Introduction
Hydraulic fracturing, known as fracking, is a means of natural gas extraction employed in deep natural gas well drilling. The fracturing is done from a wellbore drilled into reservoir rock formations. The rock layers are fractured when chemical-laced water and sand are blasted underground to break apart rock and release natural gas. The chemical based water is known as fracking fluid. The fracking fluid injected into the rock is typically a slurry of water, proppants, and chemical additives. Additionally, gels, foams, and compressed gases, including nitrogen, carbon dioxide and air can be injected. Various types of proppant include silica sand, resin-coated sand, and man-made ceramics. These vary depending on the type of permeability or grain strength needed. Sand containing naturally radioactive minerals is sometimes used so that the fracture trace along the wellbore can be measured. Chemical additives are applied to tailor the injected material to the specific geological situation, protect the well, and improve its operation, though the injected fluid is approximately 98-99.5% percent water. (Modern Shale Gas Development in the United States: A Primer, 2009) For each frack, 1-8 million gallons of water and 80 – 300 tons of chemicals may be used to frack a well. A well may be fracked up to 18 times. (Fox, 2010) Figure 1: Hydraulic Fracturing (Albertan, 2011)
History
Hydraulic fracking of oil and gas wells was first used in the United States in 1947. It was first used commercially in 1949 by Halliburton. Due to the success in increasing production from oil and gas wells, it was quickly adopted and used worldwide. (Smith, 2010). Hydraulic fracking has been used on over 1 million producing wells since its commercial development. As the technology has continued to develop and improve, an estimated 35,000 wells are fractured each year.