The University of Texas at Austin
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We develop large strain, evolutionary geomechanical models that couple deformation with sedimentation and porous fluid flow in salt geologic systems. Salt is a viscous rock unable to sustain deviatoric stresses; instead, it flows in the subsurface forming salt bodies that extend for several km. Salt systems are associated with significant energy resources but also with large stress and pore-pressure perturbations. We find that high differential stresses develop near rising diapirs and below salt sheets. Salt emplacement induces significant excess pressures that are comparable to the weight of salt. In addition, we show that the shear-induced component of the excess pressure is significant. We also find that high pore pressures result in low strength, which enables salt growth and affects the macro-scale geological evolution. We model salt as a solid viscoplastic and sediments as poro-elastoplastic material, and calibrate the consolidation properties using experimental results on smectite-rich mudrocks from the Gulf of Mexico. Our results help advance our fundamental understanding of the interaction between pressure, stress, and deformation in basins. Furthermore, our modeling provides the foundation for a technical approach that can address many geologic systems where large strains, pore fluids, and sedimentation interact.
Maria A. Nikolinakou is a Research Scientist at the Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin. Previously, she worked for Shell E&P. She received her M.Sc. and Sc.D. on theoretical soil mechanics from Massachusetts Institute of Technology and Diploma in Civil Engineering from National Technical University of Athens, Greece. She is the Treasurer of the American Rock Mechanics Association.