Geothermal Energy Potential in Selected Areas of Western Australia ...

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4.5. Rock thermal conductivity measurement
Thermal conductivity is the physical property that controls the rate at which heat
energy flows through a material
in a given thermal gradient. In the S.I. system of
units, it is measured in watts per metre-Kelvin (W/mK). In the earth, thermal
conductivity controls the rate at which temperature increases with depth for a given
heat flow. The thermal conductivity distribution within a section of crust must be
known in order to calculate crustal heat flow from temperature gradient data, or to
predict temperature distribution from a given heat flow.
Steady-state thermal conductivity measurements were undertaken by HDRPL for 36
representative samples from lithologies of the Perth Basin using HDRPL’s portable
divided bar thermal conductivity apparatus. The full conductivity report is provided in
Appendix-1 and a summary of measurements is provided in Attachment E.
Rock thermal conductivity is highly dependent upon lithology, so some modifications
to the measured data are required to ensure that conductivity data utilised in the 1D
heat flow models best represent the typical lithologies found within the basin. A
process of weighted thermal conductivity calculation was undertaken based on
various lithology mixes as described on well logs. This process is described by
Beardsmore and Cull (2001) 9 and a summary of the calculation inputs is provided in
Attachments F and G.
The final rock thermal conductivity values, as used in the 1D heat flow models for the
southern and northern Perth Basin, are shown in Tables 4.1 and 4.2.
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