1887

Abstract

Summary

A well log penetrating the Lower Silurain shale (S1l) in the south of the Sichuan Basin shows that this shale formation represents strong (vertically transverse isotropy) properties. Anisotropy has significant influence on the seismic amplitude variation with offset (AVO) response, so AVO analysis and inversion ignoring the influence of anisotropy can be inaccurate. In this parper, an anisotropic AVO inversion is introduced based on a modified approximation of the PP-wave reflection coefficient for media. Three attributes including the acoustic impedance (attribute A), the shear modulus weighted by an anelliptical anisotropy parameter (attribute B), and the approximated horizontal P-wave velocity (attribute C) can be simultaneously inverted by using a Bayesian-framework-based inversion scheme. A statistical rock-physics workflow is then applied to the inverted attributes for quantitative seismic interpretation. The field-data application on a lower Silurian-age shale-gas reservoir shows the feasibility of both approaches. The shale formation can be discriminated from surrounding formations by using the combination of the attributes A and C, and the gas-bearing shale can be identified through the combination of the attributes A and B.

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/content/papers/10.3997/2214-4609.201900299
2019-04-28
2024-03-28
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