, and eventually proppant is added to the fluid stream in order to keep the fractures from naturally healing once the wellbore pressure is released. Once the process is finished the now propped fractures provide conduits for fluids to flow to the wellbore.
To date hydraulic fracturing has been performed more than 1 million times in every oil and gas producing region in the country. It is estimated that of the existing wells in the United States hydraulic fracturing has been performed in more than 70% of them.
There were more than 493,000 active natural-gas wells across 31 states in the U.S. in 2009, almost double the number in 1990. Around 90 percent have used fracking to get more gas flowing, according to the drilling industry. Nationwide, residents living near fracked gas wells have filed over 1,000 complaints regarding tainted water, severe illnesses, livestock deaths, and fish kills.