The process of hydraulic fracturing (also known as fracking) has been used extensively to allow gas to be produced from previously uneconomic shale gas resources. The process begins with drilling a well vertically, and once the desired depth is reached the well is then drilled horizontally. After pipe has been inserted into the well and cemented in, perforations are made in the pipe and cement in the sections where gas flow is desired using a device called a perf gun. Next a mixture of fluids including water and chemical additives are pumped into the well at high pressure. The fluids flow through the pipe and out the perforations. Given the high pressure of the fluids, this causes fractures in the rock. In addition to the fluids, a solid material like sand or beads is injected to prop the cracks open. When the fluids are pumped back out of the well, gas flows into the pipe through the newly created fractures and then to the wellhead. This process can often allow economic gas production in formations that otherwise would not be economic to produce.
The gas and oil industry has used hydraulic fracturing for more than 60 years. There is no doubt that improved hydraulic fracturing, combined with new horizontal drilling capabilities, has unlocked huge amounts of economic gas supply. But lately, increased use of hydraulic fracturing has become controversial due to drilling in closer proximity to populated areas and public campaigns waged by opponents who believe it causes unacceptable environmental risks.
Like all industrial processes, there are risks. These include:
Different regions around the world have taken different positions on hydraulic fracturing for natural gas production. Some allow it with minimal regulation, some allow it with rather strict regulation, and some have entirely banned it. Examples of jurisdictions banning it as of 2020 include multiple U.S. states including New York and countries such as Bulgaria, France, Germany, and Ireland.