3D FINITE ELEMENT MODEL FOR MECHANICAL AND CHEMO-MECHANICAL DEFORMATION IN SEDIMENTARY BASINS

André Brüch¹; Samir Maghous¹

¹ Federal University of Rio Grande do Sul

doi:10.20906/CPS/CILAMCE2015-0078

Resumo

Sedimentary basins result from deposition of an appreciable amount of sediments which are transformed into rock through natural phenomena involving mechanical and chemo-mechanical deformation. Purely mechanical deformation prevails in the upper layers of basins, whereas chemo-mechanical deformation dominates at depth, where effective stresses and temperature are higher. The aim of the present contribution is to provide a comprehensive 3D framework for modeling both mechanical and chemo-mechanical compaction in sedimentary basins. Extending concepts previously proposed for the modeling of purely mechanical compaction in finite poroplasticity, chemo-mechanical deformation induced by Intergranular Pressure-Solution (IPS) is addressed by means of additional viscoplastic terms in the state equations of the porous material. Special attention is given on the analysis of the effects of large irreversible porosity changes on the poromechanical properties of the sediment material. The sedimentary basin is modeled as a fully saturated poro-elasto-visco-plastic material undergoing large strains. The numerical simulation is performed through the finite element method. An oceanic sedimentary basin is modelled as a horizontal infinite layer where sediments deposition occurs over tens of millions of years. The evolution on time of the porous material constitutive model is presented and analyzed in conjunction with the overall behavior of the sedimentary basin.

Palavras-chave: Sedimentary Basin; Poroviscoplasticity; Chemo-Mechanical Compaction; Intergranular Pressure-Solution