With a Zero Offset VSP, the source is placed at a static surface position a relatively short distance away from the wellhead. As well as recording the travel time of the seismic signal, the complete downgoing and upgoing reflected energy of the signal is recorded and processed to produce an image of the seismic reflectors in the subsurface. Key factors in producing an image are to record at regular receiver depth intervals and to record for long enough to receive later-arriving reflections. The receiver depth interval is typically in the range of every 25-50 ft (7.5-15 m). This regular spacing allows separation of the up- and down-going waves, which is a key step in vertical seismic profile (VSP) processing.
Applications:
- Time-depth correlation
- Structural and stratigraphic imaging
- Reservoir characterization by delineation of faults and pinchouts P and S wave analysis
- Polarization studies
- Improved vertical and lateral resolutions
- Phase determination and matching of surface seismic
- Extraction of parameters for enhanced surface seismic processing
- Generation of a high-resolution velocity model at the wellbore
- Salt proximity and sub-salt imaging
