Fowler DMO and time migration for transversely isotropic media with explicit operators

Conference · Thu Dec 01 04:00:00 EST 1994

OSTI ID:10128847

Anderson, J ^[1]; Alkhalifah, T; Tsvankin, I ^[2]

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1. Mobil Oil Co., Dallas, TX (United States)
2. Colorado School of Mines, Golden, CO (United States). Dept. of Geophysics

In this report, the authors devise a Fowler-type DMO algorithm for transversely isotropic media using the analytic expression for normal-moveout velocity given by Tsvankin (1995a). Alkhalifah and Tsvankin (1995) have shown that in transversely isotropic media with a vertical axis of symmetry (VTI) the P-wave normal-moveout (NMO) velocity as a function of ray parameter can be fully described by just two parameters: the zero-dip NMO velocity V{sub nmo}(O) and the anisotropic parameter {eta}. In the authors extension of Fowler DMO, resampling in the frequency-wavenumber domain makes it possible to obtain the values of V{sub nmo}(O) and {eta} by inspecting zero-offset (stacked) panels for different pairs of the two parameters. The simplest way to reduce the range of solutions in this two-dimensional search is to obtain V{sub nmo}(O) from conventional NMO velocity analysis. Since most of the computing time is spent on generating constant-velocity stacks, the added computational effort due to the presence of anisotropy is relatively minor. Synthetic and field-data examples demonstrate that the isotropic Fowler DMO technique fails to generate an accurate zero-offset section and obtain the zero-dip NMO velocity for non-elliptical VTI models. In contrast, their anisotropic algorithm allows one to find the values of the parameters V{sub nmo}(O) and {eta}, and correct for the influence of transverse isotropy in the DMO processing. Combined with poststack F-K Stolt migration, this method represents a complete inversion-processing sequence capable of recovering the effective parameters of transversely isotropic media and producing migrated images for the best-fit homogeneous anisotropic model. Although the current implementation is limited to transversely isotropic media with a vertical axis of symmetry (VTI), it can be generalized for more complicated anisotropic models.

• Research Organization: Colorado School of Mines, Golden, CO (United States). Center for Wave Phenomena
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: FG02-89ER14079
• OSTI ID: 10128847
• Report Number(s): DOE/ER/14079--38; CWP--164P; CONF-940004--2; ON: DE95007671; BR: KC0403010
• Country of Publication: United States
• Language: English

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