Electronic Resource
Oxford, UK
:
Blackwell Publishing Ltd
Geophysical prospecting
27 (1979), S. 0
ISSN:
1365-2478
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Geosciences
,
Physics
Notes:
The reliable determination of the root-mean-square seismic velocity from multiple coverage seismic reflection data requires coherent horizontal reflections equally spaced in time. Observational error in the rms-velocity data produces significantly greater error in the instantaneous or interval velocity.A cubic spline approximation technique developed by Powell (1967) is designed to minimize the rapid velocity variation due to observational error and retain the significant variation in the rms-velocity data. The approximation algorithm requires the difference between the observed and approximated rms-velocity to be statistically random, and seeks to follow the “real” trends in the rms-velocity measurements and reject observational error. Provided the trends of the rms-velocity are reproduced, the instantaneous velocity derived from the spline approximation to rms-velocity data with significant scatter is more reliable than the interval velocity determined from the inaccurate rms-velocity values using the Dix (1955) approximation. This interval velocity is also a more reliable indicator of variations of lithology.The utility of the spline approximation of rms-velocity is illustrated for a special common depth point (CDP) expanding reflection spread test recorded in Hardeman County, Texas by the Consortium for Continental Reflection Profiling (COCORP). In this wave test reflections are observed from several CDPs which are closely spaced. It is desired to combine the inaccurate observations from a collection of nearby CDPs. The approximation algorithm for the rms-velocity determination is applied to both the rms-velocity data for the individual CDPs and the collection of rms-velocity data for eight nearby CDPs.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-2478.1979.tb00978.x
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