What is Fracking? Schematic depiction of hydraulic fracturing for shale gas. Hydraulic fracturing is an oil and natural gas production technique that involves the injection of millions of gallons of water, plus chemicals and sand, underground at very high pressure in order to create fractures in the underlying geology to allow natural gas to escape. Hydraulic fracturing, commonly called fracking, is a drilling technique used for extracting oil or natural gas from deep underground. Fracking is a hotly debated environmental and political issue. Hydraulic fracturing, or fracking, opened up more natural gas for production, but the technology added costs to the oil extraction process. Shale oil costs more than conventional oil to extract, ranging from a cost-per-barrel of production from as low as $40 to over $90 a barrel.