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KAUST-IAMCS Workshop on Multiscale Modeling, Advanced Discretization Techniques, and Simulation of Wave Propagation

Kai Gao, Texas A&M University
Pressure-Dependent Seismic Velocity Model for the Fractured Rocks


The kinematic as well as the dynamic properties of seismic wave propagation in subsurface depend on the properties of the earth medium. Specially in the fractured reservoir, the wave propagation can be strongly influenced by the orientation and concentration, and other spatial properties of the fractures. Spatial properties of the fractures in the reservoir are often stress-sensitive, and therefore quantitatively describing the the stress-dependence of these properties is critical in developing accurate characterization of fractured reservoir in the modeling, imaging and inversion problem in time-lapse seismology. Seismic velocities of the rock is almost the most important and most frequently used quantity to characterize the variations of subsurface rocks. We propose a set of equations describing the pressure-dependent seismic velocities of fractured rocks based on a new unified asperity-deformation model and the effective compliance theory for fractured rock when the fractured rock contains a set of horizontally distributed (VTI) thin cracks, or vertically distributed (HTI) thin cracks, or two sets of orthogonally distributed thin cracks. With these pressure-dependent seismic velocities, one can conveniently use seven unknowns to characterize the time-lapse velocity changes of fractured reservoir.