Incorporating Complex Three-Dimensional Fracture Networks into Geothermal Reservoir Simulation

Abstract

This work develops a new approach for generating stochastic permeability fields from complex three-dimensional fracture networks to support physical and economic performance analyses of enhanced geothermal systems (EGS). The approach represents multiple fracture sets with different dips, orientations, apertures, spacing, and lengths by homogenizing discrete fracture permeabilities onto a regular grid using continuum methods. A previously developed algorithm is used for combining multiple fracture sets at arbitrary orientations into a full anisotropic permeability tensor for every grid block. Fracture properties for each grid cell can either be independently specified or spatially correlated using a variety of probability distributions. The generated stochastic permeability fields are used in mass and heat transport models to represent a variety of complex fracture networks to provide realistic simulations of long-term thermal performance.