Integrating seismic fracture analysis with migration

Zheng, Ye; Gray, David

doi:10.1190/1.1816989

Cited by 4 publications

(2 citation statements)

References 7 publications

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“…At first, most migration methods are developed for imaging and regular amplitude-variation-with-offset (AVO) analysis, and we seldom need to consider azimuth information. During the transition for azimuthally anisotropic processing, commonoffset-vector migration (Cary, 1999) and azimuth-sectored migration (Zheng and Gray, 2002) were proposed to take azimuth information into consideration. Azimuth-sectored migration is still widely applied in current practice for analyzing azimuthal anisotropy and detecting fractures (Sun et al, 2011(Sun et al, , 2012b(Sun et al, , 2012cPeng et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Full-azimuth anisotropic prestack time migration in the local-angle domain and its applications on fracture detection

Sun

2015

GEOPHYSICS

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Considering that geologic structures disturb prestack amplitude relationships, anisotropic migration is thus advocated not only for extracting azimuth-preserved common image gathers (CIGs), but also for preserving fracture-induced amplitude responses. However, most conventional anisotropic migration methods are hindered by their inefficiency in either modeling azimuthal traveltime variations at large offsets or characterizing subsurface reflections. Given that prestack time migration is widely applied for most practical purposes, we began with reformulations on a quartic traveltime formula, through which a new set of anisotropic parameters was developed. Then, an anisotropic migration method was established in the localangle domain (LAD) for more reasonable uses of subsurface wavefield information. We also used a traveltime inversion scheme to estimate those anisotropic parameters required by anisotropic migration. Using this methodology on a physical model with a fracture medium, we derived better focused CIGs by thoroughly correcting the anisotropic effects of overburden. As a result, predicted properties of the fracture medium showed fewer interventions of geologic impacts. In a field example, a comprehensive study was performed on a deep carbonate reservoir to examine influences of different anisotropic migration algorithms on ultimate fracture prediction. Comparisons of the signal-to-noise ratio and agreements with formation microimage information reconfirmed the superiority of LAD anisotropic migration in recovering true properties of subsurface fractures, relative to routine methods (i.e., azimuth-sectored migration and anisotropic migration in the surface-offset domain).

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Section: Introductionmentioning

confidence: 99%

Full-azimuth anisotropic prestack time migration in the local-angle domain and its applications on fracture detection

Sun

2015

GEOPHYSICS

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“…Much work has been done in seismic fracture analysis on P wave data (e.g. Lynn et al, 1996;Teng and Mavko, 1996;Li, 1999;Gray and Head, 2000;MacBeth and Lynn, 2001;Zheng and Gray, 2002;Chapman and Liu, 2004;Chi et al, 2004;Parney, 2004;Zheng et al, 2004). Typically, a fractured zone is mathematically simplified as a Horizontally Transverse Isotropic (HTI) layer, which implies all fractures are vertical and oriented in one direction.…”

Section: Introductionmentioning

confidence: 99%

Pitfalls and tips for seismic fracture analysis

Zheng¹,

Wang²,

Perz³

2008

SEG Technical Program Expanded Abstracts 2008

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P-wave fracture analysis provides a means to extract fracture density and orientation of an underground reservoir. Good methods are important for fracture analysis, and moreover, careful handling of some practical issues is crucial. These issues include, but are not limited to, avoiding cycle skipping when applying dynamic trim statics, the confounding effects of an anisotropic overburden, and also consideration of the boundaries between two fractured zones. Any improper treatment on any of these issues can lead to incorrect outcomes of the analysis and/or misinterpretation of the analysis results.

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Azimuth-preserved local angle-domain prestack time migration in isotropic, vertical transversely isotropic and azimuthally anisotropic media

Cheng

Wang

et al. 2012

GEOPHYSICS

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Conventional prestack migration does not preserve local directional information of the seismic waves at the image points. New attempts such as sectored migration of azimuth-limited or common-offset-vector data only concern source-receiver azimuth and offset on the surface, which can be poor representation of subsurface wavepath direction. Moreover, they could result in inaccurate imaging because they do not account for the energy propagation between azimuths or offset-vectors. In the past decade, local angle-domain seismic imaging has been highly advocated to avoid migration artifacts and to improve velocity estimation in complex media. Considering prestack time migration (PSTM) is still widely used in seismic imaging and seismic data preconditioning for amplitude variations with offset or incident-angle (AVO/AVA) analysis, fracture detection, and reservoir characterization, we present an azimuth-preserved local angle-domain Kirchhoff PSTM approach for such purposes. We apply a seismic imaging condition in 3D local angle domain and use extended superposition of impulse responses retaining subsurface angular attributes, which are evaluated through the incident and scattering phase slowness vectors using classical-diffraction moveout equations in isotropic, vertical transversely isotropic (VTI) and azimuthally anisotropic media. Two-dimensional synthetic examples demonstrate what the migrated results look like in local angle domain. A wide-azimuth synthetic example with horizontal transversely isotropy (HTI) proves the necessity of azimuthal migration for reliable imaging and azimuthal analysis when azimuthal anisotropy exists in the overburden. Real data examples show the advantages of imaging in subsurface angle domain for properly focusing and revealing azimuth- and angle-dependent variations of residual moveout and migrated amplitudes.

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Integrating seismic fracture analysis with migration

Cited by 4 publications

References 7 publications

Full-azimuth anisotropic prestack time migration in the local-angle domain and its applications on fracture detection

Full-azimuth anisotropic prestack time migration in the local-angle domain and its applications on fracture detection

Pitfalls and tips for seismic fracture analysis

Azimuth-preserved local angle-domain prestack time migration in isotropic, vertical transversely isotropic and azimuthally anisotropic media

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