Large-scale natural fracture network patterns: Insights from automated mapping in the Lilstock (Bristol Channel) limestone outcrops

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Authors

Rahul Prabhakaran, Janos L Urai , Giovanni Bertotti , Christopher Weismüller, David M.J Smeulders

Abstract

The Lilstock outcrop in the southern Bristol Channel provides exceptional outcrop of several limestone layers with stratabound fracture networks, providing the opportunity to create a very large, complete, and ground-truthed fracture model. Here we present the result of automated fracture extraction of high-resolution photogrammetric images (0.9 cm/pixel) of the full outcrop, obtained using an unmanned aerial vehicle, to obtain a very large, full-resolution, map of the complete fracture network with nearly 350,000 ground-truthed fractures. We developed graph-based functions to resolve some common issues that arise in automatic fracture tracing such as incomplete traces, incorrect topology, artificial fragmentation, and linking of fracture segments to generate geologically significant trace interpretations. The fracture networks corresponding to different regions within the outcrop are compared using several network metrics and the results indicate both inter- and intra-network (layer to layer) structural variabilities. The dataset is a valuable benchmark in the study of large-scale natural fracture networks and its extension to stochastic network generation in geomodelling. The dataset also highlights the intrinsic spatial variation in natural fracture networks that can occur even in weakly-deformed rocks.

DOI

https://doi.org/10.31223/X5B61Z

Subjects

Earth Sciences

Keywords

carbonates, fractured pavements, natural fracture networks, spatial graphs, graph theory, discrete fracture networks

Dates

Published: 2021-03-12 14:52

Last Updated: 2021-03-17 14:51

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License

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:
None

Data Availability (Reason not available):
https://doi.org/10.4121/14039234

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