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

Prabhakaran, R.; Urai, J. L.; Bertotti, G.; Weismüller, C.; Smeulders, D.M.J.

doi:10.1016/j.jsg.2021.104405

Large-scale natural fracture network patterns

Title

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

Author

Prabhakaran, R. (TU Delft Applied Geology; Eindhoven University of Technology)
Urai, J. L. (Rheinisch-Westfälische Technische Hochschule)
Bertotti, G. (TU Delft Applied Geology)
Weismüller, C. (Rheinisch-Westfälische Technische Hochschule)
Smeulders, D.M.J. (Eindhoven University of Technology)

Date

2021

Abstract

The Lilstock outcrop in the southern Bristol Channel provides exceptional exposures of several limestone beds displaying 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 spatially extensive, 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 over relatively short length scales of tens of metres.

Subject

Carbonates
Discrete fracture networks
Fractured pavements
Graph theory
Natural fracture networks
Spatial graphs

To reference this document use:

http://resolver.tudelft.nl/uuid:818adf34-98d9-4aa4-a36f-a10b03a4a1b2

DOI

https://doi.org/10.1016/j.jsg.2021.104405

ISSN

0191-8141

Source

Journal of Structural Geology, 150

Part of collection

Institutional Repository