About the project
The PhD project focuses on advancing microseismic waveform inversion in fractured anisotropic media, with particular emphasis on resolving microseismic source parameters. Microseismic events are typically induced during fluid injection or extraction activities—such as hydraulic fracturing, CO₂ sequestration and geothermal energy production—when slip occurs along critically stressed faults. These events act as localized seismic sources whose radiation patterns encode valuable information about fracture geometry, stress orientation, and reservoir dynamics. They can be described by source parameters that include the seismic moment tensor components (double-couple and non-double-couple contributions), event location, origin time, and source-time function. Accounting for anisotropic effects is essential to reliably determine the event location and focal mechanism and enhance the mapping of subsurface heterogeneity from recorded seismic data.
To achieve the research objective, the study address the development of rock physics-based full waveform inversion (FWI) methods. The inversion framework, based on a local optimization strategy, minimizes waveform misfits by iteratively updating the microseismic source parameters. This process refines estimates of moment tensors, focal depths, rupture orientations, and source-time functions in the presence of anisotropy-induced waveform distortions. In parallel, the anisotropic velocity model is obtained using FWI of controlled-source seismic data through an inverse scattering approach, which is naturally target-oriented and well-suited for time-lapse studies of velocity changes. By providing the sensitivity kernel in a matrix-free manner, the developed inverse scattering algorithm seeks to efficiently recover both elastic properties of the medium and fracture characteristics.
The results enable more robust interpretation of induced seismicity, reservoir fracture networks, and stress redistribution. Furthermore, accurately characterized microseismic sources provide an additional illumination of regions that are poorly imaged by conventional controlled-source seismic surveys.
People
Project members
Ujjwal Shekhar - PhD Candidate