Chemicals used in hydraulic fracturing

Chemicals play an important role in the oil and gas industry. The use of chemicals is regulated by the Commonwealth and State Governments to ensure chemicals are handled, stored, transported and disposed of in a safe and environmentally responsible manner.

Why are chemicals used in hydraulic fracturing?

During hydraulic fracturing, fluid is pumped down a well at pressure to create small fractures (cracks) in gas-bearing rock formations to release trapped petroleum. In Western Australia (WA), these rock formations are typically two to five kilometres underground.

The fluid typically contains up to 90 per cent water, up to 9.5 per cent sand/proppants and up to 0.5 per cent chemicals. Water is used to create pressure to fracture the rock. It is also used to transport sand and chemicals through the well.

Sand/proppants hold the fractures open and increase the amount of petroleum that can flow through the rock. Typically, chemicals are added to improve the transportation of sand, prevent the growth of bacteria, reduce mineral or chemical blockages and to avoid well corrosion.

How are chemicals assessed?

Chemicals are regulated by the Commonwealth Government of Australia through the National Industrial Chemicals Notification and Assessment Scheme (NICNAS). This regulatory body assesses the risks of all chemicals made or brought into Australia, and sets conditions about their safe use to protect people and the environment.

The State Government assesses the chemicals proposed in hydraulic fracturing, including the risks to safety, environment and public health, and checks that the chemicals used in hydraulic fracturing have been approved for use in Australia. There are arrangements in place between the Environmental Protection Authority (EPA), the Department of Mines, Industry Regulation and Safety (DMIRS), the Department of Health, and the Department of Water and Environmental Regulation to obtain advice on the risks.

Hydraulic fracturing proposals are not allowed to proceed if the chemicals pose unacceptable public health, safety and/or environmental risks (including risk to groundwater).

The chemicals are assessed against:

  • toxicity to humans;
  • toxicity to the environment;
  • biodegradation, bioaccumulation potential and persistence;
  • potential chemical routes and exposure pathways; and
  • health and environmental standards.

What types of chemicals are used during hydraulic fracturing?

The chemicals are typically used in very low concentrations by volume (between 0.1 to 0.5 per cent). Exact chemical mixtures will vary and depend on several factors including the depth and the properties of the rock being targeted.

The types of chemicals and their purpose in the hydraulic fracturing operation are detailed below:


Chemical types

What it is used for



Biocide, microbial controls

Limits the growth of bacteria in the water which may reduce flow rates and contribute to well corrosion


Breaks down the gelling agents and releases the proppant into rock fractures

Clay inhibition, stabiliser

Counters clay swelling in the well when drilling and in the rocks being fractured to optimise drilling and flow rates

Friction reducer

Reduces the friction forces of fluids being pumped into the well to increase flow-rates

Gelling agent, binder, crosslinker

Increases the thickness of fluids which allows  more proppant to be carried into rock fractures

Iron control, scale control

Limits the build-up of iron precipitates and mineral scale which can reduce the flow rate of fluids and contribute to well corrosion

Oxygen scavengers, corrosion inhibitors

Removes or deactivates oxygen and other corrosive material in fluids which contribute to well corrosion


Tiny solids (e.g. sand) are used to physically hold open tiny rock fractures or cracks and to allow fluids and gas to move around them

pH control, buffers, acids, salts, stabilisers, solvents

Adjusts the chemical and physical properties of the fluid to achieve optimal flow rates


Reduces the stickiness of fluids to improve flow rates


How can I find out what chemicals are being used in hydraulic fracturing?

The State Government publishes this information on the relevant department’s website.

If a proposal is being assessed by the EPA, the information will be available from the EPA's website. If the proposal is being assessed by DMIRS, the information will be available from the DMIRS’ website in the Environment Plan Summaries.

Petroleum companies are also required, under the Petroleum and Geothermal Energy Resources (Environment) Regulations 2012, to consult with relevant interested persons and organisations. For hydraulic fracturing, companies are expected to engage with their stakeholders about the chemicals they propose to use.

How are chemicals stored onsite and disposed of?

All chemicals stored on an oil or gas site must comply with the management practices specified in the Safety Data Sheets to ensure safe chemical storage, transport, use and disposal.

The requirements typically include storage of chemicals in purpose-built lined and bunded areas designed to Australian Standards, to contain any potential spills or leaks.

A bund is a structure with a floor and retaining wall that envelopes the area where chemicals are handled, processed or stored. Its purpose is to minimise the risk of unintended escape of undiluted chemicals into the environment and to retain any spillages for clean-up.

After fluid has been used down a well, the waste water (flow-back water) returned to the surface can be re-used in another hydraulic fracturing operation or be stored in lined water evaporation ponds. This prevents waste water from seeping into groundwater, and allows left-over material to be tested and then removed by a licensed waste contractor for disposal at a waste facility licensed under the Environmental Protection Act 1986.

Chemicals used in hydraulic fracturing

A range of chemicals are used in the hydraulic fracturing process and many of them are used in industrial processes and household products. Some of the substances, or active ingredients, may be hazardous and can be dangerous if used in high concentrations and/or unsafely.

The number of chemicals used in hydraulic fracturing, each serving a specific purpose, depends on the specific well location and characteristics of the target formation. Hydraulic fracturing fluid typically contains very low concentrations of between three and 12 chemical products. The tables below describe some of the substances that may be used in hydraulic fracturing, and other common applications.


Chemical name

Other applications

Crystalline silica (Quartz)

Cat litter, tile mortar, arts and crafts, glass manufacture, ceramic glaze, glaze, concrete, paint

Crystalline silica (Cristobarite)

Sand, gravel


Dinnerware, glassware, tiles, pottery, electronic devices



Chemical type or name

Other applications


Medical and dental disinfectant, wart treatment

Tetrakis(hydromethyl) phosphonium sulphate

Fabric treatment, leather tanning

Quaternary ammonium chlorides
(e.g. benzoalkonium chloride, benzethonium chloride)

Disinfectants, anti-mould removal, throat lozenges, swimming pool algaecide

Chloromethylisothiazolinone (CMIT)

Cosmetics, shampoos, conditioners, body washes, disposable wipes

Methylisothiazolinone (MIT)

Toiletries, cosmetics, dishwashing liquids

Sodium hypochlorite

Disinfectant, bleaching agent, cleaners, milk production, water treatment, dental sterilisation, medical use, wood cleaner/deck wash, mildew remover, phosphate free dishwasher gel, anti-bacterial cleanser


Oxygen scavengers / corrosion inhibitors

Chemical name

Other applications

Zinc carbonate

Shampoos, skin protectants and cosmetics


Cleaning agent for electronic components, whiteboard cleaner, hand sanitiser


Petrol additive

Formic acid

Clothing dye, cleaning products


Preserving fish and fruit; perfume production, plastics and dyes


Capsules for medicines, desserts, jellies, ice cream

Sodium sulphite

Food preservatives, making dyes, making paper and textiles


Iron control / scale control chemicals

Chemical name

Other applications

Citric acid

Flavour enhancer, cleaning products, pharmaceutical applications

Acetic acid

Vinegar, found in citrus fruits, descaling products

Thioglycolic acid

Hair perming and straightening, leather processing

Sodium erythorbate

Used in processed meats, poultry and soft drinks

Acrylamide copolymer / sodium acrylate

Used in paper making, dyes and plastics

Sodium polycarboxylate


Phosphoric acid salt

Anticorrosion products


pH control, buffers, salts, stabilisers, solvents

Chemical type or name

Other applications

Potassium carbonate

Soaps, glass and china production

Sodium acetate

Food flavouring

Sodium hydroxide (caustic soda)

Food preparation, household drain cleaner, paper, soaps, detergents

Sodium bicarbonate

Baking soda, cleaning product

Sodium carbonate (soda ash)

Water softener, swimming pools, food additive, glass

Hydrochloric acid

Household cleaning, food additive, swimming pools, drinking water

Carbonic acid

Soda drinks

Citric acid

Flavour enhancer, cleaning products, pharmaceutical applications

Sodium acid pyrophosphate (SAPP)

Food preservative

Acetic acid

Vinegar, found in citrus fruits, descaling agent

Carbonic acid, sodium salt

Food additive

Calcium chloride

Detergents, cosmetics, deodorant, pet products, dessicant (moisture absorber), food additive, sports drinks

Gypsum (calcium sulphate)

Fertiliser, plasterboard

Ethylene glycol

Clothing manufacturing, car coolant, cooling systems

Magnesium silicate hydrate (talc)

Talcum powder, cosmetics, food additive, soaps, paper, paints, rubber, pottery

Tetrasodium ethylenediaminetetraacetate


Magnesium oxide

Cements, antacid medicine


Friction reducers

Chemical type or name

Other applications


Water absorbing toys

Hydrotreated light petroleum distillate

Mineral turpentine


Petrol additive

Ethylene glycol

Clothing manufacturing, car coolant, cooling systems

Sodium lignosulphonate

Food preservative, used in ceramics, making paper and leather


Food and pharmaceutical industry, hair products


Clay management chemicals

Chemical type or name

Other applications

Sodium chloride

Table salt


Cleaning electronics, whiteboard cleaner, hand sanitiser

Tetramethyl ammonium chloride

Batteries, antiseptic agent, plastic manufacturing

Potassium chloride

Table salt substitute, some medical treatments, garden products, pet supplements, various hair products


Water absorbing toys

Choline chloride

Poultry feed additive

Polydimethydiallyl ammonium chloride

Water treatment (drinking and waste-water), textiles, cosmetics, paper making, soil treatment, drinking, bathing, cooking

Trimethylammonium chloride


Magnesium nitrate

Facial care, home garden uses, ceramics

Magnesium chloride

Food industry (e.g. tofu from soy milk), vitamin supplements

Silica gel

Cat litter, packaging, food preservative

Poly(ethylene glycol co-propylene glycol) monobutyl ether

Lubricants, plastic manufacturing


Gelling agents / binders / crosslinkers

Chemical type or name

Other applications


Cement, adhesives, ceramics, cat litter, wine making

MEA borate

Cosmetics, hair texturiser, hairspray, antiseptic, laundry detergent

Boric acid

Cosmetics and skin care products


Cosmetics and skin care products

Sodium tetraborate

Detergents, cosmetics, texturing agent in cooking

Vinylidene chloride / methylacrylate

Plastic wrap

Sodium chloride

Food production, food additive, detergents, hair products, water softener

Hydrogen peroxide

Hair bleach, food processing

Diammonium peroxidisulphate

Hair bleach

Sodium thiosulphate

Personal care, pet care, food production, aquaculture food

Sodium sulphate


Sodium sulphite

Paper industry

Carboxymethyl cellulose (cellulose gum)

Thickener in dressings, sauces, ice cream, cosmetics, eye drops, ice-packs

Welan gum

Food additive

Guar gum

Thickener in dairy products, sauces and dressings, cosmetics, baked goods, ice cream, toothpaste

Xanthan gum

Thickener in dressings, sauces, ice cream, cosmetics

Polysaccharide blend (starch)

Naturally present in all plants and animals



Chemical type or name

Other applications

Sodium persulphate

Hair bleach

Hemicellulase enzyme

Food industry, washing powder

Hemicellulase enzyme carbohydrates

Food additive

Ammonium persulphate

Hair bleach

Sodium chloride, salt

Table salt

Magnesium oxide

Cements, antacid medicine



Chemical type or name

Other applications


Cleaning agents, jewellery cleaner


Present in beer, wine and spirits


Cleaning agents

C6-C10 Alcohol ethoxysulphate

Laundry detergents

Alcohols C6-C10 ethoxylated (surrogate C6-C12)

Cleaning agents

Lauryl sulphate



Terms used

hydraulic fracturing: also known as hydraulic fracture stimulation or ‘fracking’, this means the underground petroleum extraction process that involves the injection of fluids under high pressure into low permeability rock to induce fractures for the purpose of increasing the rock’s permeability. This term is as defined in the Petroleum and Geothermal Energy Resources (Hydraulic Fracturing) Regulations 2017.

permeability: the ability, or measurement of a rock’s ability to transmit fluids.

petroleum: a complex mixture of naturally occurring hydrocarbon compounds found in rock in liquid, gaseous or solid form (i.e. crude oil, natural gas, or bitumen).

proppant: small particles, usually sand, mixed with fracturing fluid to hold fractures open after a hydraulic fracturing treatment.