Numerical Simulation of Deformation Band Occurrence and the Associated Stress Field during the Growth of a Fault-Propagation Fold

Abstract

Knowledge of the paleo-stress distribution is crucial to understand the fracture set up and orientations during the tectonic evolution of a basin, and thus the corresponding fluid flow patterns in a reservoir. This study aims to predict the main stress orientations and evolution during the growth of a fold by using the limit analysis method. Fourteen different steps have been integrated as 2D cross sections from an early stage to an evolved stage of a schematic and balanced propagation fold. The stress evolution was followed during the time and burial of syn tectonic layers localized in front of the thrust. Numerical simulations were used to predict the occurrence and orientation of deformation bands, i.e., compaction and shear bands, by following the kinematic of a fault-propagation fold. The case study of the Sant-Corneli-Boixols anticline was selected, located in the South Central Pyrenees in the Tremp basin, to constrain the dimension of the starting models (or prototypes) used in our numerical simulations. The predictions of the numerical simulations were compared to field observations of an early occurrence of both pure compaction- and shear-enhanced compaction bands in the syn-tectonic Aren formation located in front of the fold, which are subjected to early layer parallel shortening during the burial history. Stress magnitude and stress ratio variations define the type of deformation band produced. Our results show that the band occurrence depends on the yield envelope of the host material and that a small yield envelope is required for these shallow depths, which can only be explained by the heterogeneity of the host rock facies. In our case, the heterogeneity can be explained by a significant contribution of carbonate bioclasts in the calcarenite rock, which change the mechanical behavior of the whole rock.

Disaggregation bands as an indicator for slow creep activity on blind faults

“…1). For high differential stress/effective mean stress (Q/P) ratios, the bands are oblique to the maximum stress direction 43 . Shear band orientation in unconsolidated material is grain-size dependent; in coarse sand, bands show the Roscoe orientation, θ R , and in fine sand, the Coulomb orientation, θ C 44 .…”

Quantifying occurrence of deformation bands in sandstone as a function of structural and petrophysical factors and their impact on reservoir quality: an example from outcrop analog of Productive Series (Pliocene), South Caspian Basin

“…Therefore, more efforts were put to characterize them from outcrop analogs (e.g., Sanderson 2016;Gambino et al 2019). Since deformation bands are known to influence the fluid flow in porous media, attempts were made to predict their occurrence in a rock volume (Das et al 2011;Robert et al 2019;Wu et al 2020) and quantify their impact at pore (Atilla and Ahmadov 2009;Das et al 2013) and reservoir (Botter et al 2016;Wilson et al 2021;Pourmalek et al 2021) scales.…”