Vertical Seismic Profiles
“A vertical seismic profile (VSP) is a measurement in which a seismic signal generated at the surface of the earth is recorded by geophones secured at various depths to the wall of a drilled well” (Hardage, 1983, p. 1).
There are, in fact, many types of VSP, and the common bond is the borehole. We will look at the acquisition, processing, and interpretation of VSPs from a practical standpoint. VSPs are important because they provide a tie between seismic and borehole images, allow us to create detailed velocity profiles, assist with advanced exploration techniques such as imaging below the drill bit, and allow us to accurately estimate anisotropy parameters.
VSPs have higher resolution than surface seismic recordings, because the seismic waves mostly pass through the attenuating near-surface strata only once, which is not the case with surface-recorded data. A VSP records both downgoing energy and upgoing energy, known as wavefields. Processing of the VSP involves separating the wavefields and identifying the primary events. We interpret the VSP at each processing step to obtain a full understanding of the wavefield.
Figures & Tables
Fundamentals of Geophysical Interpretation, SEG Geophysical Monograph Series No. 13, is a practical handbook for the petroleum geophysicist. Fundamental concepts are explained using heuristic descriptions of seismic modeling, deconvolution, depth migration, and tomography. Pitfalls in processing and contouring are described briefly. Applications include petroleum exploration of carbonate reefs, salt intrusions, and overthrust faults. The book includes past, present, and possible future developments in time-lapse seismology, borehole geophysics, multicomponent seismology, and integrated reservoir characterization.