Chad Hogan

Testing of Time-lapse Seismic Monitoring With Early Arrival Waveform Tomography.

Early Arrival Waveform Tomography (EWT) reveals subtle sub-wavelength perturbations in the velocity model, given a sufficiently accurate starting model. Time-lapse seismic surveys over reservoirs are typically intended to detect small changes in a relatively well-known overall velocity field due to localized effects such as carbon dioxide injection, steam injection, petroleum production, and more. EWT is ideally suited to detect and reveal the extent of these effects, both spatially and in terms of the magnitude of the effect on the velocity. Our investigations strongly suggest that this method deserves serious consideration for time-lapse seismic analysis, though many challenging questions remain. Chiefly, acquisition limitations may present the greatest hurdle to broader acceptance of the technique, and the optimal configuration of sources, receivers, and bandwidth remains an open question.

Seismic Imaging, One‐Way Wave Equations, Pseudodifferential Operators, Path Integrals, and all that Jazz

In this report we summarize an extension of Fourier analysis for the solution of the wave equation with a non‐constant coefficient corresponding to an inhomogeneous medium. The underlying physics of the problem is exploited to link pseudodifferential operators and phase space path integrals to obtain a marching algorithm that incorporates the backward scattering into the evolution of the wave. This allows us to successfully apply single‐sweep, one‐way marching methods in inherently two‐way environments, which was not achieved before through other methods for this problem.