Velocity analysis using nonhyperbolic moveout in transversely isotropic media

Journal Article · Fri Oct 31 23:00:00 EST 1997 · Geophysics

DOI:https://doi.org/10.1190/1.1444285· OSTI ID:597034

Alkhalifah, T ^[1]

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1. Colorado School of Mines, Golden, CO (United States). Center for Wave Phenomena

P-wave reflections from horizontal interfaces in transversely isotropic (TI) media have nonhyperbolic moveout. It has been shown that such moveout as well as all time-related processing in TI media with a vertical symmetry axis (VTI media) depends on only two parameters, V{sub nmo} and {eta}. These two parameters can be estimated from the dip-moveout behavior of P-wave surface seismic data. Alternatively, one could use the nonhyperbolic moveout for parameter estimation. The quality of resulting estimates depends largely on the departure of the moveout from hyperbolic and its sensitivity to the estimated parameters. The size of the nonhyperbolic moveout in TI media is dependent primarily on the anisotropy parameter {eta}. An effective version of this parameter provides a useful measure of the nonhyperbolic moveout even in v(z) isotropic media. Moreover, effective {eta}, {eta}{sub eff}, is used to show that the nonhyperbolic moveout associated with typical TI media (e.g., shales, with {eta} {approx_equal} 0.1) is larger than that associated with typical v(z) isotropic media. The departure of the moveout from hyperbolic is increased when typical anisotropy is combined with vertical heterogeneity. Although estimation of {eta} using nonhyperbolic moveouts is not as stable as using the dip-moveout method of Alkhalifah and Tsvankin, particularly in the absence of large offsets, it does offer some flexibility. It can be applied in the absence of dipping reflectors and also may be used to estimate lateral {eta} variations. Application of the nonhyperbolic inversion to data from offshore Africa demonstrates its usefulness, especially in estimating lateral and vertical variations in {eta}.

• OSTI ID: 597034
• Journal Information: Geophysics, Journal Name: Geophysics Journal Issue: 6 Vol. 62; ISSN GPYSA7; ISSN 0016-8033
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CALCULATION METHODS
DATA ANALYSIS
RESERVOIR ROCK
SEISMIC P WAVES
SEISMIC SURVEYS