Because fluid contents will vary based on geographic and geologic factors, there is no “standard” formula for fracturing fluids. Generally speaking, most formulas consist of 0.5 to 2 percent chemical additives and 98 to 99 percent water and sand.
Although there are hundreds of chemicals that may be used in hydraulic fracturing, the vast majority of fracture jobs use a relatively small number of these chemicals. The pie chart below represents a generalized breakdown of the components in a typical fracture job.
What is fracturing fluid composed of?
Fluid Composition %
Commonly Used Chemicals and Their Purposes
The following includes the chemical types most frequently used in hydraulic fracturing, organized alphabetically. You can find the chemical name and CAS number here for many of the chemicals used.
Helps dissolve minerals and initiate cracks in the rock. Acid reacts with natural minerals to create salts, water and carbon dioxide. It’s also used as a corrosion inhibitor in well casings – when injected, it bonds to metal surfaces. Remaining product that does not bond is broken down and returned in produced water.
Eliminates bacteria that can cause corrosive byproducts by reacting with microorganisms that may be present in the treatment fluid and formation. Trace amounts of broken-down product are returned in produced water.
Base Carrier Fluid
Water that creates the fracture’s geometry and carries the sand that will hold it open. Residual fluid and sand that do not stay in the formation are returned in produced water.
Used to make it easier for fluid to flow through the borehole by creating a reaction with the crosslinker and gel, breaking down the gel. Ammonia and sulfate salts, produced as a result of the reaction, are returned in produced water.
Clay and Shale Stabilizer
Reacts with clays in the formation, stabilizing and locking them down in the shale. This reaction creates sodium chloride (table salt), which is returned in produced water.
A formula consisting primarily of borate salts that combines with the breaker and gel to break down gels and create salts that are returned in produced water. It also maintains viscosity as temperature increases and helps to prevent corrosion.
Reduces the effects of friction in the pipe. It remains in the formation, where it can be broken down by high temperature and exposure to the breaker; this allows it to be nearly completely consumed by microorganisms, with trace amounts returning in produced water.
Thickens water to ensure the sand is able to keep the fracture open. Also breaks down as a result of reaction with the crosslinker and breaker, ensuring easier flow of fluid to the borehole.
Turns iron in the water soluble to help prevent precipitation of metal oxides. Also reacts with minerals in the formation to create simple salts, carbon dioxide and water, all of which are returned in produced water.
Breaks up or separates oil-and-water mixtures that can clog the borehole. The majority of non-emulsifiers are returned with produced water, but some formations cause it to enter the gas stream and return in the produced natural gas.
Reacts with acidic agents in the treatment fluid to maintain a nonacidic, nonalkaline pH balance, helping to maintain the effectiveness of other additives. This reaction results in mineral salts, water and carbon dioxide, which are returned in produced water.
“Props” the cracks in the rock open as the fracturing fluid is withdrawn. Proppants typically consist of different types of sand or ceramic beads; whose granular consistency prevents the cracks formed during hydraulic fracturing from closing once the pumping pressure is released.
Helps to prevent scale buildup in the formation and in pipes by attaching itself to the formation. The majority of product returns with produced water; any that remains reacts with microorganisms, which break down and consume the product.
Reduces the surface tension of treatment fluid in the formation; it also helps improve fluid recovery from the well upon completion. Depending on the formula used, surfactants may react with the formation, be returned with produced water, or enter the gas stream and return with produced natural gas.
Chemical Names: Eliminating Confusion
Searching for chemicals by CAS Registry Number can help eliminate confusion caused by multiple names for the same chemical. Additionally, you can find a list of alternate chemical names listed by CAS number at the following websites. (Please note that when you click these links, you will leave the FracFocus website. The listed websites are not controlled by or affiliated with FracFocus.)