Topics on this page include:

• Fracturing Fluid Functions
• Fracturing Fluid Composition
• Fracturing Fluid Chemical Additives

Fracturing Fluid Functions

Fracturing fluid is important to the hydraulic fracturing process. Fracturing fluid:

• Applies pressure to the formation
• Initiates fractures in the formation
• Delivers proppant to the fractures

Fracturing Fluid Composition

Fracturing fluid is important to the hydraulic fracturing process. Fracturing fluid:

• Applies pressure to the formation
• Initiates fractures in the formation
• Delivers proppant to the fractures

Fracturing fluid can be made up of a base fluid, proppant and chemical additives.

• The base fluid applies pressure to the formation and delivers the proppant and additives to the fractures. Base fluids used in hydraulic fracturing include:
  • Water
  • Oil
  • Methanol
  • Liquid carbon dioxide
  • Liquefied petroleum gas
• Proppant consists of solid particles that hold open the fractures created by hydraulic fracturing, allowing the oil or gas to flow out of the formation and into the well. Proppants used in hydraulic fracturing include:
  • Sand
  • Sintered (heated) bauxite
  • Ceramics
  • Resin-coated sand
• Chemical additives are formulations of one or more chemicals that are added to a fracturing fluid to protect equipment, reduce pumping requirements and maintain the integrity of the oil or gas formation. Different sites/formations may use different chemical additives. Examples of chemical additives known to have been used in fracturing include the following. This list is not comprehensive and may change over time:
  • Friction reducers (e.g., polyacylamide, kerosene, isopropanol)
  • Biocides (e.g., glutaraldehyde, 2,2 dibromo-3-nitrilopropionamide (dbnpa), 2-bromo-2-nitro-1,3-propanediol (Bronopol))
  • Scale inhibitors (e.g., ethylene glycol, hydroxyacetic acid, polyacrylate)
  • Clay stabilizers (e.g., potassium chloride, ammonium chloride)
  • Surfactants (e.g., isopropanol, toluene, methanol)
  • Acids (e.g., hydrochloric acid, acetic acid, formic acid)
  • Corrosion inhibitors (e.g., n,n-dimethylformamide, ethylene glycol, propargyl alcohol)
  • Iron control agents (e.g., citric acid, isoascorbic acid, sodium erythorbate)
  • Gelling agents (e.g., guar gum, diesel, hydroxyproplyguar)
  • Crosslinkers (e.g., borate salts, diesel, triethanolamine zirconate)
  • Breakers (e.g., ammonium persulfate, sodium persulfate, ethylene glycol)
  • pH adjustors (e.g., sodium carbonate, hydroxyacetic acid, boric acid)
  • Foaming agents (e.g., nitrogen gas, ethanol, liquid carbon dioxide)

Fracturing Fluid Chemical Additives

Fracturing fluids typically contain numerous additives:

• Friction reducers minimize friction between the fracturing fluid and the pipe through which it is pumped, and reduce the pumping pressure required to complete the fracture
• Biocides inhibit microorganism growth in equipment and within formation fractures
• Scale inhibitors prevent mineral solids from precipitating out of fracturing and formation fluids and causing a buildup of minerals in equipment
• Clay stabilizers prevent clay in the formation from swelling
• Surfactants increase the viscosity of the fracturing fluid
• Acids dissolve minerals and debris left in the well after drilling
• Corrosion inhibitors prevent corrosion of lines and equipment
• Iron control agents prevent the precipitation of iron, which can block fluid flow in the formation
• Gelling agents thicken the fluid
• Crosslinkers maintain fluid viscosity as the temperature of the fluid increases
• Breakers break down the gelling agent and crosslinker and decrease fluid viscosity
• pH adjustors maintain the desired pH range
• Foaming agents aerate the fluid to create a foam