Geothermal data analysis and optimization

Abstract

The possibility of convective upwelling in the sedimentary Perth Basin, based on available data and simple models, was examined and its relative contribution to heat transport in a geothermal context assessed. The presence of such upwelling could greatly increase the viability of geothermal power extraction from the Basin. The onset of convection is determined by the Rayleigh number, which provides a measure for the balance between buoyancy driven upwelling and viscous resistance to flow. Being sedimentary, the porous aquifer system is layered and fractured so that the effects of anisotropy, especially that in permeability, need to be accounted for when determining the critical Rayleigh number. Variations in viscosity and the coefficient of thermal expansion also occur within the convection zone. Estimates were made for the relative size of the convective contribution to heat transport. The possibility of the surface detection of cellular convection and the effects of horizontal inflow into the convection zone were examined. References D. N. Smith, ``Cockburn No. 1 Well, Western Australia, Well Completion Report'', Western Australian Petroleum, Pty. Limited , October 1967. O. Kvernvold and P. A. Tyvand, ``Nonlinear thermal convection in anisotropic porous media'', J. Fluid Mech. , 90, pp.609--624, 1979. E. R. Lapwood, ``Convection of a fluid in a porous medium'', Proc. Camb. Phil. Soc. , 44, pp.508--521, 1948. R. McKibbin, ``Convection in an aquifer above a layer of heated impermeable bedrock'', NZ J. Sci., 26, pp.49--64, 1983. R. McKibbin, ``Thermal convection in layered and anisotropic porous media: a review'', In: Wooding, R. A. and I. White, (eds) ``Convective Flows in Porous Media'', Dept. Sci. Indust. Res., Wellington, New Zealand, pp.113--127, 1985. R. McKibbin, N. Hale, R. W. Style, and N. Walters, ``Convection and heat transport in layered sloping warm-water aquifers'', Journal of Porous Media, In press. D. A. Nield and A. Bejan, Convection in porous media , 3rd Edition, Springer, 2006. R. C. Ransom, Practical formation evaluation , Wiley, 1995. K. Regenauer-Lieb, H. T. Chua, X. Wang, F. G. Horowitz and J. Wellman, ``Direct heat geothermal applications in the Perth Basin of Western Australia'', Proc. 34th Annual Stanford Workshop on Geothermal Engineering , Chapter 14, Stanford University, California, 2009.