Coastal Geothermal Energy Initiative

The Queensland Government has committed $5million for the Coastal Geothermal Energy Initiative (CGEI) to define regions with high geothermal heat flow which may indicate new sources of geothermal energy along the Queensland coast, close to existing electricity transmission lines. The CGEI is a joint undertaking between the Office of Clean Energy and the Geological Survey of Queensland.

Objectives

• Identify areas in eastern Queensland where additional heat flow and temperature data is required
• Collect new data by drilling specific wells and through liaison with industry
• Improve geophysical coverage of coastal areas where required
• Provide an assessment of geothermal resource potential in eastern Queensland

Potential geothermal targets have been identified based upon an understanding of the geology and tectonic history of eastern Queensland. These areas are considered to have the potential for hot rocks to be present where elevated heat-flow conditions may exist. No specific geothermal-energy model has been applied to their selection.

Rationale

• History of high heat-flow conditions
• Existing high geothermal gradients
• Extrapolated buried high-heat producing granite under insulating sedimentary cover
• Inferred buried granitoids from geophysical anomalies
• Radiogenic volcanics and granites
• Recent volcanism
• Sedimentary basins with insulating sequences such as coal and oil shale

A thorough geological assessment will be undertaken for each geothermal target to determine eligibility to be drilled based on available geological and geophysical data. Potential targets covered by a granted or application for a Geothermal Exploration Permitor Geothermal Land Release tender area will be selected to be tested for drilling under this initiative.

The drilling program is anticipated to begin in early 2010 and will include:

• Fully cored holes from surface to total depth of 300-320m
• Temperature and additional petrophysical data from down-hole logging
• Well log interpretation and core logging
• Collection of core samples for analysis of thermal conductivity parameters

Geoscience Australia will provide technical support through laboratory analysis and down-hole logging. Temperature measurements and thermal conductivity measurements will be used to calculate heat-flow. Additional geophysical data may be acquired over target areas and will be determined from the drilling results.

Outcomes

• Increase geothermal exploration opportunities in eastern Queensland
• Provide an updated database of temperature and heat flow measurements
• Develop maps showing heat anomalies in eastern Queensland
• Report on the geothermal potential of eastern Queensland
• Provide the background data for industry to identify potential targets for geothermal energy in eastern Queensland
• Decrease risk to explorers