Hydraulic Fracturing

Hydraulic Fracturing

Hydraulic Fracturing, better known as fracking, is a process which allows natural gas to be extracted from the ground. The fracking process starts by drilling a hole into the ground called a borehole to a depth of about 7,700 feet where pockets full of natural gas are located. (1) Safety is a big concern during this process, therefore a steel casing is wrapped around the borehole along with an additional cement casing. This extra cement casing is a very important reinforcement layer that protects the groundwater level from any contamination that could occur if the steel were to crack. The groundwater level ranges from about 100-500 feet.(1) The drilling continues down through many different layers of earth and several thousand feet of solid rock. Limestone and shale are two examples of the layers that are drilled through.

Once the drilling reaches the depth of about 7,700 feet, a turn is taken until it reaches a horizontal position and continues forward for another mile. At this point the drilling process is complete and the next step is to send perforating tools down the hole with conductors that will shoot out shock waves through the shale.(1) The shock waves cause fractures or fissures to occur that will open up the shale layer. The perforating tools are then sent back up the surface and fracturing fluid is sent down. Water and sand make up 98 to 99.5 percent of the mixture used in hydraulic fracturing. The other percentage of fluid consists of chemical additives such as sodium chloride, ethylene glycol, borate salts, sodium/potassium carbonate and guar gum. (8) These fluids are also used in common household items as well as table salt, household cleaners, cosmetics, detergent, and ice cream. The mixture is created and sent down to the bottom of the borehole where the fractures are located. Pressure is then applied causing the fractures to expand. At this point in the process, the mixture is removed and taken to storage reservoirs. Sand particles from the mixture are left behind keeping the fractures open, making it easier for the natural gas to be extracted and brought to the surface. Once the natural gas is drawn out of the borehole and collected in reservoirs it is injected into trucks and sent off to other sights. (9)

After the fracking process is completed, about 20% to 40% of the fracking fluid flows back up to the surface and is disposed of by a number of different options.(7) The four most common disposal options are recycling for additional fracking use, underground injection, storage in open air pits, and the treatment and discharge to surface waters. These disposal processes are known to be very controversial. Injection is the most common disposal solution. Injection is where the flow back fluids from fracking are injected deep into the ground (up to 10,000 feet) underneath porous rock formations and are sealed both above and below by unbroken, impermeable