Fold-related deformation bands in a weakly buried sandstone reservoir analogue: A multi-disciplinary case study from the Numidian (Miocene) of Sicily (Italy). (January 2019)

• Record Type: Journal Article
• Authors: Gambino, S.; Fazio, E.; Maniscalco, R.; Punturo, R.; Lanzafame, G.; Barreca, G.; Butler, R.W.H.
• Is Part Of: Journal of structural geology. Volume 118(2019)
• Page Start: 150
• Page End: 164
• Publication Date: 2019-01
• Subjects: Deformation bands -- Numidian sandstones -- Porosity -- X-ray microtomography -- Reservoir analogue; Geology, Structural -- Periodicals; Géomorphologie structurale -- Périodiques; Geology, Structural; Periodicals; 551.805
• DOI: 10.1016/j.jsg.2018.10.005
• Languages: English
• ISSNs: 0191-8141

Abstract

Abstract: Deformation bands, usually recognized in association with faults, are here analyzed in relation to a tight synclinal fold developed in the Miocene Numidian turbidites of Sicily. Deposited above a growing thrust-wedge and then buckled during continued deformation, the porous Numidian sandstones form subsurface gas reservoirs elsewhere in the region and are analogues for deepwater systems in general. Structural data have been collected and statistically analyzed to characterize preferred orientations and size parameters (thickness, spacing, length) of deformation bands. Two distinct populations relate to folding: the most recent one is NE-SW oriented, which produced the most prominent structures, whereas an older one is partially obliterated. Microscopic investigation reveals porosity decreases within deformation bands with respect to host rock. The principal deformation mechanisms are grain rotation/sliding and pore-collapse, consistent with folding having occurred under low burial conditions. Within the thrust wedge, near-surface folding is widespread, as indicated by growth strata. Thus we expect early-burial deformation bands of the types (compaction and shear bands) illustrated here to be a component of reservoir damage in subsurface examples. Highlights: Deformation bands (DBs), developed at shallow burial depth during folding into a thrust system, have been investigated. Spatial orientation of multiple arrays of DBs are useful to reconstruct 3D flow model channelling within a porous medium. DBs can act both as channels or rather as barriers influencing fluids migration (gas, oil). Full characterization of DBs is of great importance in the management of field gas production. Compaction bands are characterized by lower porosity with respect to host rock.Shear-type bands, often evolving to fractures, are preferential way for fluid migration.