The Geoscience Australia (GA) building located in Symonston, ACT utilises one of the largest GSHP systems in the southern hemisphere. It is based on a series of 210 geothermal heat pumps throughout the general office area of the building, which carry water through loops of pipe buried in 352 bore holes each 100 metres deep and 20cm in diameter. The system is one of the largest and longest operating of its type in Australia, providing an opportunity to examine the long term performance of a GSHP system. A 10-year building review conducted in 2007 estimated that the system had saved about $400,000 in electricity costs. When comparing energy performance in the annual 'Energy Use in the Australian Government Operations' reports, the GA building has maintained energy performance and targets that might normally be expected of a general office administration building. This is significant given the requirements to provide additional fresh air to laboratories and 24/7 temperature control to special storage areas. The energy savings can be attributed to the GSHP system and other energy efficient design principles used in the building.

A regional seismic survey in north Queensland, with acquisition paremeters set for deep crustal imaging, show a potential geothermal target beneath about 2 km of sediments. Beneath the sedimentary structure there appears to be an area of low seismic reflection signal from about 1 s to 4 s. Combined with the relatively low gravity signature over this location, this area of low seismic reflection signal could be interpreted as a large granite body, overlain by sediments. This body lies near an area of high crustal temperature and suggests a potential geothermal energy target.

Geoscience Australia's $58.9M 5-year Onshore Energy Security Program began in 2006 and includes a new Geothermal Energy Project. The Project aims to assist in the development of a geothermal industry in Australia by: providing precompetitive geoscience information, including acquisition of new data; informing the public and government about Australia's geothermal potential; and partnering with industry in international promotional events for the purpose of attracting investment. This abstract gives a brief summation of activities undertaken by Geoscience Australia within the Onshore Energy Security Program, principally those of the Geothermal Energy Project.

Like many of the basins along Australia's eastern seaboard, there is currently only a limited understanding of the geothermal energy potential of the New South Wales extent of the Clarence-Moreton Basin. To date, no study has examined the existing geological information available to produce an estimate of subsurface temperatures throughout the region. Forward modelling of a basin structure using its expected thermal properties is the process generally used in geothermal studies to estimate temperatures at depth in the Earth's crust. This process has been validated for one-dimensional models such as a drill hole, where extensive information can be provided for a specific location. The process has also seen increasing use in more complex three-dimensional (3D) models, including in areas of sparse data. The overall uncertainties of 3D models, including the influence of the broad assumptions required to undertake them, are generally only poorly examined by their authors and sometimes completely ignored. New methods are presented in this study which will allow estimates and uncertainties to be addressed in a quantitative and justifiable way. Specifically, this study applies Monte Carlo Analysis to constrain uncertainties through random sampling of statistically congruent populations. Particular focus has been placed on the uncertainty in assigning thermal conductivity values to complex and spatially extensive geological formations using only limited data. These geological formations will typically consist of a range of lithological compositions, resulting in a range of spatially variable thermal conductivity values. As a case study these new methods are then applied to the New South Wales extent of the Clarence-Moreton Basin. The structure of the basin has been built using Intrepid Geophysics' 3D GeoModeller software package using data from existing petroleum drill holes, surface mapping and information derived from the FrOGTech SEEBASE study. A range of possible lithological compositions was determined for each of the major geological layers through application of compositional data analysis, using data from deep wells only (>2000 m). In turn, a range of possible thermal properties was determined from rock samples held by the New South Wales Department of Primary Industries and analysed at the Geoscience Australia laboratories. These populations of values were then randomly sampled to create 120 different forward models which were computed using SHEMAT. The results of these have been interpreted to present the best estimate of the expected subsurface temperatures of the basin, and their uncertainties, given the current state of knowledge. These results suggest that the Clarence-Moreton Basin has a moderate geothermal energy potential within an economic drilling depth. The results also show a significant degree of variability between the different thermal modelling runs, which is likely due to the limited data available for the region.

Preliminary compilation of data in the onshore Carptentaria Basin, Northern Territory. This basin, previously named the Dunmarra Basin, is poorly understood. This Record details the compilation of data in 3D for the basin. Data included are surface geological mapping, drillholes, gravity, magnetic, radiometric, visible LANDSAT, seismic reflection and digital elevation data.

A 3D map of the Cooper Basin region has been produced over an area of 300 x 450 km to a depth of 20 km (Figure 1). The 3D map was constructed from 3D inversions of gravity data using geological data to constrain the inversions. It delineates regions of low density within the basement of the Cooper/Eromanga Basins that are inferred to be granitic bodies. This interpretation is supported by a spatial correlation between the modelled bodies and known granite occurrences. The 3D map, which also delineates the 3D geometries of the Cooper and Eromanga Basins, therefore incorporates both potential heat sources and thermally insulating cover, key elements in locating a geothermal play. This study was conducted as part of Geoscience Australia's Onshore Energy Security Program, Geothermal Energy Project. This 3D data release constitutes the first version of the Cooper Basin region 3D map. A future data release (version 2 of the 3D map) will extend the area to the north and east to encompass the entire Queensland extension of the Cooper Basin. The version 2 3D map will incorporate more detailed 3D models of the Cooper and Eromanga Basins by delineating the major internal sedimentary sequences within the basins. Thermal properties will then be incorporated into the 3D map to produce a 3D thermal model. The goal is to produce a 3D thermal model of the Cooper Basin region that not only matches existing temperature and heat flow data in the region, but also predicts regions of high heat flow and elevated temperatures in regions where no heat flow or temperature data exists.

Within the Central Australian region, nominally constrained by 22.5oS 134oE and 31.5oS 144oE for this study, lie several systems of stacked basins beneath the extensive Mesozoic Eromanga Basin. Remnants of Proterozoic basins are largely inferred from gravity, unexplored, and are not everywhere differentiated from an extensive cover of the lower Palaeozoic Warburton Formation. This sequence is the central link between the contiguous Amadeus, Officer and Georgina Basins, and the Thomson Fold Belt. Since the Carboniferous, the region has largely experienced intracratonic sag and has accumulated continental sediments, including thick coal measures, with intermittent tectonism and uplift. In late Early Cretaceous, marine conditions briefly invaded this subsiding region, but continental sedimentation resumed in the Late Cretaceous. Tectonism occurred in the Tertiary with basin inversion and subsequent formation of the Great Artesian Basin. In the Cainozoic, the region is again in subsidence and accommodating fluvial and aeolian sediment slowly into the Eyre Basin. The preserved depocentres of the Carboniferous-Permian-Triassic Cooper, Pedirka-Simpson, and Galilee Basins are spatially separate, although all contain comparable, largely organically-mature continental coal measure sequences.

This volume is a compilation of Extended Abstracts presented at the 2010 Australian Geothermal Energy Conference, 17-19 November 2010, Adelaide Convention Centre, Adelaide, organised by the Australian Geothermal Energy Association and the Australian Geothermal Energy Group.

Exploration models for Rot Rock geothermal energy plays in Australia are based primarily on high-heat producing granites (HHPG) in combination with overlying low-conductivity sedimentary rocks providing the insulator necessary to accumulate elevated temperatures at unusually shallow (therefore accessible) depths. Unknowns in this style of geothermal play include the composition and geometry of the HHPG and thermal properties, and the thickness of the overlying sediments. A series of 3D geological models have been constructed to investigate the range of geometries and compositions that may give rise to prospective Hot Rock geothermal energy plays. A 3D geological map of the Cooper Basin region which contains known HHPG beneath thick sedimentary sequences, has been constructed from gravity inversions and constrained by geological data. The inversion models delineate regions of low density within the basement that are inferred to be granitic bodies. Thermal forward modelling was carried out by incorporating measured and estimated thermal properties to the mapped lithologies. An enhancement of the GeoModeller software is to allow the input thermal properties to be specified as distribution functions. Multiple thermal simulations using Monte-Carlo methods would be carried out from the supplied distributions. Statistical methods will be used to yield the probability estimates of the in-situ heat resource, reducing the risk of exploring for heat. The two thermal modelling techniques can be used as a predictive tool in regions where little or no temperature and geological data are available.

The Geoscience Australia (GA) building located in Symonston, ACT utilises one of the largest GSHP systems in the southern hemisphere. It is based on a series of 210 geothermal heat pumps throughout the general office area of the building, which carry water through loops of pipe buried in 352 bore holes each 100 metres deep and 20cm in diameter. The system is one of the largest and longest operating of its type in Australia, providing an opportunity to examine the long term performance of a GSHP system. A 10-year building review conducted in 2007 estimated that the system had saved about $400,000 in electricity costs. When comparing energy performance in the annual 'Energy Use in the Australian Government Operations' reports, the GA building has maintained energy performance and targets that might normally be expected of a general office administration building. This is significant given the requirements to provide additional fresh air to laboratories and 24/7 temperature control to special storage areas. The energy savings can be attributed to the GSHP system and other energy efficient design principles used in the building.