World Geothermal Congress 2020+1
March - October, 2021

Characterization of Fracture Network Based on Photogrammetry

Madeline CHAPELET, Chrystel DEZAYES, Thomas DEWEZ

[BRGM, France]

The knowledge and the characterization of the fracture network is essential for the development of the geothermal energy in the deep fractured geological context. The better the characterization is, the better the fluid flow modelling expects the fluid pathway and therefore the geological risk is reduced. In the South-East Basin of France, several thermal anomalies exist and industrial projects are forecasted for exploiting deep fractured reservoirs (ca. 3-4 km depth). This area represents a part of the northern European continental margin of the Mesozoic Tethys (Lemoine, 1984). The basin was later affected by the Cretaceous and Tertiary deformation during the Pyrenean and Alpine orogenies, with uplift and erosion, folding and partial basin inversion (Roure et al., 1992). Our study area lies to the west of the basin, on the eastern border of the Massif Central, where Mesozoic extensional structures are preserved, due to its relatively external position relative to the Alpine deformation front, and where the Triassic and Lower Jurassic succession crops out. These sandstone and limestone formations constitutes the targets of geothermal projects. On several accessible quarries, we performed structural data measurements, like orientation, position, and observations, like type of fracture, movement, filling, from the ground. As the wall of the quarries are high and in order to complete our database at higher level, we implemented a ground-based photogrammetric method. For that, we took convergent pictures to cover the walls of the quarries from different locations to compute a 3D virtual geological outcrop based on 3D point cloud (Wenzel et al., 2013). Based on that, we develop a tool in order to calculate the distance between fractures and we measured likewise the fracture orientation by computed tool (Dewez et al., 2016) at various elevation of the walls. These measurements complete the various scales structural analysis performed in this area (Chabani et al., submitted). Dewez, T.J.B., Girardeau-montaut, D., Allanic, C., Rohmer, J., 2016. FACETS : A CLOUDCOMPARE PLUGIN TO EXTRACT GEOLOGICAL PLANES FROM UNSTRUCTURED 3D POINT CLOUDS XLI, 799–804. doi:10.5194/isprsarchives-XLI-B5-799-2016 Lemoime, M (1984) In Les marges contmentales actuelles et fossiles autour de la France (Eds G Boillot, L Montadert, M Lemome and B Blju-Duval) Masson ed, Paris, 179-217 Roure, F ,Brun, J P, Colletta, B and Van den Drlessche, J (1992) Geometry and kmematlcs of extensional structures m the Alpme Foreland Basm of southeastern France J Struct. Geol,14,503-519 Wenzel, K., Rothermel, M., Fritsch, D., Haala, N., 2013, Image acquisition and model selection for multi-view stereo, Int. Arch. Phot. Rem. Sens. & Spat. Inf. Sci., XL-5/W1, 25 – 26 Feb. 2013, Trento, Italy

        Topic: Geology Paper Number: 12021

         Session 11B: Geology 2 -- Structural Geology 1 [Tuesday 11th May 2021, 02:00 am] (UTC-8)
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