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Model‐based shear‐wave velocity estimation versus empirical regressions [Note 1. Received July 1998, revision accepted March 1999. ...]
Author(s) -
Jørstad Arild,
Mukerji Tapan,
Mavko Gary
Publication year - 1999
Publication title -
geophysical prospecting
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.735
H-Index - 79
eISSN - 1365-2478
pISSN - 0016-8025
DOI - 10.1046/j.1365-2478.1999.00154.x
Subject(s) - geology , shear (geology) , linear regression , empirical modelling , ellipsoid , mineralogy , statistics , mathematics , geodesy , petrology , computer science , programming language
Modelling of AVO signatures for reservoir characterization requires V S estimation from other available logs when shear‐wave data are not available. We tested various models for predicting V S from P‐wave velocity, porosity and shale volume measured in well logs. Effective medium models which characterize the pore space in terms of ellipsoidal inclusions were compared with statistical V P – V S regressions. The inclusion models were calibrated by non‐linear minimization of the difference between model‐predicted velocities and actual measured velocities. The quality of the V S prediction was quantified in terms of the rms error by comparison with shear‐wave data in wells where both V P and V S were measured. The linear regressions were found to be more robust and the rms error in the prediction was comparable to effective medium model‐based predictions.