COMPARISONS OF AUTOUGH2 AND WAIWERA ON GEOTHERMAL FIELDS

Abstract

One of the main constraints of geothermal reservoir model development is the time it takes to calibrate geothermal models. Model calibration requires running the model for each change in parameters made to improve the match to available data. In recent years,
Waiwera, a parallelised geothermal simulator, has been under development with the aim of speeding up geothermal model runs. While drawing on our experience with AUTOUGH2 (a serial geothermal simulator), Waiwera exploits parallelisation and has been
coded with better underlying numerics, which means the speed-up achieved is very significant.
Previously, we presented benchmark comparisons between AUTOUGH2 and Waiwera. Here we offer comparisons on models of real geothermal fields, both in terms of results and run-time. We now use Waiwera in most commercial and research projects, including
Lihir, San Jacinto, Ohaaki, Wairakei, Monserrat and Rotorua. With certain settings, when run on 40 cores, we see a speed-up of up to sixty times, meaning a model that took seven hours to run on AUTOUGH2 now takes seven minutes to run on Waiwera. This
speed-up has four main advantages: model calibration is faster, more refined grids can be used, larger systems can be modelled such as the whole of the Taupo Volcanic Zone and uncertainty quantification of model forecasts is more efficient. AUTOUGH2 and
Waiwera results for the simulation of a synthetic high enthalpy geothermal system are presented alongside those for a model of the San Jacinto geothermal field in Nicaragua developed by Polaris Energy Nicaragua S.A..