(471e) A Coupled Wellbore-Reservoir Numerical Simulator and Its Integration with Techno-Economic Model Geophires for Enhanced Geothermal Systems

In response to the growing energy demand and fast depletion of fossil fuels, the exploration of alternative energy sources has been increased in last few decades. Among these sources, geothermal energy is considered as a clean and reliable with abundant reserves worldwide. Recent advances in geothermal technology allow us to create an artificial reservoir by hydraulic stimulation called enhanced geothermal systems (EGS), which are not limited to tectonically active areas, but can be created anywhere in the world up to the depths of 10 km. In order to predict the production potential and economic feasibility of an EGS system, numerical modeling of the three major components (wellbore, reservoir, and the surface plant design and economics) is required. Integrating these components together into a single techno-economic model allows optimization of the operating parameters and reduction in total simulation time.

In this work, a combined model for EGS is developed by integrating coupled wellbore-reservoir numerical model with the existing techno-economic (GEOPHIRES) model. First, an unsteady state one-dimensional numerical wellbore simulator is developed for modeling single-phase water flow and heat transfer in the injection and production wellbores, which is then sequentially coupled with a numerical reservoir model (TOUGH2-EGS). The coupled wellbore-reservoir model is added to the GEOPHIRES as a new option to the already existing four analytical reservoir models. The application of the combined model is demonstrated for electricity generation and direct-use heat in Morgantown, West Virginia using EGS system. The levelized cost of electricity and direct-use heat are found to be very high (compared to other energy sources, e.g. natural gas, coal etc.) owing to the low-grade quality of the thermal resource. The results comparison between GEOPHIRES existing analytical model and the new combined model emphasized the need of the coupled numerical wellbore-reservoir model for more realistic representation and accurate evaluation of production potential and economic feasibility of the EGS system.