Seismic stratigraphic interpretation for thin layers: case studies

A quantitative analysis system was developed and successfully applied in resolving thin porous sands, which could not be revealed by traditional methods. The original seismic data was enhanced by reprocessing. The zero-phase wavelet synthetic seismograms and log information demonstrated the reliable quality of the seismic data, and provided the basis for constructing stratigraphic interpretation charts. A comput~r was used to locate the accurate coordinates of the peaks and the troughs of the seismic wavelets for the objective beds. The porosity-feet of the beds were estimated from the peak-to-trough amplitudes and time separations. Two cases of thin-bed stratigraphy in Taiwan were studied by the above-mentioned methods. Both of these cases involved porous sands imbedded in shales. The porosity-feet of the sands in Case I vary from 2 to 10 meters, at about 2,000 meters depth; those in the Case 2 vary from 2 to 5 meters. at about 1,000 meters depth. The porosity-thickness in the two cases approximates that from drilling data. Each of the cases de­ monstrates that more favorable sand zones exist than those previously drilled.