Hydraulic fracturing and the chemicals used

Hydraulic fracturing has been used in the oil and gas industry for more than 50 years and in Australia for several decades.

when drilling wells, grout or cement is pumped between the well casing (a steel tube) and the hole back to the surface. This forms a barrier between the coal seams and any nearby aquifers.

Hydraulic fracturing involves mostly water and sand that is injected into wells at high pressure to crack the coal seams so gas can flow more freely. The sand holds open the cracks. The process is designed to only affect the target coal seam. Like farmers who use chemicals on crops, QGC uses chemicals with extreme care.

The small proportion of chemical additives in hydraulic fracturing fluid are needed to reduce friction, remove bacteria, dissolve some minerals and enhance the fluid’s ability to transport sand. They consist mainly of commonly used compounds like:

• Surfactants (in soap or toothpaste)
• Guar gum (in ice cream)
• Sodium hypochlorite (in swimming pools)
• Hydrochloric acid (also in swimming pools)
• Acetic acid (basis of vinegar)

All chemicals are handled according to strict procedures by trained personnel and are used in concentrations so low as to cause no adverse environmental impact. The chemical product safety data sheets (SDS) are supplied in Table 1 below. Table 2 provides stimulation chemical risk assessments, prepared by an independent and qualified consultancy, that:

• identify the hazards associated with proposed stimulation chemicals;
• consider potential exposure pathways and the risk of potential impacts; and,
• determine the required management measures.

Note: The above tables are periodically updated with new chemical products and also to remove some that are obsolete. Chemical products are retained on the QGC website for at least a year following their use in hydraulic fracturing. For information about historical chemicals used in hydraulic fracturing please contact us.