ABSTRACT This paper introduces what's the problem with onshore time-lapse seismic and discusses how to deal with the problem, and then shows a successful land example of Western China. The study indicates that it is difficult to overcome the non-repeatability effects only by using cross-equalization and shows that it has to be using the specially designed processing techniques to deal with the non-repeatability effect. The specially designed processing techniques can enhance repeatable account of space-varying influence from the near surface and the non-repeatability factors of time-lapse seismic acquisition on land, and can obtain the image of relative preservation of amplitude, frequency, phase, waveform, and further improving resolution for the reservoir. With further integration with dynamic information, remaining oil in the reservoir can be described with the reprocessed time lapse seismic data.
ABSTRACT We have developed and implemented a new methodology using some variation of parsimonious migration to perform internal iterations inside the 3D grid tomography. First, we demigrate the common image gather's (CIG) significant reflection events (selected before by high grading the near offset stack) to get the unmigrated time gather data and related ray parameters. Second, we migrate the zero-offset event and reconstruct the computed unmigrated time gather data corresponding to the updated velocity model to derive the tomographic equation. The new approach is more accurate, rigorous and converges faster than other conventional tomography approaches. Since a migration engine is coupled with the tomography internal iterations, this approach has potential to reduce the number of prestack depth migration of seismic data while building a velocity model.