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Title: Analysis of thomsen parameters for finely layered VTI media

The range of Thomsen`s anisotropy parameters {epsilon} and {delta} for vertical transversely isotropic (VTI) media when the anisotropy is due to fine layering of isotropic elas-tic materials is considered. We show that {epsilon} lies in the range -3/8 {<=} {epsilon} {<=} {1/2}[-1], for finely lay-ered media having constant density; smaller positive and all negative values of {epsilon} occur for media with large fluctuations in the Lam{acute e} parameter {lambda} We show that sign({delta}) = sign ( - ) for constant density media, so {delta} can be either positive or negative. Among all theoretically possible random media, posi-tive and negative {delta} are equally likely in finely layered media limited to two types of constituent layers. Lay-ered media having large fluctuations in Lam{acute e} {lambda} are the ones most likely to have positive {delta}. Since Gassmann`s results for fluid-saturated porous media show that the effects of fluids influence only the {lambda} Lam{acute e} constant, not the shear modulus {mu}, these results suggest that positive {delta} occurring together with positive but small {epsilon} may be indicative of changing fluid content in layered earth.
Authors:
;
Publication Date:
OSTI Identifier:
303869
Report Number(s):
UCRL-JC--127249; CONF-971111--
ON: DE98050929; TRN: 99:002045
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: 67. annual meeting and expo of the Society of Exploration Geophysicists (SEG), Dallas, TX (United States), 2-7 Nov 1997; Other Information: PBD: 1 Apr 1997
Research Org:
Lawrence Livermore National Lab., CA (United States)
Sponsoring Org:
USDOE, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; ISOTROPY; MONTE CARLO METHOD; PARAMETRIC ANALYSIS; SEISMIC WAVES; LAYERS; REFLECTION