Synthetic Tie between Wells and Seismic

Synthetic seismograms were constructed for each of the wells with sonic logs along the Wilson Road and Rice Park seismic lines. Synthetics from DDV57 and DDV63 give a good match to the actual seismic data from the Wilson Road line. However, the synthetic seismogram for DDV67 is unable to match the series of low frequency, high amplitude reflections just below the “three-finger” interval on the extracted seismic data. It is likely that these low frequency reflections are artifacts of the overlying gas, which can not be accurately reproduced with the simple convolutional model used to create the synthetic. The synthetic seismogram for DDV5 was created using the sonic log acquired in October 2001, and is compared to the Rice Park seismic data acquired in February 2001. There is a reasonably good fit between the synthetic and the actual seismic data except within the gas zone, where the polarity of the extracted trace appears to be reversed from the synthetic. This suggests that the gas anomaly on the Rice Park seismic line may have disappeared as the gas dissipated from this location. In order to test this theory, a synthetic seismogram for DDV5 was created where the velocity within the 5-ft thick gas zone, centered on the “b” dolomite, was decreased by 2500 ft/s (from approximately 9500 ft/s to 7000 ft/s). The resulting synthetic seismogram provides a good match to the actual seismic data.

DDV57

DDV67

DDV63

DDV5

DDV5 (Velocity decreased in gas zone)