Multiscale characterization of the fracture network affecting the Kuh-e-Asmari anticline (Zagros Mts., Iran), using NetworkGT and open-source aerial images

In fractured reservoirs, the characterization of the fracture network is a fundamental step for modelling the flow of the different types of geofluids at multiple scales. The classical method for the construction of fracture datasets is sampling, in the field, the fractures that are intersected by a measuring tape (i.e., the scan-line method), or intersected by and contained into a sampling area (i.e., scan-area and scan-circle method). Field-derived datasets have, however, limited sample area and resolution of the fracture network. The availability of open-source, high- resolution, easily accessible satellite and aerial images (e.g., Google Maps, Bing Maps), and the development of software and tools for the analysis of digital fracture datasets (e.g., NetworkGT) have sensibly simplified the collection and analysis of very large and continuous data sets of fractures, making possible the characterization of the fracture network at multiple scales for a single case study. In this work, we manually interpret open-source satellite and aerial images (Bing Maps) to analyze, at multiple scales, the fracture network affecting a well-known reservoir outcropping analogue: the the Kuh-e-Asmari anticline, in the Zagros fold-and-thrust belt. Three different fracture networks, obtained by manually interpreting three sets of satellite/aerial images at three fixed scales (1:50000, 1:5000 and 1:500) are analyzed using NetworkGT. We analyze the orientation, length distribution, intensity and topology of the fracture network and we compare with results obtained through scan-lines performed in the field on the same case study. The aim of this work is to highlight qualities and limits of each scale of observation and of field-derived data. We leverage on our multi- scale dataset to find potential scale relations that, if applied to other case studies, could allow to extrapolate the results obtained at a certain scale to other scales of observations.