Hydraulic fracturing (fracking) is a technique used to crack rock underground, usually for the purpose of extracting oil or gas.
It involves injecting a fluid down a well under massive pressure, in order to force open cracks in the targeted rock. More recently “massive slickwater hydraulic fracturing” has been developed for the purpose of extracting gas from more much impermeable rock formations, such as shale. In conventional extraction the oil or gas flows through permeable formations and one well can drain a large area. Unconventional extraction requires large numbers of wells, which each drain a small area (40-80 acres). Hydraulic fracturing requires the use of around 5 to 7 million gallons of slickwater (a mixture of water, sand and chemicals) to fracture the rock.
Unconventional gas extraction has three different processes; shale gas, coal bed methane (CBM) and underground coal gasification (UCG). There are a lot of differing techniques for these processes, but all involve drilling large numbers of wells at regular intervals. The scale of these new, more intense methods would require hundreds of wells to be drilled. Shale gas and oil require massive slickwater hydraulic fracturing to be carried out on every well. Millions of gallons of fresh water, sand and toxic chemicals are injected under massive pressure. These wells also have much shorter lifespans, as production from a typical shale well declines by 70 to 80 percent in the first year alone. This means that large numbers of new wells need to be constantly drilled to maintain production, even for short periods.