Waiwera: A New Parallel Open-Source Geothermal Reservoir Simulator

Abstract

Waiwera is a new multi-phase subsurface flow simulator designed particularly for modelling geothermal reservoirs. Based around the PETSc library, it features scalable parallel execution on multi-core desktop machines and compute clusters, enabling large models to be run efficiently. Revised algorithms for handling multi-phase flows (particularly regarding the gravity term, and phase transitions), together with the advanced parallel linear solvers and preconditioners made available by PETSc, give improved performance for geothermal simulations, particularly the convergence of natural state models. A new flexible system for handling complex arrangements of source terms facilitates the modelling of geothermal steamfields. Waiwera also features a clearly structured object-oriented code-base, modern software development principles (e.g. unit testing), use of standardised efficient formats for input and output, and an open-source license. In this paper we describe the capabilities of Waiwera and demonstrate its performance on benchmark problems and real geothermal reservoir models.