INTRODUCING THE VOLSUNG GEOTHERMAL SIMULATOR: BENCHMARKING AND PERFORMANCE

Abstract

In this paper we introduce the Volsung Geothermal Reservoir Simulator software package. At its core is a very fast numerical reservoir simulator based on the finite volume method (FVM). Its computational backbone is based on a hybrid method, where most of the numerically intensive calculations are performed on a CPU and only the memory bandwidth-limited linear solve operations are outsourced to an inexpensive, consumer-grade graphical processing unit (GPU). This approach enables vast performance enhancements when compared with traditional CPU-based systems while avoiding the hardware and software complexity of distributed memory architectures found in other high-performance-computing solutions.
We have validated Volsung versus test models from the Stanford 1980 Geothermal Model Intercomparison Study. In addition, we created simple test models to compare Volsung to results from the TOUGH2 simulator for selected problems of interest. Tests include a dual-porosity simulation problem which uses the Multiple Interacting Nested Continua (MINC) formulation, simulations using different equations of state (water, non-condensible gas and salt) and simulation runtime comparison. In all cases Volsung successfully reproduced the expected model results and achieved large speedups versus TOUGH2 for production size models.