Shear‐wave polarizations and subsurface stress directions at Lost Hills field

Winterstein, D. F.; Meadows, Mark A.

doi:10.1190/1.1890017

Cited by 37 publications

(52 citation statements)

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“…This has been observed in both multicomponent seismic reflection data (Squires et al, 1989;Lewis et al, 1991), and vertical seismic profiles (VSPs) (Winterstein and Meadows, 1991). Although most processing techniques designed for multicomponent VSPs have taken into account polarization changes (e.g., Winterstein and Meadows, 1991;Lefeuvre et al, 1992;Zeng and MacBeth, 1993a), those designed for multicomponent seismic reflection data often assume constant polarization direction (e.g., Alford, 1986;Thomsen, 1988;Li and Crampin, 1993a).…”

Section: Introductionmentioning

confidence: 93%

“…The polarization direction of the leading split shear wave may give information about the orientation of in-situ stresses, and these stresses strongly affect several reservoir characteristics related to drilling, simulation and production (Bruno and Winterstein, 1994). In recent years, many processing techniques have been developed to estimate and interpret this polarization azimuth from recorded multicomponent seismic data (e.g., Alford, 1986;Thomsen, 1988;Winterstein and Meadows, 1991;Li and Crampin, 1993a;Lefeuvre et al, 1992;Zeng and MacBeth, 1993a, b;MacBeth et al, 1994). The polarization azimuth of the leading split shear wave, as related to the direction of the maximum in-situ stress, may vary both laterally with structural location and vertically with depth due to material properties, stratigraphy, bedding, and faults (Warpinski and Teufel, 1991).…”

Section: Introductionmentioning

confidence: 99%

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Data‐matrix asymmetry and polarization changes from multicomponent surface seismics

MacBeth

1997

GEOPHYSICS

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We present methods for interpreting data-matrix asymmetry and polarization changes with depth from multicomponent surface seismics. There are two main sources of data matrix asymmetry in four component shear-wave seismics: that arising from the acquisition geometry caused by source and receiver misorientation, misalignment, imbalance, and cross-coupling, and that arising from the medium caused by variations in the geological structure, lithology, or stress. The asymmetry caused by acquisition geometry is more significant than that from the medium. Two asymmetry indices are used to quantify these medium and acquisition asymmetries separately. Their behavior may be used to identify the origin of the asymmetry.The asymmetry caused by the medium is studied by deriving approximate normal-incidence, plane-wave reflection coefficients for an interface separating two anisotropic media with differently oriented symmetry axes. The degree of asymmetry in the reflectivity is proportional to the product of the degree of anisotropy in the layers above and below the reflector, and is thus small for most realistic cases. Consequently, the reflection coefficients can be approximated by a similarity transform of the principal reflection coefficients using the expected polarization difference. These equations can then be used to formulate a singular-value decomposition (SVD) in the time-domain to recover both the principal reflectivity and the changes of polarizations with depth. Applications to field data in south Texas reveal the potential of the technique, and zones of polarization changes in the Austin Chalk are identified that may be correlated with fracture swarms.

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Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Data‐matrix asymmetry and polarization changes from multicomponent surface seismics

MacBeth

1997

GEOPHYSICS

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“…In the case where the principle directions of azimuthal anisotropy vary with depth, this algorithm needs to be augmented with a layer-stripping procedure; see Winterstein and Meadows (1991) for VSPs, and Thomsen et al (1999) for surface surveys (also giving a vector algebra for analyzing such data sets).…”

Section: Small Anisotropy Can Cause Completely New Effectsmentioning

confidence: 99%

75-plus years of anisotropy in exploration and reservoir seismics: A historical review of concepts and methods

2005

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The idea that the propagation of elastic waves can be anisotropic, i.e., that the velocity may depend on the direction, is about 175 years old. The first steps are connected with the top scientists of that time, people such as Cauchy, Fresnel, Green, and Kelvin. For most of the 19th century, anisotropic wave propagation was studied mainly by mathematical physicists, and the only applications were in crystal optics and crystal elasticity. During these years, important steps in the formal description of the subject were made.At the turn of the 20th century, Rudzki stressed the significance of seismic anisotropy. He studied many of its aspects, but his ideas were not applied. Research in seismic anisotropy became stagnant after his death in 1916. Beginning about 1950, the significance of seismic anisotropy for exploration seismics was studied, mainly in connection with thinly layered media and the resulting transverse isotropy. Very soon it became clear that the effect of layerinduced anisotropy on data acquired with the techniques of thattime was negligible, so for the next few decades the subject was studied only by a handful of researchers.In the last two decades of the 20th century, anisotropy changed from a nuisance to a valuable asset. Gupta and especially Crampin pointed out that cracks in a rock mass lead to observable effects from which, in principle, the orientation and density of the cracks could be deduced. Since this information has direct significance for the reservoir properties of the rock, the interest in seismic anisotropy increased considerably. Improvements in acquisition technology, with well-designed approximations that made the complicated theory manageable and with efficient algorithms running on more powerful computers, have turned the theoretical ideas of the early times into an important exploration and production tool. Although seismic anisotropy is usually weak, it nevertheless has important consequences in our modern data. Thus, today anisotropy is an important issue in exploration and reservoir geophysics, and it belongs in every exploration geophysicist's toolkit. EARLY ELASTIC ANISOTROPYThe theory of elastic-wave propagation was formulated early in the 19th century, and very soon elastic anisotropy was Manuscript

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“…In this respect, estimation of the shear-wave attributes is model-based or parametric, as it is carried out using known matrix equations for anisotropic wave propagation through a horizontal plane-layered structure. Many popular analysis techniques have been introduced to obtain the seismic anisotropy parameters, including the numerical rotation of Alford (1986), dual source cumulative rotation technique (Zeng and MacBeth, 1993), the layer stripping approach (Winterstein and Meadows, 1991), and etc. However, these algebraic processing techniques are applied in the time-domain.…”

Section: Introductionmentioning

confidence: 99%

Algebraic processing technique for extracting frequency-dependent shear-wave splitting parameters in an anisotropic medium

Han

Zeng

2011

Appl. Geophys.

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Based on the dual source cumulative rotation technique in the time-domain proposed by Zeng and MacBeth (1993), a new algebraic processing technique for extracting shear-wave splitting parameters from multi-component VSP data in frequency-dependent medium has been developed. By using this dual source cumulative rotation technique in the frequency-domain (DCTF), anisotropic parameters, including polarization direction of the shear-waves and timedelay between the fast and slow shear-waves, can be estimated for each frequency component in the frequency domain. It avoids the possible error which comes from using a narrow-band fi lter in the current commonly used method. By using synthetic seismograms, the feasibility and validity of the technique was tested and a comparison with the currently used method was also given. The results demonstrate that the shear-wave splitting parameters frequency dependence can be extracted directly from four-component seismic data using the DCTF. In the presence of larger scale fractures, substantial frequency dependence would be found in the seismic frequency range, which implies that dispersion would occur at seismic frequencies.Our study shows that shear-wave anisotropy decreases as frequency increases.

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Shear‐wave polarizations and subsurface stress directions at Lost Hills field

Cited by 37 publications

References 1 publication

Data‐matrix asymmetry and polarization changes from multicomponent surface seismics

Data‐matrix asymmetry and polarization changes from multicomponent surface seismics

75-plus years of anisotropy in exploration and reservoir seismics: A historical review of concepts and methods

Algebraic processing technique for extracting frequency-dependent shear-wave splitting parameters in an anisotropic medium

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