Vertical seismic profiling (VSP) with is the most common implementation of well seismic surveying. It consists of a seismic source at the surface, close to the borehole head , and a geophone situated at various depths in the well to record the seismic signal. The source remains at the same location above the geophone whatever the depth of the latter in the well. The VSP presents a vertical resolution of the order of one to ten meters. The lateral range of investigation can reach several ten to several hundred meters. Figure 2 shows an unprocessed VSP record obtained in well named B. In this type of display, the horizontal axis represents the different depths of the well geophone and the vertical axis represents the listening time. In this example, the receiver depth varies between 1045 m and 105 m, and the surface source is slightly offset (30 m) with respect to the borehole. The distance between successive positions of the geophone in the well varies from 3 m to 23 m. After processing, the VSP provides a seismic trace without multiples that is directly comparable to a surface seismic section recorded near the well. With the added constraints of log data (sonic and density), this trace represents an acoustic impedance log for the well and below the bottom of the well.

Example of VSP
(Gaz de France document)