overview of possible impacts from coal seam gas
development in Northern Rivers, New South Wales
Project by Elfian Schieren, 2012
4.2 Water produced by coal seam gas
Water produced by CSG extraction contains compounds from
fraccing and/or drilling fluids and mobilised heavy metals, hydrocarbons and
radioactive elements from within the coal seam (NTN, 2011).
Many of the compounds both used in fraccing and drilling are
not being clarified by CSG companies in their public information as they are
considered to be industry "secrets" (NTN, 2011).
According to the CSIRO (2011) the water produced from the coal
seam can be strongly saline containing mostly sodium chloride but also sodium
bicarbonate and other compounds.
Research has found traces of highly toxic BTEX chemicals in an
Arrow Energy fraccing operation in QLD. BTEX stands for benzene, toluene,
ethylbenzene and xylene constituting a compound that is naturally found 14
in fossil fuel deposits such as coal and has also been used in
fraccing fluids (NTN, 2011). The QLD and NSW government have now banned the use
of BTEX in fraccing fluids (NTN, 2011).
Chemicals still commonly used in fraccing fluids in Australia
are listed in Table 1.
Approximately 200,000L of fluid can be used during a fraccing
treatment and even a very small amount of benzene has the potential to poison
thousands of litres of water (NTN, 2011).
Drilling fluids contain many compounds including biocides,
corrosion inhibitors, salts (sodium chloride, zinc bromide, calcium chloride,
potassium chloride), barium sulphate, emulsifiers, sodium hydroxide, potassium
hydroxide, amides, bactericides, ammonium bisulphate and sodium sulphate amongst
These compounds vary in toxicity levels and health effects (IPIECA
and OGP, 2009)
Table 1. Types of Chemicals Commonly Used in Fraccing Fluids
in Australia (NTN, 2011).
Table 1. Types of
Chemicals Commonly Used in Fraccing Fluids in Australia
Acid, Muriatic Acid
Glutaraldehyde, Tetrakis hydoxymethol phosphonium
Eliminates bacteria in water that produce
break gel polymer
methanol, naphthalene, naptha,
nonyl phenol, acetaldhyde
Prevents corrosion of pipes
friction of fluid
potassium carbonate Ethylene glycol
Sodium or potassium carbonate Isopropanol,
Prevents scale deposits in pipe
viscosity of fluid
Affects viscosity of fracking fluid
Figure 5. Historic Water Production from
Petroleum and Gas Wells in the Surat Cumulative Management (Queensland Water
Water production figures (Figure 5) from
1995-2010 state that over 20,000ML/year is produced from CSG activities within
the Surat Basin alone (Queensland Water Commission, 2012).
Figure 5 show that CSG developments have
caused a dramatic increase in petroleum industry water production since the
Surat Basin developments around 2005.
Most produced water is expected to be
treated and used or injected into aquifers or reinjected into the coal seam
(Arrow Energy, 2012).
Produced water is treated using reverse
osmosis which involves forcing water through a semi-permeable membrane to remove
The process has limitations in its ability
to remove organic compounds, being capable of removing only those above a
certain size (Bodalo-Santoyo et al., 2004).
The reverse osmosis technology also
involves large capital and operating costs particularly in energy and materials
and there still remains the issue of having to dispose of precipitated salts and
contaminants (Greenlee et al., 2009).
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