Velocity updating around salt bodies using stress modeling solutions and non‐linear elasticity

Abstract

Subsalt imaging and velocity estimation is usually a challenging task. Initial estimates of subsalt velocity often come from regional depth trends that ignore reduction in effective stress below salt, and therefore over predict subsalt velocities. We present a geomechanically constrained approach to improve velocity estimation around salt bodies using stress-strain modeling and nonlinear elasticity. Computing the full stress tensor field using 3D numerical modeling, we observe (a) significant reduction in effective stress below salt bodies, and (b) anisotropic solutions for the stress and strain tensors near the edges of the salt body. Not only are these observations expected from the basic laws of physics, but they have also been observed in reality in the form of velocity reduction below salt and velocity anisotropy near salt bodies. Our strategy is to incorporate this expected behavior into the seismic imaging workflow for improved velocity model building. Other potential applications of this method can include reservoir characterization and drilling hazard identification.