| Title | Modeling of heat transport through fractures with emphasis to roughness and aperture variability |
|---|---|
| Authors | Nigon, B; Englert, A; Pascal, C |
| Year | 2016 |
| Conference | European Geothermal Congress |
| Keywords | Fracture, Aperture, Heat transport |
| Abstract | In homogeneous media, heat transport can be described using Fourier´s law opening for the possibility to apply the advection-dispersion equation to predict transport behavior. However, in real fractured media a “non-Fourier transport” often dominates. The latter phenomenon, characterized by asymmetric breakthrough shape, early breakthrough and long tailing cannot be described by the classical advection-dispersion equation. In the present study, we focus on heat transport within a single fracture and we explore the respective roles of fracture roughness and aperture variability. Fracture roughness has two main effects on heat transport, flow channeling and spatial variation of fluid/rock heat exchange area. Fracture aperture variability controls the variability of fracture flow and thus induces spatial variation of heat transport in a fracture. Macro-scale fracture roughness measurements have been made in the field using a terrestrial LiDAR. The measurements will be used to better describe fracture geometry taking into account discontinuity type. To further improve our understanding of heat transfer between fracture and matrix, we numerically will model heat transport as function of both fracture roughness and variable aperture using fracture roughness measurements from micro- to macro-scale natural fractures. Fracture roughness measurements will be analyzed by means of geostatistical and spectral methods in order to characterize fracture heterogeneity and to evaluate and simulate synthetic fracture geometries. Measured and calibrated synthetic fractures will be used to parameterize numerical heat transport models. We anticipate that these models will result in valid simulation of anomalous (non-Fourier) transport and will permit to better understand this behavior. |