Abstract
One of the major goals of seismic data processing is to produce an accurate image of the subsurface of the earth. Unfortunately, when dipping events or diffractions are present, or when velocities vary laterally, the normal-moveout (NMO) correction applied in common midpoint (CMP) stacking fails to convert even primary events on non-zero offset traces to true zero offset. Dip moveout (DMO) is a process that converts non-zerooffset data to true zero offset after NMO has been applied. Direct comparison of compressional (P) and shear (S) wave data in a fractured reservoir can show whether amplitude anomalies on the P-wave section are associated with the presence of gas or change of lithology. The P-wave and S-wave data selected for this study were shot in Burleson County, Texas. After processing, the P-wave and S-wave sections were interpreted. No gas-related DHf (direct hydrocarbon indicator) was seen in both sections. Comparison of both sections before and after DMO shows that DMO has helped imaging the fractures in the Austin Chalk and provided a clear image of the subsurface after migrating the DMO data. Major reflectors such as the Pecan Gap, "Top-of-the-Austin-Chalk", "Bottom-of-theAustin-Chalk", and Buda correlate well with seismic events on the synthetic seismogram which was generated from the sonic log of the Lancier Brinckman #1 well. The difference in depth between the sonic log and the P-wave seismic section is small. The sonic log depths are deeper than the P-wave seismic section depths. The top and bottom of the Austin Chalk reflectors on both sections display laterally varying amplitudes (surface locations 55 to 68). This region coincides with the high-oil production zone (fractured zone).
Al-Misnid, Abdulaziz Mugbel (1994). Comparison of P-wave and S-wave data processed by DIP moveout. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1994 -THESIS -A449.