3‐D poststack phase‐shift migration in transversely isotropic media

Meadows, Mark A.; Abriel, William L.

doi:10.1190/1.1822738

Cited by 15 publications

(13 citation statements)

References 4 publications

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“…Transverse anisotropy in the GOM has been noted by many authors, including Meadows and Abriel (1994) and Gonzolez et al (1991), who have observed vertical and horizontal velocities that correspond to values of s near 0.1. Values of S have been observed in the range of 0.1 to 0.3 in GOM shales and near 0.0 in sands, with increasing values as a function of depth (Larner, personal communication, 1996).…”

Section: Comparison Of Position Errors For 2•d Mt Inversion and Seismmentioning

confidence: 88%

Marine magnetotellurics for petroleum exploration, Part II: Numerical analysis of subsalt resolution

1998

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In areas where seismic imaging of the base of salt structures is difficult, seaborne electromagnetic techniques offer complementary as well as independent structural information, Numerical models of 2-D and 3-D salt structures demonstrate the capability of the marine magnetotelluric (MT) technique to map the base of the salt structures with an average depth accuracy of better than 10%. The mapping of the base of the salt with marine MT is virtually unaffected by internal variation within the salt. Three-dimensional anticlinal structures with a horizontal aspect ratio greater than two can be interpreted adequately via two-dimensional inversions. Marine MT can distinguish between salt structures which possess deep vertical roots and those which do not.

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Section: Comparison Of Position Errors For 2•d Mt Inversion and Seismmentioning

confidence: 88%

Marine magnetotellurics for petroleum exploration, Part II: Numerical analysis of subsalt resolution

1998

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“…The anisotropy is due to variation in intrinsic properties of clay particles, total organic carbon (TOC), their thermal maturation and tendency of clay minerals to align as plates (Jones and Nur, 1984;Vernik and Nur, 1992;Mondol et al, 2010). Due to the significant importance of organic-rich shales in conventional and unconventional hydrocarbon resources, a better understanding of the velocity anisotropy is necessary to constrain seismic velocity analysis (Alkhalifah, 1996), interpretation and inversion of azimuthally varying nonhyperbolic reflection moveout in seismic signature analysis (Pech et al, 2003;Pech and Tsvankin, 2004;Grechka and Pech, 2006), amplitude variation with offset analysis (Wright, 1987), interpretation of sonic log data (Vernik and Nur, 1992), and imaging of subsurface structures (Meadows and Abriel, 1994). Moreover, knowledge of anisotropy of the hydraulic and acoustic properties of different shales may contribute to improved understanding of seal quality because the presence of fractures and microcracks in shales are important parameters to influence velocity anisotropy and pose a potential risk of cap rock failure to trap reservoir fluids.…”

Section: Introductionmentioning

confidence: 99%

Velocity anisotropy of Upper Jurassic organic-rich shales, Norwegian Continental Shelf

2017

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This study investigates the seismic velocity anisotropy of two organic-rich shales from the Norwegian Continental Shelf. The tested organic-rich shale samples were from the Upper Jurassic Draupne and Hekkingen formations collected from two wells (16/ 8-3S and 7125/1-1) drilled in the central North Sea and western Barents Sea, respectively. The two tested shales are different in organic matter richness and thermal maturation, and they have experienced different burial histories. The shale core plugs were tested in a triaxial cell under controlled pore pressure. Seismic velocities (V P and V S ) were measured along different orientations with respect to layering to identify the complete tensor of the rock elastic moduli, and to investigate the velocity anisotropy as a function of increasing effective stress. The measured velocity values exhibit strong anisotropy for the two tested organic-rich shales. The anisotropy for both shales is strongest for V S . Seismic velocities follow an increasing trend as the effective stress increases. The anisotropy decreases somewhat with increasing consolidation, probably due to the closing of preexisting fractures and microcracks. The reduction of anisotropy is more evident for the P-wave because it decreases from 0.32 to 0.25 for the Draupne sample and from 0.28 to 0.24 for the Hekkingen sample when the vertical effective stress increases from 26 to 50 MPa. In general, the Hekkingen sample indicates slightly higher velocity values than the Draupne sample due to more compaction and lower porosity. In spite of major differences between the two shale formations in terms of organic matter content, maturity and burial history, they indicate almost the same degree of velocity anisotropy. The outcomes of this study can contribute to better imaging of organic-rich Draupne and Hekkingen shales by constraining the rock-physics properties.

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“…They include Meadows, Coen and Liu (1987), who extended the imaging method of Stolt (1978) to homogeneous media with elliptical anisotropy; Uren, Gardner and McDonald (1990), who presented a 2D post-stack Stolt method for homogeneous TI; Gonzalez, Lynn and Robinson (1991), who used an approximate anelliptic dispersion relationship to implement a prestack Stolt method for P-waves in a homogeneous TI medium; Sena and Tokso È z (1993), who presented a 2D Kirchhoff algorithm (prestack) for weak TI (Thomsen 1986); Uzcategui (1995), who used explicit depth extrapolators for TI media having a vertical axis of symmetry; Meadows and Abriel (1994), who presented a 3D post-stack phase-shift time algorithm for a homogeneous TI medium to improve the image of data from the Gulf of Mexico; Kitchenside (1993), who proposed a 2D algorithm for homogeneous TI media that constructs an extrapolator in the Fourier domain (k x ±o) and applies it as a truncated and tapered filter in the space±frequency (x±o) domain; and Le Rousseau (1997) and Ferguson and Margrave (1998), who presented depth-imaging methods for heterogeneous TI media that are restricted to coincident source±receiver acquisition geometry. They include Meadows, Coen and Liu (1987), who extended the imaging method of Stolt (1978) to homogeneous media with elliptical anisotropy; Uren, Gardner and McDonald (1990), who presented a 2D post-stack Stolt method for homogeneous TI; Gonzalez, Lynn and Robinson (1991), who used an approximate anelliptic dispersion relationship to implement a prestack Stolt method for P-waves in a homogeneous TI medium; Sena and Tokso È z (1993), who presented a 2D Kirchhoff algorithm (prestack) for weak TI (Thomsen 1986); Uzcategui (1995), who used explicit depth extrapolators for TI media having a vertical axis of symmetry; Meadows and Abriel (1994), who presented a 3D post-stack phase-shift time algorithm for a homogeneous TI medium to improve the image of data from the Gulf of Mexico; Kitchenside (1993), who proposed a 2D algorithm for homogeneous TI media that constructs an extrapolator in the Fourier domain (k x ±o) and applies it as a truncated and tapered filter in the space±frequency (x±o) domain; and Le Rousseau (1997) and Ferguson and Margrave (1998), who presented depth-imaging methods for heterogeneous TI media that are restricted to coincident source±receiver ac...…”

Section: Introductionmentioning

confidence: 99%

Depth imaging in anisotropic media by symmetric non‐stationary phase shift

Ferguson¹,

Margrave²

2002

Geophysical Prospecting

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We present a new depth‐imaging method for seismic data in heterogeneous anisotropic media. This recursive explicit method uses a non‐stationary extrapolation operator to allow lateral velocity variation, and it uses the relationship between phase angle and the spectral coordinates of seismic data to allow velocity variation with phase angle. A qualitative comparison of migration impulse responses suggests that, for an equivalent cost, the symmetric non‐stationary phase‐shift (SNPS) operator is superior to the phase‐shift plus interpolation (PSPI) operator, for very large depth intervals. To demonstrate the potential of the new method, seismic data from a physical model acquired over a transversely isotropic medium are imaged using a shot‐record migration based on the SNPS operator.

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3‐D poststack phase‐shift migration in transversely isotropic media

Cited by 15 publications

References 4 publications

Marine magnetotellurics for petroleum exploration, Part II: Numerical analysis of subsalt resolution

Marine magnetotellurics for petroleum exploration, Part II: Numerical analysis of subsalt resolution

Velocity anisotropy of Upper Jurassic organic-rich shales, Norwegian Continental Shelf

Depth imaging in anisotropic media by symmetric non‐stationary phase shift

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