The basics process of hydraulic-fracturing
Hydraulic fracturing is a specific technique used by drilling companies to extract oil and gas from geological formations deep beneath the earth’s surface. The method involves breaking, or fracturing, the rocks (e.g. shale, sandstone etc.) that contain hydrocarbons, in order to release the oil and gas.
The typical process involves drilling an extremely deep well to a target formation a mile or two beneath the surface. If a horizontal well is being drilled, the well would then turn 90 degreees so that it runs horizontally to the surface for a few thousand feet, remaining in the target formation. The well is then lined with impermeable concrete, and explosives are dropped down the well in order to make perforations in the well at the depth of the target formation. Then, millions, of gallons of water, sand and chemicals are injected at high pressure into the well, causing fissures and cracks to form in the source rock where the well was perforated. The sand keeps the cracks open so that oil and gas can flow from the rock and up the well for recovery.