SPWLA Glossary

VSP. A collection of seismic traces made from one-, two-, or three-dimensional geophones mounted in the same downhole tool which is anchored to the borehole wall. These traces are taken at sequential depths in a well and record the energy over a period of several seconds received from one or more sources located at the surface. The resulting profile displays the direct, reflected, refracted, and diffracted waves in both compressional and shear modes from all interfaces in the sedimentary column. It is the most accurate correlation tool for relating the well logs and lithologic logs to the field seismograms.