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Nonlinear Anisotropic Joint Pp-Ps Litho-Elastic Inversion: Example From Midland BasinNormal access

Authors: E. Gofer and R. Bachrach
Event name: Second EAGE/AMGP/AMGE Latin-American Seminar in Unconventional Resources
Session: Session II
Publication date: 14 November 2019
DOI: 10.3997/2214-4609.201903096
Organisations: EAGE
Language: English
Info: Extended abstract, PDF ( 589.87Kb )
Price: € 20

Summary:
In unconventional plays clay-rich shale formations are often targeted for oil and gas productions. Shale can be approximated as transversely isotropic media with vertical axis of symmetry. Amplitude versus angle (AVA) response along interfaces in such reservoirs is not only related to P- and S-impedance but also to the contrast between the anisotropic parameters. It is impossible to jointly resolve VP/VS ratio and density with the anisotropy through unconstraint AVA inversion and therefore transverse isotropy (TI) constrain must be applied. Litho-elastic (LE) inversion solves jointly for lithology and elastic parameters relaxing the dependency on the low-frequency model prior. Using lithology information LE inversion can also relax the TI constraint. Compared to P-p prestack AVA inversion, joint Pp-Psv prestack inversion can provide a more accurate estimate of VP/VS ratio and density, thus enabling a better estimate of lithological classification and petrophysical properties. Herein we demonstrate a nonlinear anisotropic joint Pp-Psv LE inversion on a 3C 3D data set from the Midland Basin.


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