Generating a mechanically enriched DFN for a geothermal reservoir simulation
Résumé
Discrete facture network are convenient approaches to work at the reservoir scale in fractured and faulted systems. There are different ways to generate a DFN system, either by statistical or by physically based approaches, to capture more reasonable geometric features inherited from the past geological history. For an enhanced geothermal system (EGS), fluid injection is supposed to enhance the initial permeability through the (micro) fracture coalescence and/or nucleation. This work aims to generate a realistic fracture network using a mechanical approach. The main fractures will be generated using the Phase field method and according to the stress state with less uncertainties. Then the secondary fractures between the main faults and fractures will be generated randomly but according to the major stress direction. The “bridge zone” evolution between the main fractures is completely dependent on the stress state of this zone (minor and major stresses). In this way, we believe that the global uncertainties of the created fracture network will be minimized and then the injection phase could activate this bridge zone more realistically, either by shearing or by wing cracks. As a preliminary application, the new generation tool is used based on published data, extracted from the United Downs Deep geothermal project.
