Synthetic thermal modelling, constrained by available geological and geophysical datasets, is used to aid in geothermal target identi9fication and prioritization

This volume is a compilation of Extended Abstracts presented at the 2008 Australian Geothermal Energy Conference, 19-22 August 2008, Rydges Hotel, Melbourne, organised by the Australian Geothermal Energy Association and the Australian Geothermal Energy Group. This Conference is the first dedicated conference organised by the geothermal energy community in Australia and has been made possible by the seed funding from the Australian Government under the Sir Mark Oliphant Conference funding scheme with additional sponsorship of the companies acknowledged earlier and paying delegates. This Conference is being held at a time of rapid growth in all sectors of the geothermal community. The number of companies engaged in exploration stands at 33, the number of leases held or applied for is 320, and the value of the work program for these companies exceeds $850 million between 2002-2013. The Australian Geothermal Energy Association has been incorporated to serve as the peak industry representative body. The Universities of Queensland, West Australia, Adelaide and Newcastle have new funding specifically for geothermal research programs. The Australian Government has continued its strong support of the sector through the Geothermal Industry Development Framework and Technology Roadmap, the Geothermal Drilling Program, and the Onshore Energy Security Program. All of the States now have legislation regulating geothermal exploration activity in place, and the Northern Territory has drafted legislation for presentation to parliament. This volume of Extended Abstracts starts with a summary snapshot of the global and national geothermal energy sectors. The rest of the volume is organised under three headings: Underground Science and Technology Power Conversion Technologies Legislation, Policy and Infrastructure

This is a paper submitted for the 29th NZ Geothermal Workshop, presenting information about the geothermal industy in Australia, the impediements the industry faces and Geoscience Australia's role in reducing the geoscience-related impediments. Paper abstract is as follows: Australia's emergent geothermal energy industry is growing rapidly, with 29 geothermal companies currently prospecting for Hot Rock and hydrothermal resources. The Hot Rock model in the Australian context comprises a thick sequence (>3km) of low-thermal conductivity sediments overlying deeper high-heat-producing granites. Until now, the key datasets available to industry to guide their geothermal exploration have been a map of crustal temperature at 5km depth, and heat-flow data. Both datasets suffer from regions of low data density and heterogeneous data distribution. The Australian Government has provided Geoscience Australia with funding for an Onshore Energy Security Program (OESP). Established as part of the OESP, a new Geothermal Project will generate precompetitive geoscientific information for geothermal explorers through two major activities: mapping heat across Australia, and developing a geothermal information system. The Australian Government has also awarded several renewable energy and start-up grants to the geothermal industry since 2000, and is currently funding the preparation of a Geothermal Industry Development Framework (GIDF). The GIDF aims to support the industry by developing strategies to ensure that technical, economic and regulatory obstacles are tackled in a coordinated way.

Australia's hot rock and hydrothermal resources have the potential to fuel competitively-priced, emission free, renewable baseload power for centuries to come. This potential and the risks posed by climate change are stimulating geothermal energy exploration projects in Australia. Extracting just 1 percent of the estimated energy from rocks hotter than 150°C and shallower than 5,000m would yield ~190 million PJ or about 26,000 times Australia's primary power usage in 2005. This figure does not take into account the renewable characteristics of hot rock, nor the resource below 5,000m. To year-end 2007, thirty-three companies have joined the hunt for geothermal energy resources in 277 licence application areas covering more than 219,000 km2 in Australia. Companies are targeting resources that fall into two categories: (1) hydrothermal resources in relatively hot sedimentary basins; and (2) hot rocks. Most exploration efforts are currently focused on hot rocks to develop Enhanced Geothermal Systems (EGS) to fuel binary power plants. Roughly 80 percent of these projects are located in South Australia. The basic geologic factors that limit the extent of hot rock plays can be generalised as: - source rocks in the form of radiogenic, high heat-flow basement rocks; - traps defined by favourable juxtaposition of low (thermal) conductivity insulating rocks to radiogenic heat producing basement rocks; - heat-exchange reservoirs under favourable stress conditions within insulating and basement rocks; and - a practical depth-range limited by drilling and completion technologies (defining a base) and necessary heat exchange efficiency (defining a top). A considerable investment (US$200+ million) is required to prove a sustainable hot rock play, and demonstrate the reliability, scalability and efficiency of EGS power production. The proof-of-concept phase entails the drilling of at least two deep (>3,500m) hot holes (one producer and one injector), fracture stimulation, geofluid flow and reinjection and heat exchange for power generation. Compelling demonstration projects will entail up-scaling, including smooth operations while drilling and completing additional Hot Rock production and injection wells and sustained power production, most probably from binary geothermal power plants. Australian government grants have focused on reducing critical, sector-wide uncertainties and equate to roughly 25% of the cost of the private sector's field efforts to date. A national hot rock resource assessment and a road-map for the commercialisation of Australian hot rock plays will be published in 2008 by the Australia federal government. Play and portfolio assessment methods currently used to manage the uncertainties in petroleum exploration can usefully be adapted to underpin decision-making by companies and governments seeking to respectively push and pull hot rock energy supplies into markets. This paper describes the geology, challenges, investment risk assessment and promising future for hot rock geothermal energy projects in Australia.

Geoscience Australia's Geothermal Energy Project is part of the Energy Security Initiative announced by the Prime Minister in August 2006. Geoscience Australia received $58.9 million over five years to implement the Onshore Energy Security Program by acquiring new data to attract investment in exploration for onshore petroleum, geothermal, uranium and thorium energy sources. The Program will acquire national-scale geophysical and geochemical data, including seismic, gravity, heat flow, radiometric, magneto-telluric and airborne electromagnetic data in collaboration with the state and Northern Territory governments under the National Geoscience Agreement. Formulating the Geothermal Energy Project The key geological ingredients of the "hot rock" geothermal model are high heat-producing granites overlain by thick accumulations of low thermal-conductivity sediments. The decay of low concentrations of radiogenic elements (mostly uranium, thorium and potassium) over millions of years produces heat in the granite. This heat may be trapped at depth within the crust by a sedimentary cover that lies above the granite like a blanket. Where temperatures are high, water circulating through the hot rocks can be used to generate electricity. At lower temperatures, the heat can be used for indirect use applications, such as space and water heating. By raising awareness of Australia's geothermal potential among decision-makers and the general public, the Geothermal Energy Project aims to support development of a geothermal energy industry by encouraging investor confidence. Extensive consultation with state and Northern Territory geological surveys and geothermal exploration companies has identified a list of key impediments faced by geothermal explorers. The project aims to reduce those impediments through geoscience input. The greatest identified geoscience need is for a better understanding of the distribution of temperature in the continent's upper crust. Two existing datasets the Austherm05 map of temperature at five kilometres depth, and a database of heat flow measurements suffer from having too few data points, compounded by poor distribution. Geoscience Australia aims to provide additional information for both datasets. A third way to predict heat distribution is to use geological modelling of high heat-producing granite locations and overlying low thermal-conductivity sediments. Other geoscience inputs to be developed to improve discovery rates and reduce risk for explorers include: -a comprehensive and accessible geothermal geoscience information system -an improved understanding of the stress state of the Australian crust -increased access to seismic monitors during reservoir stimulation -a reserve and resource definition scheme.

An extension of previously developed methods to calculate in-situ 3D temperature directly from 3D geology models in 3D GeoModeller software now allows for quantification of the uncertainty associated with those calculations. This work is being collaboratively undertaken by Intrepid Geophysics and Geoscience Australia, and will offer Australia's geothermal industry both: i) a new predictive tool helping to reduce the risk of Enhanced Geothermal System (EGS) exploration and heat resource estimation, and ii) stochastic temperature and heat flow maps of Australia.

The hot rock geothermal model in the Australian context comprises high-heat producing granites overlain by thick accumulations of low-thermal conductivity sediments. The granites have low concentrations of radiogenic elements, and over hundreds of millions of years, these elements decay and produce heat. The passage of this heat to the Earth's surface via upwards conduction is slowed by layers of sediments that have low thermal conductivity, creating 'hot spots' beneath the blankets. This thematic map shows granites attributed by heat production and basin depth. The majority of the granites depicted are of surface outcrop. The presence of high-heat producing granites adjacent to deep sedimentary basins may be used as a first-order indicator of where to further investigate the possibility of hot rock geothermal plays. The main frame of the map shows all granites (attributed by calculated heat production - where available), sedimentary basins (and their order e.g. where one basin is overlapped by another) and geothermal licences and applications. The top right inset map shows only those granites with a calculated radiogenic heat generation of >5 uW -3, with the depth of the sedimentary basins. This map provides a rapid view of areas that may be expected to have the greatest hot rock potential. The second-from-top inset map shows all suitable geochemical analyses from OZCHEM, attributed by calculated radiogenic heat generation. This shows both the distribution of data that goes into attributing the granite polygons, and also analyses of granites (and other rocks) that fall outside the mapped granite polygons that are otherwise excluded from the main map. The third-from-top inset map shows the distribution of drillholes with temperature measurements. The bottom inset map shows an image of the Austherm07 database, which is derived from the drillhole temperature information. The image shows the projected temperature of the crust at a depth of 5 kilometres, interpolated between the drillholes. Overlain on this image is the small number of publicly-available heat flow data.

This is a 3 minute movie (with production music), to be played in the background during the October 28th 2010 Geoscience Australia Parlimentary Breakfast. The video shows a wide range of the types of activities that GA is involved in. These images include GA people doing GA activities as well as some of the results of offshore surveys; continental mapping; eath monitoring etc. The movie will be played as a background before and after GA's CEO (Chris Pigram) presentation.

The hot rock geothermal model in the Australian context comprises high-heat producing granites overlain by thick accumulations of low-thermal conductivity sediments. The granites have low concentrations of radiogenic elements, and over hundreds of millions of years, these elements decay and produce heat. The passage of this heat to the Earth's surface via upwards conduction is slowed by layers of sediments that have low thermal conductivity, creating "hot spots" beneath the blankets. This thematic map shows granites attributed by heat production and basin depth. The majority of the granites depicted are of surface outcrop. The presence of high-heat producing granites adjacent to deep sedimentary basins may be used as a first-order indicator of where to further investigate the possibility of hot rock geothermal plays. The main frame of the map shows all granites (attributed by calculated heat production where available), sedimentary basins and their order (e.g. where one basin is overlapped by another) and geothermal licenses and applications. The top right inset map shows only those granites with a calculated radiogenic heat generation of >5 Wm-3, and the depths of the sedimentary basins. This map provides a rapid view of areas that may be expected to have the greatest hot rock potential. The second-from-top inset map shows all suitable geochemical analyses from OZCHEM, attributed by calculated radiogenic heat generation. This shows both the distribution of data that goes into attributing the granite polygons, and also analyses of granites (and other rocks) that fall outside the mapped granite polygons and are otherwise excluded from the main map. The third-from-top inset map shows the distribution of drillholes that have temperature measurements. The bottom inset map shows an image of the Austherm07 database, which is derived from the drillhole temperature information. The image shows the projected temperature of the crust at a depth of 5km, interpolated between the drillholes. Overlain on this image is the small number of publicly-available heat flow data. This map is GA GeoCat record 65306. ISBN (print): 978-1-921236-44-0; ISBN (web): 978-1-921236-45-7. Webpage: http://www.ga.gov.au/minerals/research/national/geothermal/index.jsp.

Australia's emergent geothermal energy industry is growing rapidly. So far, 29 companies have applied for geothermal exploration licenses. The majority of these companies are prospecting for Hot Rock geothermal resources for electricity generation, with some companies targeting hydrothermal resources. The Hot Rock model in the Australian context comprises a thick sequence (>3km) of low-thermal conductivity sediments overlying deeper high-heat-producing granites. Until now, the key dataset available to industry to guide their geothermal exploration has been a map of crustal temperature at 5km depth1. Compiled from temperature measurements made in 5,722 petroleum wells across Australia, the map indicates a vast geothermal resource. Additional national-scale geothermal datasets are either incomplete, not publicly accessible, or have not been collected. In August 2006, the Australian Government announced an Energy Security Initiative. It provides $58.9M to Geoscience Australia (the national geoscience and spatial information agency) over five years for an Onshore Energy Security Program (OESP). The OESP aims to better understand Australia's geological potential for onshore energy resources such as petroleum, uranium and geothermal, and includes the acquisition of new seismic, radiometric, heat-flow, magneto-telluric, gravity, magnetic, geochemical and drill-hole data. Providing new data will help attract company exploration in new areas by enhancing the chances of discovery and reducing the risks to investors. Established as part of the OESP, a new Geothermal Energy Project will generate precompetitive geoscientific information for geothermal explorers through two major activities: creating maps of heat distribution across Australia, and developing a geothermal information system. Heat distribution will be mapped in three ways: (1) new heat flow measurements in existing and new drill-holes; (2) a granite source-sediment heat trap map to identify Hot Rock systems; and (3) enhancements to the 5km-temperature-map method of Chopra and Holgate1. The geothermal information system will include thermal conductivity, thermal gradient, geochemistry, density, and heat production amongst other data types. The Australian Government is also facilitating and funding the preparation of a Geothermal Industry Development Framework, which is being lead by the Department of Industry, Tourism and Resources. The Development Framework aims to support the growth of Australia's geothermal industry by identifying opportunities and impediments to the industry's growth, and developing strategies to ensure that technical, economic and regulatory obstacles are tackled in a coordinated way. 1 Chopra, P. and Holgate, F., (2005) A GIS analysis of temperature in the Australian crust, Proceedings of the World Geothermal Congress 2005, Antalya, Turkey, 24-29 April 2005.