Petrophysical Characterisation in Geothermal Reservoirs: What For?

Abstract

The rocks found in geothermal systems are widely heterogeneous and complex, yet they need to be represented numerically so that the features of the system can be modelled and the system’s behaviour simulated to achieve optimal field management.
Geological parameters conventionally used to classify rocks for geological models, e.g., lithology or origin, seldom provide numerical data related to their physical properties. These data are required as inputs for numerical reservoir models, so it is important to strengthen the petrophysical characterisation workflow so more rock-based numerical data can be provided to the models.
This paper overviews a petrophysical characterisation technique based on textural features and presents it as a tool for the geothermal fields of New Zealand. We show how this technique may be used to estimate petrophysical values of reservoir and seal rocks based on observed features by using examples of rock types from the Tauhara Geothermal Field of New Zealand.