scholarly journals Modeling the effects of fracture infill on frequency-dependent anisotropy and AVO response of a fractured porous layer

2021 ◽  
Author(s):  
Yan-Xiao He ◽  
Xin-Long Li ◽  
Gen-Yang Tang ◽  
Chun-Hui Dong ◽  
Mo Chen ◽  
...  
Keyword(s):  
Incident Angle ◽  
Transverse Isotropy ◽  
Rock Physics ◽  
Dispersive Media ◽  
Frequency Dependent ◽  
Hydrocarbon Reservoir ◽  
Impedance Contrast ◽  
Fracture Fluid ◽  
Rock Physics Modeling ◽  
Physics Modeling

AbstractIn a fractured porous hydrocarbon reservoir, wave velocities and reflections depend on frequency and incident angle. A proper description of the frequency dependence of amplitude variations with offset (AVO) signatures should allow effects of fracture infills and attenuation and dispersion of fractured media. The novelty of this study lies in the introduction of an improved approach for the investigation of incident-angle and frequency variations-associated reflection responses. The improved AVO modeling method, using a frequency-domain propagator matrix method, is feasible to accurately consider velocity dispersion predicted from frequency-dependent elasticities from a rock physics modeling. And hence, the method is suitable for use in the case of an anisotropic medium with aligned fractures. Additionally, the proposed modeling approach allows the combined contributions of layer thickness, interbedded structure, impedance contrast and interferences to frequency-dependent reflection coefficients and, hence, yielding seismograms of a layered model with a dispersive and attenuative reservoir. Our numerical results show bulk modulus of fracture fluid significantly affects anisotropic attenuation, hence causing frequency-dependent reflection abnormalities. These implications indicate the study of amplitude versus angle and frequency (AVAF) variations provides insights for better interpretation of reflection anomalies and hydrocarbon identification in a layered reservoir with vertical transverse isotropy (VTI) dispersive media.

Impacts of kerogen content and fracture properties on the anisotropic seismic reflectivity of shales with orthorhombic symmetry

2015 ◽  
Vol 3 (3) ◽  
pp. ST1-ST7 ◽  
Author(s):  
Li Yang ◽  
Xiaoyang Wu ◽  
Mark Chapman
Keyword(s):  
Transverse Isotropy ◽  
Rock Physics ◽  
Vertical Axis ◽  
Orthorhombic Symmetry ◽  
Anisotropic Rock ◽  
Weak Anisotropy ◽  
Fracture Properties ◽  
Rock Physics Modeling ◽  
Axis Of Symmetry ◽  
Physics Modeling

Shale often has strong intrinsic anisotropy, which can be described by transverse isotropy with a vertical axis of symmetry. When vertical fractures are present, shale is likely to exhibit orthorhombic symmetry. We used anisotropic rock-physics models to describe the orthorhombic properties of fractured shale, and we determined that composition and fracture properties had an impact on the azimuthal amplitude variations. Interpretation of azimuthal reflectivity variations was often performed under simplified assumptions. Although the Rüger equation was derived for weak anisotropy and for transverse isotropy with a horizontal axis of symmetry, our results indicated that the orthorhombic response can be well described by the Rüger equation. However, ambiguities could be introduced into the interpretation of parameters. We suggested that careful rock-physics modeling was important for interpreting the anisotropic seismic response of fractured shale.

Integrated VTI model building with seismic data, geologic information, and rock-physics modeling — Part 1: Theory and synthetic test

Geophysics ◽  
2016 ◽  
Vol 81 (5) ◽  
pp. C177-C191 ◽  
Author(s):  
Yunyue Li ◽  
Biondo Biondi ◽  
Robert Clapp ◽  
Dave Nichols
Keyword(s):  
Seismic Data ◽  
Seismic Anisotropy ◽  
Model Building ◽  
Rock Physics ◽  
Seismic Inversion ◽  
Additional Information ◽  
Synthetic Test ◽  
Rock Physics Modeling ◽  
Physics Modeling ◽  
Geologic Information

Seismic anisotropy plays an important role in structural imaging and lithologic interpretation. However, anisotropic model building is a challenging underdetermined inverse problem. It is well-understood that single component pressure wave seismic data recorded on the upper surface are insufficient to resolve a unique solution for velocity and anisotropy parameters. To overcome the limitations of seismic data, we have developed an integrated model building scheme based on Bayesian inference to consider seismic data, geologic information, and rock-physics knowledge simultaneously. We have performed the prestack seismic inversion using wave-equation migration velocity analysis (WEMVA) for vertical transverse isotropic (VTI) models. This image-space method enabled automatic geologic interpretation. We have integrated the geologic information as spatial model correlations, applied on each parameter individually. We integrate the rock-physics information as lithologic model correlations, bringing additional information, so that the parameters weakly constrained by seismic are updated as well as the strongly constrained parameters. The constraints provided by the additional information help the inversion converge faster, mitigate the ambiguities among the parameters, and yield VTI models that were consistent with the underlying geologic and lithologic assumptions. We have developed the theoretical framework for the proposed integrated WEMVA for VTI models and determined the added information contained in the regularization terms, especially the rock-physics constraints.

Rock Physics Modeling of a Sakhalin Shelf Deposit

2010 ◽  
Author(s):  
T.V. Nekrasova ◽  
T.F. Sokolova ◽  
E.O. Malysheva ◽  
A.P. Murashka ◽  
G.G. Voykov ◽  
...  
Keyword(s):  
Rock Physics ◽  
Sakhalin Shelf ◽  
Rock Physics Modeling ◽  
Physics Modeling
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