Abstract:
Scanning Electron Microscopy (SEM) was used to examine the characteristics of micro-fractures and voids, their dimensions, quantity and connectivity, in core recovered from two geothermal fields, referred to as A and B, located in the Taupo Volcanic Zone, New Zealand. SEM observations revealed significant variation in void structure exists between (i) host rocks of the same lithologic unit, even over small depth intervals of <7 m, (ii) different lithologic units. In geothermal field A, void dimensions and micro-fracture connectivity increases with depth, while in geothermal field B, void dimensions and micro-fracture networks decrease with depth. The structure of voids control a rocks ability to transmit or store fluid, therefore it is important to understand site specific controls on permeability.
