Determination of Shallow Shear-Wave Attenuation in the Mississippi Embayment Using Vertical Seismic Profiling Data

2009 ◽  
Vol 99 (3) ◽  
pp. 1636-1649 ◽  
Author(s):  
J. Ge ◽  
J. Pujol ◽  
S. Pezeshk ◽  
S. Stovall
Keyword(s):  
Shear Wave ◽  
Wave Attenuation ◽  
Mississippi Embayment ◽  
Seismic Profiling ◽  
Vertical Seismic Profiling

Azimuthal investigation of compressional seismic-wave attenuation in a fractured reservoir

Geophysics ◽  
2019 ◽  
Vol 84 (6) ◽  
pp. B437-B446 ◽  
Author(s):  
Fateh Bouchaala ◽  
Mohammed Y. Ali ◽  
Jun Matsushima ◽  
Youcef Bouzidi ◽  
Eric M. Takam Takougang ◽  
...  
Keyword(s):  
United Arab Emirates ◽  
Seismic Wave ◽  
Wave Attenuation ◽  
Three Dimensional ◽  
Fractured Reservoir ◽  
Flow Mechanism ◽  
Seismic Wave Attenuation ◽  
Seismic Profiling ◽  
Vertical Seismic Profiling ◽  
The Rose

Three-dimensional vertical seismic profiling data acquired from an oilfield located in Abu Dhabi, United Arab Emirates, were used to obtain a high-resolution multioffset azimuthal estimate of compressional seismic wave attenuation. On the basis of the assumption that the fracture strike corresponds to the azimuthal direction [Formula: see text] at which the attenuation is minimized, fracture orientations were obtained in three reservoir units. Two approaches were used to determine [Formula: see text]: first from the variation of the absolute attenuation [Formula: see text] with the azimuth and second from the variation of the relative attenuation [Formula: see text] with the azimuth. The rose diagrams of [Formula: see text] estimated from the [Formula: see text] variation indicated better agreement with those showing the strikes of open and cemented fractures obtained from core interpretation than with either of those showing the two types of fractures separately. However, the rose diagrams of [Formula: see text] estimated from the variation of [Formula: see text] were more similar to those showing the strikes of open fractures obtained from core and Fullbore Formation Microimager data. This observation can be explained by the fact that in the first approach, all types of fractures contribute to the scattering and fluid-related mechanisms of [Formula: see text]. However, in the second approach, [Formula: see text] is obtained from a least-squares fitting of the variation of [Formula: see text] with the azimuth, which is based on the squirt flow mechanism that is caused by the movement of fluid between grain pores and fractures. Therefore, a comparison of the orientations obtained using these two approaches can be an efficient way to separately determine the orientations of open and cemented fractures.

Processing of seismic data in the presence of anisotropy

Geophysics ◽  
1991 ◽  
Vol 56 (9) ◽  
pp. 1320-1330 ◽  
Author(s):  
Colin MacBeth ◽  
Stuart Crampin
Keyword(s):  
Shear Wave ◽  
Seismic Data ◽  
Shear Waves ◽  
Earth Model ◽  
Seismic Profiling ◽  
Vertical Seismic Profiling ◽  
Full Wave ◽  
Wave Splitting ◽  
Earth Models ◽  
Processing Techniques

Processing techniques for extracting the polarization directions of the fast, and slower split shear waves, together with their traveltime splitting from vector wavefield data, form the basis of prospective procedures for imaging details of the internal structure of subsurface rocks. A recently developed technique involving the independent rotation of the source polarization direction, and geophone axes, provides an effective processing tool for extracting the effects of anisotropy from shear‐wave data. It is theoretically capable of handling nonorthogonal polarization directions of split shear waves. It is further developed, and its performance examined using vertical seismic profiling (VSP) shear‐wave datasets for different anisotropic earth models, and computed using full‐wave modeling. The procedure works well for shear waves propagating through an earth model with a uniform crack strike with depth, but produces inaccurate estimates of polarization and time‐delay when the crack strike varies abruptly with depth. It is unlikely that other techniques could do better under these circumstances, as the problems arise due to the complexities introduced by multiple shear‐wave splitting.

scholarly journals Lorentz force induced shear waves for magnetic resonance elastography applications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guillaume Flé ◽  
Guillaume Gilbert ◽  
Pol Grasland-Mongrain ◽  
Guy Cloutier
Keyword(s):  
Magnetic Resonance ◽  
Shear Wave ◽  
Lorentz Force ◽  
Wave Attenuation ◽  
Shear Waves ◽  
Estimation Method ◽  
Biological Tissues ◽  
Magnetic Resonance Elastography ◽  
Motion Generation ◽  
Wave Source

AbstractQuantitative mechanical properties of biological tissues can be mapped using the shear wave elastography technique. This technology has demonstrated a great potential in various organs but shows a limit due to wave attenuation in biological tissues. An option to overcome the inherent loss in shear wave magnitude along the propagation pathway may be to stimulate tissues closer to regions of interest using alternative motion generation techniques. The present study investigated the feasibility of generating shear waves by applying a Lorentz force directly to tissue mimicking samples for magnetic resonance elastography applications. This was done by combining an electrical current with the strong magnetic field of a clinical MRI scanner. The Local Frequency Estimation method was used to assess the real value of the shear modulus of tested phantoms from Lorentz force induced motion. Finite elements modeling of reported experiments showed a consistent behavior but featured wavelengths larger than measured ones. Results suggest the feasibility of a magnetic resonance elastography technique based on the Lorentz force to produce an shear wave source.

Fracture detection using P-wave and S-wave vertical seismic profiling at The Geysers

Geophysics ◽  
1988 ◽  
Vol 53 (1) ◽  
pp. 76-84 ◽  
Author(s):  
E. L. Majer ◽  
T. V. McEvilly ◽  
F. S. Eastwood ◽  
L. R. Myer
Keyword(s):  
Fractured Rock ◽  
Geothermal Field ◽  
P Wave ◽  
Velocity Variation ◽  
Fracture Detection ◽  
S Wave ◽  
Fracture Geometry ◽  
Seismic Profiling ◽  
Vertical Seismic Profiling ◽  
The Geysers

In a pilot vertical seismic profiling study, P-wave and cross‐polarized S-wave vibrators were used to investigate the potential utility of shear‐wave anisotropy measurements in characterizing a fractured rock mass. The caprock at The Geysers geothermal field was found to exhibit about an 11 percent velocity variation between SH-waves and SV-waves generated by rotating the S-wave vibrator orientation to two orthogonal polarizations for each survey level in the well. The effect is generally consistent with the equivalent anisotropy expected from the known fracture geometry.

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