How Fracturing Works

Drilling

First a well is drilled vertically. Almost immediately after drilling, surface casing and cement is added at the start of the well followed by intermediate casing. Certain techniques are used to drill horizontally, which is becoming very common in shale plays, if needed.

Casing and Cementing

After the well is drilled, the production zone is lined with production casing, which is steel pipe, and secured with cement. This casing and cement protects groundwater from contamination of fluids flowing back up the wellbore, while also assisting in keeping the integrity of the wellbore.

Completion

Controlled shaped charges or a perforating gun are dropped into the well to start the fracing at the producing formation. Extensive amounts of water, chemicals, and sand are injected into the well under high pressure. This combination of water, chemicals and sand is known as the fracing fluid. The fracing fluid is composed of 99% sand and water and 1% is chemical additives that assist in the effectiveness of the fracture while also protecting the formation and casing from corrosion. The formation absorbs fluid at the rate of injection until it can't anymore. This high pressure causes the shale to fracture. Once the water pressure is released the sand in the mixture, known as the proppant, holds the fracture open allowing the natural gas to flow. Before the well is ready to produce, a majority of the fluids are brought back to the surface. These fluids are known as "flowback".