A major aspect of borehole geophysics is vertical seismic profiling. There are essentially four major types of vertical seismic profiling: 1. Normal Vertical Seismic Profile (Normal VSP) 2. Offset Vertical Seismic Profile (Offset VSP) 3. Walkaway Vertical Seismic Profile (Walkaway VSP) 4. Walkabove Vertical Seismic Profile (Walkabove VSP) In Normal VSP the principle is to carry out geophone registration just below the source at a given well depth; a situation that is not usually practicable in ordinary surface seismic (where both the source and geophone are at the surface) as the explosive occupies the source position and cannot take a geophone due to noise. In Normal VSP, it is only the geophone that is displaced after each shot at the vertical top position.

For Offset VSP the source is placed at some fixed distance away, from above vertical geophone position. This enhances coverage as compared to Normal VSP. In Offset VSP, only the geophone is displaced at each shot, as in Normal VSP.

In Walkaway VSP, the source is moved away progressively from the above vertical position of the geophone (that is after each shot), resulting in yet better coverage.

Walkabove VSP is similar to Walkaway, but is used for coverage in a geosteered well. The displacement of the source is laterally above the horizontal well. In general, the type of profile chosen depends on purpose and acquisition logistics. In borehole seismic, several seismic shots are taken and a special gimballed device with different vector components takes into account the geophone orientation. The device indicates from which direction each signal. Several analyses, including arrival time and angle at reception, help in separating the different types of waves, and it is possible to track the upgoing and the downgoing waves. Since the source is at the surface and the geophone is at depth, the direct waves are descending while the reflected waves are ascending (except in cases of multiples). Better information is then obtained on the nature of the reflecting surface. The different angles of arrival of S and P waves can also be estimated. The separation of P- and S-waves also gives information on the mechanical properties of the rocks traversed. Among the various application of borehole seismic are:- identification and elimination of multiples- time-depth conversion- estimation of interval velocity- measurement of attenuation- information on nature of reflecting surface- information on formation properties by comparison with surface seismic and core data.

Although, several researches are yet going on to perfect some of the aspects.