Velocity data generally come from five sources: vertical seismic profiles (VSPs), checkshot surveys, [[synthetic seismograms]], stacking velocities, and well depth to time correlations. The latter is an easy and reliable method of determining velocities. Simply match the time of a horizon on a seismic line with the depth of that horizon in an adjacent well and you can calculate a velocity. This method may not work in highly deformed rocks, in which one is unsure exactly what the two-dimensional seismic line is imaging. However, depth to time correlations generally work well. | Velocity data generally come from five sources: vertical seismic profiles (VSPs), checkshot surveys, [[synthetic seismograms]], stacking velocities, and well depth to time correlations. The latter is an easy and reliable method of determining velocities. Simply match the time of a horizon on a seismic line with the depth of that horizon in an adjacent well and you can calculate a velocity. This method may not work in highly deformed rocks, in which one is unsure exactly what the two-dimensional seismic line is imaging. However, depth to time correlations generally work well. |