Geomechanical characterization of sedimentary basins using tectonic stress and strain

Abstract

We examine whether the combination of tectonic stress and strain is useful in characterizing tectonic condition and geomechanics of sedimentary basins. We compile measured stress, pore pressure, and mechanical rock property data from six major sedimentary basins worldwide. We find that the measured horizontal principal stresses are always higher than the theoretically calculated stresses based on a simple uniaxial compaction poroelastic equation, known as Eaton’s model. From this we conclude that there are always external tectonic stresses in seemingly stable basins. We extract these external tectonic stresses by subtracting the theoretically calculated horizontal stresses from the measured horizontal stresses, and relate them to the tectonic strains estimated by the linear elastic constitutive model. Given the external tectonic stresses and associated strains, we interpret the tectonic conditions of individual basins from the tectonic differential stress and strain conditions. The six basins exhibit distinct tectonic stress and strain regimes, which can be related generally to geological processes such as brittle and ductile deformation. The results show that combining tectonic stress and strain is useful in characterizing sedimentary basins.