dfn_tls

Terrestrial laserscanning for fracture modelling

Example of a reflection point cloud (as Orthophoto) of a quarry located near Bad Dürkheim. (Fig. D.Laux)
Example of a reflection point cloud (as Orthophoto) of a quarry located near Bad Dürkheim. (Fig. D.Laux)

PhD thesis D. Laux

Surface outcrops of fractured rock masses can be used as reservoir analogues and provide, among others, detailed information about the fracture network characteristics.

For a quantitative analysis of fractures in quarries and road cuts terrestrial laser scanning (TLS) (Link) offers significant advantages over the traditional techniques using geological compass and tape. It provides not only a quick and comprehensive way of digital outcrop documentation, but also offers the possibility to derive various fracture properties from the x,y,z coordinates of the point cloud generated by TLS. These are the spatial orientation, the density/intensity as well as the size and termination criteria of the fractures.

Workflow of the point cloud processing. Step 1: Colorized point cloud. Step 2: Cleaning of the point cloud (e.g. Removal of Vegetation). Step 3: Interpretatin of the orientation of the planes (colorized in terms of dip angle and dip direction). Step 4: Transfer of the results to a DFN Model. (Fig. D.Laux)
Workflow of the point cloud processing. Step 1: Colorized point cloud. Step 2: Cleaning of the point cloud (e.g. Removal of Vegetation). Step 3: Interpretatin of the orientation of the planes (colorized in terms of dip angle and dip direction). Step 4: Transfer of the results to a DFN Model. (Fig. D.Laux)

These different fracture properties are required as input parameters to set-up a stochastic Discrete Fracture Network (DFN) model. Due to the large amount of fractures considered statistically significant distribution functions for the intensity parameters (e.g., P10, P32) and the orientations can be established. Furthermore, tectonic structures like faults or large joints can be implemented directly as deterministic features into the model. The resulting DFN models provides a realistic description of fractured rock masses and can be used, for example, to infer the hydraulic properties of subsurface fractured reservoirs (e.g., geothermal, conventional and unconventional hydrocarbon). Thus, the digitized reservoir analogs also help to close the scale gap between fractures and faults observed in seismic measurement and cores/logs.

Contact for further information: