PERSPECTIVES ON GEOTHERMAL PERMEABILITY

Abstract

How does a geologist’s concept of permeability differ from that of a reservoir engineer? Permeability is a fundamental question in geothermal resource development, but it’s typically discussed through jargon that varies between these two groups of specialists. This paper explores the parameterization of permeability from both perspectives and shows that a combined approach supported by careful observation, data analysis and modeling is more likely to accurately characterize the subsurface by increasing the breadth of observed data and reducing bias. Core concepts such as porosity, fracture volume, fracture spacing will be discussed. The paper uses conceptual, visual and numerical examples from three Taupo Volcanic Zone geothermal systems, including a recently developed geothermal system where the strategic acquisition of high quality resource data has shed new light on the nature of permeability.