1.
n. [Geophysics]
A type of
borehole seismic data designed to measure the seismic
traveltime from the surface to a known depth. P-
wave velocity of the formations encountered in a wellbore can be measured directly by lowering a
geophone to each
formation of interest, sending out a source of energy from the surface of the Earth, and recording the resultant
signal. The data can then be correlated to surface seismic data by correcting the
sonic log and generating a synthetic
seismogram to confirm or modify seismic interpretations. It differs from a
vertical seismic profile in the number and density of
receiver depths recorded; geophone positions may be widely and irregularly located in the wellbore, whereas a vertical seismic profile usually has numerous geophones positioned at closely and regularly spaced intervals in the wellbore.