Double‐difference elastic waveform tomography in the time domain

Time‐lapse seismic monitoring is an indispensable diagnostic technique for assessing reservoir changes caused by heterogeneous fluid flow of bypassed oil, injected reservoir fluids such as water, steam and . However, conventional analyses of time‐lapse seismic data provide only qualitative results of reservoir changes. Full elastic waveform inversion could provide quantitative estimates of these changes. We develop a double‐difference elastic waveform tomography method in the time domain analogous to an inversion scheme proposed by Watanabe et al. (2004) for acoustic waves, which uses the differences in time‐lapse data to invert for reservoir changes. The resulting tomography images are more reliable than the differences between two independent waveform tomography results of the time‐lapse data. We demonstrate using synthetic time‐lapse elastic data that the double‐difference elastic waveform tomography is promising to quantitatively estimate reservoir changes in density, and P‐ and S‐wave velocities.