monash_160292.pdf (5.82 MB)
Understanding environmental risks associated with unconventional gas development in Australia.
thesisposted on 2017-03-01, 02:08 authored by Drinkwater, Rowan Thomas
In light of the increasing demand for gas resources, both domestically and internationally, the Australian coal seam gas (CSG) industry has grown rapidly over the past decade. Despite, and in some ways due to, this rapid growth, the scientific understanding around some of the areas of environmental risk remains poorly documented. Alongside this growth has been an increase of both media and community attention and concern regarding what have been described by these groups as impacts related directly to the development of CSG in these regions. Despite this concern, industry groups have remained consistent in their conviction that these impacts can be monitored and managed on an ongoing basis. The literature review outlines the broad processes involved in CSG formation through to production, areas of associated environmental risks deemed significant including risks from surface infrastructure, groundwater depressurisation and depletion, changes in groundwater chemistry, contaminant migration pathways and mechanisms and a discussion around the implications of fugitive emissions from this industry. A broad description of the legislative and regulatory frameworks related to the CSG industry is presented, alongside some of the concerns regarding the appropriateness of this regulatory regime and approaches to evaluating these concerns. A review of methods which can be used to estimate gas fluxes from the soil is also presented. Overall this review highlights a number of gaps in knowledge, particularly around the mobilisation and transport of stray methane (CH4) within the hydrogeological system and surrounding atmosphere. Three lines of inquiry have been pursued in the attempt to contribute towards a better understanding of the environmental risks involved with the CSG developments in Queensland. Firstly, a review of available data related to CSG production is presented, which outlines the lithology and hydrogeological conceptual model developed using this primary data. Next, an evaluation of production data is presented, aimed at understanding magnitudes of risk associated with water and gas extraction regimes. This review highlights the need for better data transparency and changes in the magnitudes of water extraction since the early years of CSG developments. An evaluation of the regulation and environmental assessment is also presented, systematically reviewing the primary documents involved with the main CSG projects – Environmental Impact Statements, Environmental Authorities and Environmental Monitoring Reports. This review has highlighted a number of issues relating to the lack of data around CH4 movement, gaps in baseline and ongoing monitoring data requirements and issues relating to assumptions around magnitudes of risk that are questionable. Finally, a pilot scale study investigating the flux of CH4 from soil within the CSG development area was conducted. The study, aimed at assessing the viability of different methodologies in estimating soil fluxes as well as the presence of CH4 emissions from the soil. The results from this study highlight the complex nature of this topic of investigation as well as evidence to support the presence of positive soil fluxes within the CSG fields in Queensland. Overall, the thesis highlights issues with regards to data access, gaps in understanding related to specific areas of risk and presents data which questions some of the underlying assumptions around magnitudes of risk associated with CSG developments. Despite these issues, there is good evidence to suggest positive steps are being taken toward improving not only the data around understanding these areas of environmental risk, but also efforts contributing toward open access to data and transparent operations within the CSG fields.