Monday, January 26, 2015

VSP Vertical Seismic Profile

The traces of the upgoing VSP are often stacked together to yield the pattern of primary reflection for correlating to conventional seismic data.

Corridor stacks are usually better than synthetic seismograms made from well-log measurements for relating reflections to interfaces because the measurements are made at seismic frequencies and are not sensitive to logging uncertainties.

The slope of the first breaks VSP (direct-wave traveltimes) gives the velocity. Reflections have a slope opposite to the first breaks. By using this difference, it is possible to separate downgoing waves (which consist of direct waves and multiples involving an even number of reflection) from upgoing waves . The upgoing waves may be 30dB below the downgoing waves.

(Sherrif. 1995. Exploration Seismology)

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