Soon : Petrophysics, a database for petrophysical properties of rocks.
Soon : magnetism for Archeology.
RECO3D : Development of a tool for fractures characterization on 3D outcrop.
The scientific context
Fractures are discontinuities in the rocks that can be formed by multiple geological processes and play an important role in numerous geological contexts. They have the main impact on rock stability in slope or boreholes, are the host of mineralization explored for some mining ores, or are important flow conduits in many applications from geothermal to oil&gas industries. It is especially the case for the so-called « unconventional » reservoirs for which the hydraulic and mechanical modelling have to take into account these elements to be predictive.
To characterize and include the fractures in the geological models, the classical analysis methods are with fracture maps or scan lines at the outcrop or with borehole imagery. These analyses help to determine fracture organization in space, their orientation and length distribution, fracture network connectivity… More the collected data are statically robust, more the models integrate different properties, more the representation of the geological object will be accurate and the modelling results will be predictive. However, two main difficulties are encountred when the measured properties have to be transfered to numerical modelling:
- The fracture network is a complex 3D object and the link between measures on maps (2D) or on scan lines (1D) is not obvious and needs hypothesis or simplification that bring uncertainities in the model.
- Fractures are present from the scale of the grain of the rock to kilometric surfaces that it is never possible to study as a whole. The fractures with length from decameter to hectometer are particularly undersampled while they play a first order role at the scale of buried reservoir.
The RECO3D project
The objectives of the RECO3D project is to take advantage of the development of UAVs and Aerial LIDAR to characterize the fracture network on outcrops with two main purposes:
- The characterization of fractures with decametric to hectometric length on cliffs and quarries.
- Lay the foundation of a characterization tool for fractures in 3D, in order to reduce the uncertainities in fracture network modelling.
In the project, typical outcrops are thus reconstructed in 3D using the technique of photogrammetry. On these digital data, a plug-in for automatic detection of fracture planes is developed with our partner Tessael, in order to generate a 3D fracture network. The robustness of the detection of plans is the heart of the innovation and will be tested by comparing results with classical analysis methodologies on maps or by scan lines directly in the field.
This plug-in should thus make it possible to offer an advanced characterization service of fracture networks for the needs of digital models. It is also a first R&D milestone that will allow working on reducing uncertainties in the characterization of fracture networks and their integration into existing modeling software.
This project is supported by BPI France from spring 2021 to 2022.