| Popis: |
This paper presents an original global method which computes a real time synthetic model from seismic data, during the well-tie process. Based on a relative geological time model resulting from global seismic interpretation and on synthetic seismograms, this technique intends to give a comprehensive view of the seismic-well tie and completes the standard workflow. Instead of correlating the synthetic log with the nearest seismic traces only in the vicinity of the well trajectory, a synthetic model is computed in real time by propagating the synthetic seismogram into the geological model. Minimizing the relative errors between the real seismic data and the synthetic model automatically enables the determination of the optimum time shift value to apply to the current time-depth relationship. Moreover, as stretching and squeezing the synthetic log is still controversial, the method allows to check and understand the global consequences of local change in the time-depth relationship. Such a technique can be used on a single well or on multi-well analysis. In the latter case, reference tied wells are used as hard constraints for the synthetic model. The method highlights any mismatches or polarity change and therefore is more sensitive to well-to-seismic mistie. Applied to the North Sea K05 block dataset, this approach has clearly shown successful results in improving the well calibration in complex geological areas. Using more advanced kriging techniques, the method also opens the path for future applications where rock properties or velocity models would be compared. |
