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Coal Seam Gas

Coal seam gas (CSG) is a naturally occurring methane gas, mixed with carbon dioxide, other hydrocarbons and nitrogen from coal formation. CSG is similar to conventional natural gas and can be used as an energy source for both domestic and business settings.

The CSG industry offers substantial economic benefits to Australia. Appropriate management and regulation will minimise any potentially adverse impacts on surface and groundwater systems, and air quality arising from emissions of methane, air toxics, ozone precursors and other pollutants. Planning, validation and ongoing verification monitoring are thus essential to improving the operational and environmental outcomes of CSG extraction.

There is no consensus method for proving or disproving the impact of CSG on groundwater. There are two reasons for this. Firstly, a wide range of chemicals can be used in the CSG extraction process. Secondly, and more importantly, some of the same compounds may occur naturally at varying levels in the groundwater that bathes coal seams. Thus biogenic and petrogenic compounds need unequivocal identification and accurate chemical quantitation to differentiate natural baselines from CSG activities.

CSG-associated water is a brackish matrix and, on average, salinity levels are between 200 and 10 000 mg/L of total dissolved solids (TDS) compared with 35 000 mg/L TDS in sea water. This matrix is a challenge for laboratory analysts, especially when requiring guideline values for the comprehensive list of water quality parameters specified by Queensland’s Department of Energy and Water Supply or where appropriate, the Australian Government’s National Water Quality Management Strategy Guidelines. Further, additional analysis may be required for CSG water that potentially contains chemicals used in fraccing. Fraccing is the process of fracturing and propping open the coal with hydraulic pressure and sand to enhance gas production.

Ambient air quality at CSG exploration and gas extraction sites may also require monitoring. For example, emissions from cold vents and fugitive releases from wells and un-combusted hydrocarbons when CSG is flared may need to be monitored for airborne toxicants as listed in the National Environment Protection (Air Toxics) Measure and dust emissions during site development may need to comply with Australian standards for ambient air particulate matter and workplace inhalable dust.

NMI’s Capabilities

NMI's analytical labNMI can offer fit-for-purpose measurement expertise and solutions for environmental impact assessments and regulatory compliance verification covering a full range of chemicals parameters applicable to CSG extraction. Our laboratory-based water and chemical testing capabilities can be applied to baseline quality testing of groundwater, ‘CSG-produced water’ and processed water prior to its re-injection, re-use or release to the environment. We also offer air quality testing for volatile organic compounds and specialist services in gas composition and gas reference standards for other laboratories. See the table for a list of our services.

Our laboratories have NATA accreditation for a wide range of services (NATA 198). Our limits of reporting are at, or below, the guideline value for complex sample matrices, enabling assessment for regulatory compliance. This includes:

  • high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) for heavy metals in saline groundwater
  • gas chromatography tandem mass spectroscopy (GC-MS/MS) for complex semi-volatile organic matrices
  • US EPA TO-15 canister methodology for airborne toxicants such as benzene, toluene and xylenes

NMI also helps laboratories maintain gas testing accuracy by offering proficiency testing schemes such as RGM 12-01 using a simulated unprocessed natural gas.

For further information please contact customerservice@measurement.gov.au, 1300 722 845 or use our on-line form

A selection of NMI’s environmental analyses applicable to CSG exploration and extraction

Water quality parameters for aquifer baseline, source, operational and verification monitoring (as specified by Queensland’s Department of Energy and Water Supply)
Physico-chemical parameters
pH, total dissolved solids (TDS), suspended solids (SS), electrical conductivity (EC — a measure of salinity)
Major ions (typically)
sodium, potassium, calcium, magnesium, chloride, sulphate, alkalinity (hydroxide, carbonate, bicarbonate), total hardness, ionic balance
Other
sodium adsorption ratio (SAR) calculated from above major cations, silicates
Hydrocarbons and related by-products
light hydrocarbons methane, ethane, propane, butane, pentane;
total petroleum hydrocarbons C6–C9 and C10–C36;
polycyclic aromatic hydrocarbons (PAHs);
benzene, toluene, ethyl benzene, xylenes (BTEX); speciated phenols; bisphenol A; nonylphenol
Disinfection by-products
trihalomethanes, oxyhalides (bromate, chlorate chlorite), haloacetic acids (HAA), total organic halides (TOX subcontracted)
Inorganics: non-metals
cyanide, fluoride, nitrate-N, iodine
full list of 69 elements
Radionuclides
subcontracted to specialised laboratory
Isotopic ratios (by HR-ICP-MS)
strontium isotope ratio 87Sr/86Sr (±0.001)
Total suspended solids (TSS), turbidity, ultraviolet absorbance (UVA at 254, 272, 436 nm), total organic carbon (TOC), dissolved organic carbon (DOC), SUVA (UVA at 254 nm/DOC × 100), nitrite-N, sulphide
Detecting fraccing fluid in produced water and groundwater
Commonly used fraccing fluid products may contain more than 60 chemical compounds or mixtures — test parameters need to be selected based on the likely components in use and the chemical form present after dissolution in groundwater — NMI can provide guidance on test selection
Ambient air monitoring
Air toxics
benzene, toluene, xylene (total meta-, para- and ortho-xylene isomers)
Non-chlorinated VOC compounds by US EPA T0-15
propene, 1,3-butadiene, carbon disulphide, hexane, cyclohexane, benzene, heptane, toluene, ethylbenzene, meta-xylenes, para-xylenes, styrene, ortho-xylene, 4-ethyltoluene
AS/NZS 3580.10.1:2003 filter testing
Workplace atmosphere — inhalable dust
AS 3640:2009 (sampling duration in excess of 60 min) filter testing
Light hydrocarbons
methane, ethane, propane, butane, pentane