Influence of Geological Structures on Fluid and Heat Flow Fields

Geothermal exploration is commonly performed in the absence of 3-D seismics or other high quality methods constraining the geometry of the underlying geological system. Therefore, uncertainty resides in the structural model itself. This is in addition to the usual assumption of stochasticity in the petrophysical properties. We show here that small changes in the geometrical description of the geology can produce large changes in the character of heat transport. Combining these sensitivities with the inherent uncertainties in geological model characterization, we suggest that the careful consideration of the systematics of geothermal heat transport is warranted. At present, these sensitivities are not widely recognized because the infrastructure to explore these links has not previously existed to the best of our knowledge. We have therefore constructed an integrated workflow that combines geological modeling directly with fluid and heat flow simulation. This allows us to calculate the heat transport variability in an ensemble approach. We apply our method to a geological model of the North Perth sedimentary basin in Western Australia. For interpretation of the results, we suggest a particularly useful analysis is the spatial variability of temperature fluctuations combined with the variability of the Peclet numbers in horizontal and vertical directions.