Seismic reservoir monitoring with simultaneous sources

Discussion

If the temporal spacing between seismic surveys is small, we see that a near-continuous image of reservoir property change can be obtained (Figure 6). We can reduce the acquisition cost for these conventional seismic surveys by using multiple seismic sources. Instead of separating the recorded data from such an experiment, they can be imaged directly with a phase-encoding operator. However, direct imaging causes cross-talk artifacts that degrade the quality of migrated images (Figure 7(a)). In addition, if the the acquisition geometries and relative shot-timings are not repeated, the cross-term artifacts will degrade the quality of the time-lapse images (Figure 7(b)). Regularized joint inversion attenuates these artifacts (Figure 8(a)). Furthermore, inversion also produces high-quality time-lapse images (Figure 8(b)) that are of comparable quality but better resolution than perfectly repeated single-source data sets (Figure 6(b)). A careful choice of the regularization parameters ensures that the objective function is well behaved for all components of the global cost function. This leads to a gradual reduction in the cross-term and non-repeatability artifacts with iteration (Figures 9 and 10).

Seismic reservoir monitoring with simultaneous sources