What is Fracking?
Fracking, also known as hydraulic fracturing or fraccing, is a process used to extract gas trapped deep underground in tiny pockets of sand or between rocks.
An above ground rig is used to drill deep into the earth vertically and then horizontally. Fracking fluid, which is a mixture of chemicals, water and a proppant, such as treated sand or ceramics, is then injected into the hole at extremely high pressure. This causes the underground rocks to break up, or fracture, releasing the gas, which then travels back up the hole. The proppant remains behind trapped in the rock fractures to keep them open. Some of the fluid is lost down the hole the rest comes back to the surface as flow back. Underground water released in the fracking process is known as produced water and it too comes out of the hole.
Fracking is most often used to release gas trapped in tight sands or shale. It is also used to release some coal seam gas (CSG).
Fracking is controversial because of its potential environmental impact particularly because of the risk of the process contaminating groundwater aquifers.