Water Journal : Water Journal August 2013
AUGUST 2013 WATER 47 Conference Report Ethyl benzene was typically one or two orders of magnitude below the long term ESL (ESL is the Effects Screening Levels and the screening levels used in TCEQ's air permitting process to evaluate air dispersion modelling predicted impacts. They are used to evaluate the potential for effects to occur as a result of exposure to concentrations of constituents in the air). Health hazards associated with shale gas typically occur via two pathways, waterborne and airborne. Dr Duncan discussed levels of risk and quoted William W Lowrance, author of a 1976 book called Acceptable Risk. Lowrance states that "because nothing can be absolutely free of risk, nothing can be absolutely safe". Dr Duncan has researched the levels of risk associated with risk well leakage. The leakage rate for Class 1 injection wells is estimated to be 1 x 10-8 and the estimated rate of subsurface blowouts of shale gas wells is 2to4x10-6. However, most of the environmental incidents that have occurred since then have been found to have been caused by operator or human error rather than the engineering of the extraction process. This is a valuable take-home message for the Australian experience, according to Dr Duncan. The second keynote speaker for all four seminars was Dr Peter Flood. He offered an Australian context to the unconventional gas market in Australia, recognising that there were many opportunities and challenges in this country. The opportunities for coal seam gas are mainly in Queensland in the Surat Basin, and for shale gas in the Canning Basin in Western Australia and the Cooper Basin in South Australia. Some of the perceived issues for this emerging gas industry include environmental concerns about the contamination of water from the 'fraccing' process (hydraulic fracturing); social concerns from landowners seeking the right to restrict gas company access to farmland from which gas can be extracted; and inconsistent and often changing regulatory frameworks at both a state and federal level, bring uncertainty to investment in the industry. Dr Flood gave a good explanation of the different geology types of the different sources of conventional and unconventional gases, as shown in Figure 2. He also gave a very concise explanation of the extraction process and the way that fraccing is conducted. In discussing Australia's gas reserves, Dr Flood advised that Australia has about two per cent of the world's gas reserves and approximately 2.1 per cent of the global production in 2010. He said that gas is Australia's third largest energy resource after coal and uranium. The table below gives an estimate of where the global coal seam gas reserves are located. Dr Flood also discussed issues of community concern and how the gas industry was responding to these concerns, which relate to blowout risk, casing failure, and issues relating to fraccing such as earthquakes and the escape of methane into aquifers. As Dr Duncan discussed, the risk related to blowout and casing failure can be demonstrated to be very low; however, other risks are still somewhat unknown and largely depend on the geology of the gas eld. What is clear from the Unconventional Gas Thought Leadership Seminar series is that there is a wealth of engineering and scienti c information that Australia can leverage from the United States and that more research needs to be done for the Australian context. During the panel session of the Canberra seminar, there was a good deal of discussion regarding policy interventions that create uncertainty in the industry. Interestingly, during the series an amendment to Australia's national environment law, the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), passed the senate and received Royal assent. The following information is from the Department of Sustainability, Employment, Water, Population and Communities regarding the amendments to the EPBC Act: 'This amendment to Australia's national environment law, the EPBC Act, makes water resources a matter of national environmental signi cance, in relation to coal seam gas and large coal mining development. This means that such developments will require federal assessment and approval to ensure the protection of water resources. Any coal seam gas and large coal developments that have a signi cant impact on any of the existing matters of national environmental signi cance, e.g. nationally threatened plants and animals, already have to be referred under the EPBC Act. Since 2012 these projects have been referred to the Independent Expert Scienti c Committee for advice on the impacts on water resources. The Minister takes this advice into consideration when making a nal decision. However, the Minister does not currently have the power to consider and impose conditions directly relating to impacts on a water resource itself. This amendment adds water as a trigger in its own right, and the Minister can set appropriate conditions as part of the project approval to ensure that any signi cant impacts on a water resource are acceptable. The amendment does not apply to shale gas. The amendments to the EPBC Act build on the objectives of the National Partnership Agreement on Coal Seam Gas and Large Coal Mining (NPA).' For more information please refer to www.environment.gov.au/ epbc/about/water-trigger.html#overview AWA and the National Centre for Groundwater Research and Training is holding a series of two-day short courses titled 'The Science: Coal Seam and Shale Gas', which will run in Perth on 12 August, Adelaide on 14 August and Brisbane on 16 August. To register please go to www.awa.asn.au/unconventionalgas/ Country Estimated CSG resource base (Trillion cubic metres) Canada 17--92 Russia 17--80 China 30--35 Australia 8--14 USA 4--11 Source: IEA CCC 2005 Conventional non-associated gas Land surface Tight sand gas Sandstone Gas-rich shale Seal Conventional associated gas Coalbed methane Figure 2. Different geological sources of conventional and unconventional gases.
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