Geomechanical Modeling of Stress and Deformation Associated With Salt-Sheet Advance

We use an evolutionary geomechanical model to study stress and deformation in sediments during the emplacement of a frontal-rolling salt sheet. We show that overturned-roof sediments develop high differential stresses and plastic strains. We illustrate that these high plastic strains may allow roof layers to overturn and fold below the advancing salt. Sediments fail during roof overturn but regain strength as they get buried below salt. We discuss that sediment strength and failure depend on the overall evolution of the salt system. We show that the salt-base geometry can provide a first order estimation of the level of shear as well as of the decrease in least principal stress below salt. We build our large strain models in the finite element program Elfen. We model salt as solid viscoplastic and sediments as poro-elastoplastic materials. Overall, our evolutionary models provide insights into the mechanics of salt-sheet emplacement, identify potential drilling hazards and help understand stress and deformation of basin sediments near salt.