3D IMAGE ANALYSIS OF DEFORMATION BANDS IN POROUS CARBONATE GRAINSTONES

Miller Zambrano1, Emanuele Tondi1, Lucia Mancini2, Gaetano Dinolfo3, Nijiati Aibibula4, Fabio Arzilli5 and Giuseppe Napoli3, (1)University of Camerino, School of Science and Technology, Geology Division, Camerino, Italy, (2)Elettra - Sincrotrone Trieste, Basovizza (Trieste), Italy, (3)University of Palermo, Department of Earth and Marine Science, Palermo, Italy, (4)University of Camerino, School of Science and Technology - Geology Division, Camerino (Macerata), Italy, (5)Istituto Nazionale di Geofisica e Vulcanologia, Pisa, Italy

Contact First Author: Miller Zambrano; miller.zambrano@unicam.it

Abstract ID#: 34805

 

English Abstract:
Recent studies based on field and laboratory data have documented the effects of Deformation Bands (DBs) in fluid flow in porous rocks. The hydraulic properties of porous carbonates rocks could change abruptly due to the presence of DBs. The inner structure of DBs could show high variability in terms of textural and petrophysical properties, which have been traditionally assessed with 2D microscopy techniques.

The aim of this work is to perform a quantitative 3D image analysis of the microstructure of DBs hosted in porous carbonate grainstones by using a non-destructive 3D-imaging technique. The experiments consisted of the synchrotron X-ray computed microtomography (micro-CT) characterization of rock samples prepared in small parallelepipeds (4x4x40 mm size) and corresponding to grainstones highly affected by DBs exposed in San Vito Lo Capo peninsula (Sicily, Italy), Favignana Island (Sicily, Italy) and Majella Mountain (Abruzzo, Italy). For the analysis, the data is segmented in two main components porous and solid phases. The properties of interest are porosity, connectivity, a grain and/or porous textural properties, in order to differentiate host rock, DBs and their inner structure.

The preliminary results of the quantitative X-ray micro-CT image analysis indicate trends of porosity and connectivity for host rock, DB and zones therein. San Vito Lo Capo’s sample presents the most complex structure of DB, which is composed by three inner zones. Wherein, the porosity and connectivity are reduced from the outer to the inner zone of the DB due to grain compaction, cementation and grain size reduction. For the samples of Favignana Island and Majella Mountain, no differentiated zones within the DBs were found. However, for the Majella Mountain’s sample we observed a low porosity zone surrounding the DB that could be the result of water interaction. In general, we noted that the porous space within DB is poorly connected and it is about five times less than in the surrounding host rock. The preliminary results presented in this study and future analysis may be helpful for better understanding the inner structure of deformation bands and their implications to fluid flow in porous carbonates.

Keywords: Deformation bands, Grainstones, X-ray computed tomography.

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