Technology:

Geothermal Reservoir Model Goes Back to Basics (Science Network Western Australia)

(Courtesy Lionel Estebana, et al)

Commonwealth Scientific and Industrial Research Organisation (CSIRO) researchers have developed the first-ever model for predicting the thermal conductivity of sandstones from deep wells in geothermal reservoirs.

As opposed to more complex existing models, this model's strength is that scientists only need the measurements of porosity and P-wave velocity (the speed of ultrasonic sounds for the rocks), which could be easily estimated or measured from rock samples in the laboratory.

CSIRO petrophysicist and lead author Dr Lionel Esteban says measurements of temperature, thermal conductivity and water flow are required to predict the heat flow (amount of extractable heat) from geothermal reservoirs.

The thermal conductivity of rocks—which controls how well they trap the generated heat—is one of the key factors required to predict heat flow, Dr Esteban says.

"While the flow of water and temperature can be measured using a probe, assessing the thermal conductivity of rocks in-situ [directly in deep wells or boreholes] is currently impossible."

"Models that are currently available in the market to predict thermal conductivity also require a large amount of parameters and are difficult to use in practical applications."

Study cases of thermal conductivity prediction from P-wave velocity and porosity - Geothermics, Volume 53, January 2015, Pages 255–269

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