Fracking, or hydraulic fracturing, is a process of extracting oil and natural gas from underground shale formations, by inducing the formation of fissures along the shale rock. These cracks are induced by pumping hydraulically pressurized fluids through the formations. The nature and composition of this fracking fluid is elucidated in this article.
Heavy Load
Approximately 1-8 million gallons of water is used, per fracking event.
Hydraulic fracturing (also known as hydrofracturing, hydrofracking, or fracking) involves injecting shale formations with pressurized fluids to release trapped oil and gas reserves. The fluid used for this purpose is a mixture of water, sand, and a variety of chemicals. The chemicals to be used are based on the type of shale formations surrounding the fuel reserves.
The water in the fluid acts as a transporting agent for the chemicals and the sand. The sand acts to keep the fissures, caused by the pressurized nature of the injected fluid, to remain open. The different chemicals kill bacteria and other microbes, and help in dissolving minerals found in the shale. With various possible chemicals that can be used, each company maintains its own tried and tested blend of chemicals to be used for the process. However, there are a few chemicals that are commonly and routinely used by all companies that carry out fracking. Each chemical serves a purpose and can be classified accordingly.
Types of Chemical Functions
Acid
Dissolves minerals and helps induce cracks in the rock.
Biocide
Kills any water-borne bacteria, whose by-products may be corrosive.
Breaker
Stabilizes the gel, and enables its delayed breakdown.
Clay Stabilizer
Stabilizes the clay among the shale formations, and prevents it from swelling or shifting.
Corrosion Inhibitor
Prevents the corrosion of the fluid injecting pipe.
Crosslinker
Stabilizes and maintains fluid viscosity in case of rise in temperature.
Friction Reducer
Reduces the friction between the fluid and the pipe, and also between the fluid and its components.
Gelling Agent
Causes gel formation such that sand particles are homogeneously suspended throughout.
Iron Control
Prevents the metal oxides from precipitating.
Non-emulsifier
Prevents the formation of emulsions in the fluid.
pH Adjusting Agent
Maintains the pH at a level that is optimum for the other functions to occur.
Scale Inhibitor
Prevents the formation and deposit of scales in the pipe and fissures.
Surfactant
Acts as a detergent and also increases the viscosity of the fluid.
List of Chemicals Used in Fracking
| Chemical Name | Common Name | Function & Chemical Purpose |
| 2-Butoxyethanol | – | Surfactant Product Stabilizer |
| Acetaldehyde | – | Corrosion Inhibitor |
| Acetic Acid | Vinegar | Iron Control pH Adjusting Agent |
| Ammonium Persulfate | – | Breaker |
| Borate Salts | – | Crosslinker |
| Boric Acid | – | Crosslinker |
| Calcium Chloride | Ice Bite | Breaker Product Stabilizer |
| Choline Chloride | – | Clay Stabilizer |
| Citric Acid | Lemon / Lime Juice | Iron Control |
| Copolymer of Acrylamide and Sodium Acrylate | – | Scale Inhibitor |
| Ethanol | Grain Alcohol | Surfactant Product Stabilizer Winterizing Agent |
| Ethylene Glycol | Antifreeze | Breaker Product Stabilizer Winterizing Agent Friction Reducer Gelling Agent Non-emulsifier |
| Formic Acid | – | Corrosion Inhibitor |
| Glutaraldehyde | Diswart | Biocide |
| Hydrochloric Acid | – | Acid |
| Hydrotreated Light Petroleum Distillate | – | Carrier for Borate and Zirconate (Crosslinker) Carrier for Polyacrylamide (Friction Reducer) Carrier for Guar Gum (Gelling Agent) |
| Hydroxyethyl Cellulose | Guar Gum | Gelling Agent |
| Isopropanol | Rubbing Alcohol | Product Stabilizer Winterizing Agent Corrosion Inhibitor Non-emulsifier Surfactant |
| Lauryl Sulfate | – | Non-emulsifier Surfactant |
| Magnesium Oxide | Magnesia | Breaker |
| Magnesium Peroxide | Magnesium Dioxide | Breaker |
| Methanol | Wood Alcohol | Product Stabilizer Winterizing Agent Corrosion Inhibitor Crosslinker Friction Reducer Gelling Agent Surfactant |
| Naphthalene | Mothballs | Surfactant |
| Petroleum Distillate | – | Carrier for Borate and Zirconate (Crosslinker) Carrier for Polyacrylamide (Friction Reducer) Carrier for Guar Gum (Gelling Agent) |
| Phosphoric Acid Salts | – | Scale Inhibitor |
| Polyacrylamide | PAM Soil Conditioner | Friction Reducer |
| Polysaccharide Blend | – | Gelling Agent |
| Potassium Carbonate | Potash | pH Adjusting Agent |
| Potassium Hydroxide | Caustic Potash | pH Adjusting Agent |
| Potassium Metaborate | – | Crosslinker |
| Quaternary Ammonium Chloride | – | Biocide |
| Sodium Carbonate | Washing Soda | pH Adjusting Agent |
| Sodium Chloride | Table Salt | Product Stabilizer Breaker Clay Stabilizer |
| Sodium Erythorbate | Erythorbic Acid | Iron Control |
| Sodium Hydroxide | Lye | pH Adjusting Agent |
| Sodium Polycarboxylate | – | Scale Inhibitor |
| Sodium Tetraborate | Borax | Crosslinker |
| Tetrakis Hydroxymethyl Phosphonium Sulfate | – | Biocide |
| Tetramethyl Ammonium Chloride | – | Clay Stabilizer |
| Thioglycolic Acid | Mercaptoacetic Acid | Iron Control |
| Triethanolamine Zirconate | – | Crosslinker |
| Zirconium Complex | – | Crosslinker |
Why are Chemicals Used in Hydraulic Fracturing?
Chemicals are used in the fracking process to make the fracturing of shale and recovery of gas an efficient process. Their use eliminates the need for further processing of the recovered gas. If chemicals were not used, one would have to regularly carry out the tedious task of cleaning out the pipes due to deposition and precipitation of minerals, and also the action of bacterial byproducts. Also such depositions in the shale quarry itself would lead to inefficient recovery and re-entrapment of the natural gas. In addition, if friction reducers are not added, it would require more pressure and force to pump the water and sand mixture down to the rock bed. In the absence of clay stabilizers, there arises a possibility of the clay loosening and the tunnel collapsing. There is also a chance of decreased gas recovery due to the formation of emulsions.
After a well has been fracked, it is usually rinsed or flushed with pressurized water. All the injected fluids are recovered to some extent, and treated and recycled to reduce the toxicity levels. Newer ways are also being researched for possible reuse of the injected fracking fluid.