Poisson`s ratio in transversely isotropic media and its effects on amplitude response: An investigation through physical modeling experiments
Amplitude interpretation is a seismic technique that has proven to be an effective tool in oil reservoir delineation, particularly in development areas. Amplitude variation with offset is a commonly used method in amplitude interpretation. It can distinguish a hydrocarbon bearing sand reservoir from a water bearing reservoir. The well-known simplifications by Shuey of Zoeppritz`s equation is widely used in interpretation. It assumes that the media involved are isotropic. Blangy provided an expression for reflection coefficients in the presence of anisotropy. This is expressed in terms of the phase angle which does not correspond to the conventional angle of incidence obtained directly from ray path geometry. Poison`s ratio also becomes directionally dependent in anisotropic media. This paper presents the results of physical modelling of seismic reflection, where the upper medium is transversely isotropic with a vertical axis of symmetry. The second layer consisted of various water saturated sand bodies, and a high speed dry solid. Reflection amplitudes were compared with the theoretically predicted values from Blangy`s formula. For this to be done, it is necessary to use the angle of incidence defined in terms of the anisotropic phase velocity direction, rather than the geometrically determined ray angle. This was accurately achieved once the elastic constants of the anisoropic layer were determined by the method of Okoye et al. The results of these experiments show the relationship between the difference of the Poisson`s ratio and the reflection coefficients on the interface. These relationships then can be used to provide amplitude interpretation more accurately.
- OSTI ID:
- 542889
- Report Number(s):
- CONF-951013-; TRN: 97:004463-0077
- Resource Relation:
- Conference: SEG `95: 65. annual meeting and international exposition of the Society of Exploration Geophysicists (SEG), Houston, TX (United States), 8-13 Oct 1995; Other Information: PBD: 1995; Related Information: Is Part Of SEG/Houston `95 - technical program; PB: 1623 p.
- Country of Publication:
- United States
- Language:
- English
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