Integrated seismic analysis of carbonate reservoirs: From the framework to the volume attributes

Sarg, J. F.; Schuelke, James S.

doi:10.1190/1.1599689

Cited by 14 publications

(3 citation statements)

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“…For completeness, here we discuss the parameter-estimation results for mild tilts . While such models are not plausible if the anisotropy is caused by dipping fractures, they may be adequate for effective TTI models formed by progradational sequences ͑e.g., Sarg and Schuelke, 2003͒. The scatter in the inversion results for a tilt of 20°is slightly higher than that for large tilts, but the standard deviations are less than 0.03 for ⑀ and ␦, 3% for V P0 , V S0 , and z, and 2°for ͑Figure 14͒.…”

Section: Models With Mild Tiltmentioning

confidence: 86%

“…Other examples of subsurface TTI formations ͑Figure 1͒ include progradational clastic or carbonate sequences ͑e.g., Sarg and Schuelke, 2003͒ and dipping shale layers near salt domes and in fold-and-thrust belts such as the Canadian Foothills ͑e.g., Isaac and Lawton, 1999;Vestrum et al, 1999;Grechka et al, 2001͒. The TTI medium is parameterized here by the velocities of P-and S-waves in the symmetry direction ͑V P0 and V S0 , respectively͒, the tilt of the symmetry axis from the vertical , and Thomsen's ͑1986͒ anisotropic coefficients ⑀, ␦, and ␥ defined in the coordinate system associated with the symmetry axis ͑Tsvankin, 2001͒.…”

Section: Introductionmentioning

confidence: 99%

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Modeling and inversion of PS-wave moveout asymmetry for tilted TI media: Part I — Horizontal TTI layer

Dewangan

Tsvankin

2006

GEOPHYSICS

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One of the distinctive features of mode-converted waves is their asymmetric moveout ͑i.e., the PS-wave traveltime in general is different if the source and receiver are interchanged͒ caused by lateral heterogeneity or elastic anisotropy. If the medium is anisotropic, the PS-wave moveout asymmetry contains valuable information for parameter estimation that cannot be obtained from pure reflection modes. Here, we generalize the so-called PP + PS = SS method, which is designed to replace reflected PS modes in velocity analysis with pure ͑unconverted͒ SS-waves, by supplementing the output SS traces with the moveout-asymmetry attributes of PSwaves. The time-asymmetry attribute ⌬t PS is computed in the slowness domain as the difference between the paired traveltimes of the PS arrivals corresponding to ray parameters ͑horizontal slownesses͒ of equal magnitude but opposite sign. Another useful asymmetry attribute is the offset x min of the PS-wave traveltime minimum on a common-midpoint ͑CMP͒ gather. We demonstrate the effectiveness of the developed algorithm and the importance of including the asymmetry attributes of PSwaves in anisotropic velocity analysis for a horizontal transversely isotropic layer with a tilted symmetry axis ͑or TTI͒ medium. Simple analytic expressions for the moveout asymmetry of PSV-waves, derived in the weak-anisotropy approximation, are verified by anisotropic ray tracing. The attribute ⌬t PS is proportional to the anellipticity parameter and reaches its maximum when the symmetry axis deviates by 20°-30°from the vertical or horizontal direction. All relevant parameters of a TTI layer can be estimated by a nonlinear inversion of the NMO velocities and zero-offset traveltimes of PP-and SS-͑SVSV͒ waves combined with the moveoutasymmetry attributes of the PSV-wave. The inversion of puremode ͑PP and SS͒ moveouts alone is nonunique, while the addition of the attributes ⌬t PS and x min yields stable parameter estimates from 2D data acquired in the vertical symmetry-axis plane. If the TTI model is formed by obliquely dipping fractures, the anisotropic parameters can be inverted further for the fracture orientation and compliances.

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Section: Models With Mild Tiltmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Modeling and inversion of PS-wave moveout asymmetry for tilted TI media: Part I — Horizontal TTI layer

Dewangan

Tsvankin

2006

GEOPHYSICS

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“…Following the methodology presented by Baaske et al (2007), these attributes were visually evaluated and compared to the known geologic model to find representative geologic trends and correlations. The geologic and mathematical significance of each selected attribute was supported by key studies (Taner et al, 1979;White, 1991;Barnes, 1993Barnes, , 2001Barnes, , 2007Brown, 1996;Chen and Sidney, 1997;Gastaldi et al, 1997;Lewis, 1997;Raeuchle et al, 1997;Skirius et al, 1999;Hart and Balch, 2000;Carr et al, 2001;Meldahl et al, 2001;Banchs and Michelena, 2002;Sarg and Schuelke, 2003;Tebo and Hart, 2005;Farzadi, 2006;Baaske et al, 2007;Chopra and Marfurt, 2007;Farzadi and Hesthammer, 2007), aiding the preselection of the seismic attributes (Table 1). Following the approach of Barnes (2007), attributes with geologic and geophysical meaning were systematically preferred to attributes with a purely mathematical meaning.…”

Section: Three-dimensional Multiattribute Seismic-facies Classificationmentioning

confidence: 99%

Characterization of a deeply buried paleokarst terrain in the Loppa High using core data and multiattribute seismic facies classification

et al. 2012

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The recognition of paleokarst in subsurface carbonate reservoirs is not straightforward because conventional seismic interpretation alone is generally not sufficient to discriminate karstified areas from their surroundings. In the Loppa High (Norwegian Barents Sea), a protracted episode of subaerial exposure occurring between the late Paleozoic and mid-TriassicLate Permian to Anisian-resulted in a significant overprinting of the previously deposited carbonate units. Here, we map the extension of the karstified areas using an integrated approach consisting of (1) a core study of critical paleokarst intervals, (2) a three-dimensional (3-D) seismic stratigraphic analysis, and (3) a 3-D multiattribute seismic facies (SF) classification. A core retrieved in the flat-topped Loppa High revealed breccia deposits at least 50 m (164 ft) thick, which probably resulted from cave collapses following the burial of the karst terrain. The SF classification was tested on a 3-D cube to (1) discriminate the respective SF related to the breccia deposits compared with other SF and (2) to estimate their spatial extent. Seismic-facies analysis suggests that breccias occupied the topmost area of the structural high, extending up to 12 km (7 mi) in width, 46 km (29 mi) in length, and tens of meters in thickness. The inference of such a large amount of breccia suggests that a significant part of this terrain was derived from

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Seismic Reflection

Sarg¹

2011

Encyclopedia of Modern Coral Reefs

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Integrated seismic analysis of carbonate reservoirs: From the framework to the volume attributes

Cited by 14 publications

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Modeling and inversion of PS-wave moveout asymmetry for tilted TI media: Part I — Horizontal TTI layer

Modeling and inversion of PS-wave moveout asymmetry for tilted TI media: Part I — Horizontal TTI layer

Characterization of a deeply buried paleokarst terrain in the Loppa High using core data and multiattribute seismic facies classification

Seismic Reflection

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