GeoDFN - A Flexible, Open-Source Software for Generating Geologically Consistent Discrete Fracture Networks

GeoDFN is an open-source software that provides comprehensive control over fracture properties and allows us to explore how a broad range of geological uncertainties impact the geometry and connectivity of fracture networks. GeoDFN employs a hybrid approach, combining the advantages of mechanical and statistical methods in generating DFNs, which ensures geological consistency in fracture placement while maintaining computational efficiency. At the core of this hybrid approach is the consideration of stress shadow, as buffer zone around fractures, which impose a minimum spacing between fractures and prevent them from being placed in geologically unrealistic locations. Considering stress shadow also imposes a natural limit on the maximum fracture intensity of the network, reflecting the network saturation observed in real geological formations. Various models for calculating fracture apertures are provided in GeoDFN, including models that account for external stress conditions, such as the Barton-Bandis model. This capability enables detailed analysis of how fracture apertures influence fluid flow and network permeability under different geological conditions.
GeoDFN can be linked to any flow simulator capable of modeling fluid flow in fractured geological formations, providing a versatile tool for subsurface flow analysis. Here, we demonstrate its integration with the MATLAB Reservoir Simulation Toolbox (MRST), an open-source simulator widely used for modeling flow and transport processes. The integration with MRST enables users to easily import generated DFNs and conduct a variety of simulations, including single-phase and multiphase flow, heat transfer, and solute transport. By utilizing MRST’s Embedded Discrete Fracture Model (EDFM) approach, the complex interactions between fractures and the surrounding rock matrix are accurately represented. This connection facilitates the evaluation of how different uncertainties in fracture properties affect subsurface flow behavior, making it a powerful tool for uncertainty quantification and sensitivity analysis in diverse geological settings.