Fracture effects in seismic attenuation images reconstructed by waveform tomography

Geophysics ◽  
2009 ◽  
Vol 74 (4) ◽  
pp. R25-R34 ◽  
Author(s):  
Ying Rao ◽  
Yanghua Wang
Keyword(s):  
Petroleum Reservoirs ◽  
Seismic Attenuation ◽  
Fracture Density ◽  
Seismic Reflection Data ◽  
Fracture Angle ◽  
Reflection Data ◽  
Seismic Waveform ◽  
Half Wavelength ◽  
Waveform Tomography ◽  
Domain Inversion

We have investigated seismic waveform tomography to characterize fractures in petroleum reservoirs. Seismic reflection data are used in a frequency-domain inversion to reconstruct subsurface attenuation images. The images show fracture distributions, from which fracture density is estimated. Fractures smaller than or equal to a half-wavelength of seismic act as single scatterers, producing images of strong attenuation ellipses and from which fracture density can be estimated. When fracture size approaches one wavelength, fracture orientation affects the attenuation image. Horizontal fractures act as individual reflectors and produce strong tomographic attenuation images from which fracture density can be estimated. The strength of the attenuation image decreases when the fracture angle relative to horizontal increases; vertical fractures produce the weakest attenuation image. Consequently, the accuracy of fracture density measurements decreases with increased fracture angle unless waveform tomography includes different seismic modes acquired from several directions.

Detecting near-surface objects with seismic waveform tomography

Geophysics ◽  
2009 ◽  
Vol 74 (6) ◽  
pp. WCC119-WCC127 ◽  
Author(s):  
Brendan Smithyman ◽  
R. Gerhard Pratt ◽  
John Hayles ◽  
Ralph Wittebolle
Keyword(s):  
Seismic Attenuation ◽  
Blind Test ◽  
Near Surface ◽  
Traveltime Tomography ◽  
Seismic Waveform ◽  
Long Offset ◽  
Velocity Images ◽  
Weight Drop ◽  
Waveform Tomography ◽  
Geophysical Imaging

Three shallow, high-velocity, rubble-filled targets are imaged using waveform tomography in an engineering-scale clay embankment at Seven Sisters Falls, Manitoba, Canada, to locate targets buried at approximately [Formula: see text] as a blind test of geophysical imaging methods. Previous studies use near-offset reflection methods to image the targets; however, this test uses waveform tomography of the long-offset, refracted arrivals to image P-velocity and seismic attenuation. The targets are invisible to standard traveltime tomography. Using weight-drop data, with frequencies of 20–150 Hz, the subwavelength targets are resolved in the velocity images and complementary images of seismic [Formula: see text] are produced. The interpreted target locations are consistent with limited survey information from the embankment construction. Multiple quality-control efforts, paired with a very good fit between model and observed data, indicate the reliability of the results.

Application of waveform tomography to marine seismic reflection data from the Queen Charlotte Basin of western Canada

Geophysics ◽  
2011 ◽  
Vol 76 (2) ◽  
pp. B55-B70 ◽  
Author(s):  
E. M. Takam Takougang ◽  
A. J. Calvert
Keyword(s):  
Seismic Reflection ◽  
Field Data ◽  
Velocity Model ◽  
P Wave ◽  
Low Velocity ◽  
Seismic Line ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Sonic Log ◽  
Waveform Tomography

To obtain a higher resolution quantitative P-wave velocity model, 2D waveform tomography was applied to seismic reflection data from the Queen Charlotte sedimentary basin off the west coast of Canada. The forward modeling and inversion were implemented in the frequency domain using the visco-acoustic wave equation. Field data preconditioning consisted of f-k filtering, 2D amplitude scaling, shot-to-shot amplitude balancing, and time windowing. The field data were inverted between 7 and 13.66 Hz, with attenuation introduced for frequencies ≥ 10.5 Hz to improve the final velocity model; two different approaches to sampling the frequencies were evaluated. The limited maximum offset of the marine data (3770 m) and the relatively high starting frequency (7 Hz) were the main challenges encountered during the inversion. An inversion strategy that successively recovered shallow-to-deep structures was designed to mitigate these issues. The inclusion of later arrivals in the waveform tomography resulted in a velocity model that extends to a depth of approximately 1200 m, twice the maximum depth of ray coverage in the ray-based tomography. Overall, there is a good agreement between the velocity model and a sonic log from a well on the seismic line, as well as between modeled shot gathers and field data. Anomalous zones of low velocity in the model correspond to previously identified faults or their upward continuation into the shallow Pliocene section where they are not readily identifiable in the conventional migration.

An example of the measurement and practical applications of time-lapse seismic attenuation

Geophysics ◽  
2015 ◽  
Vol 80 (2) ◽  
pp. WA25-WA34 ◽  
Author(s):  
Thomas D. Blanchard ◽  
Pauline Delommot
Keyword(s):  
Coming Out ◽  
Water Injection ◽  
Time Lapse ◽  
Seismic Attenuation ◽  
Data Sets ◽  
Seismic Reflection Data ◽  
Practical Applications ◽  
Reflection Data ◽  
Underlying Mechanisms ◽  
Text Correction

There is much theoretical and laboratory evidence for fluid-related mechanisms causing attenuation in the seismic bandwidth; however, the number of measurements made from seismic reflection data is limited. We measured attenuation changes in a reservoir undergoing depletion and, in some locations, water injection. Two different applications of these measurements were then found. First, we used the measured attenuation changes to perform a time-lapse [Formula: see text] correction to improve 4D inversion results in an underlying reservoir. Second, we attempted to integrate the measured attenuation changes with changes in traveltime to try to separate gas and water saturations in the reservoir. We determined that large and coherent time-lapse attenuation measurements can occur in reservoirs undergoing production and that the nature of this attenuation when averaged across a region of the reservoir was consistent with a constant-[Formula: see text] hypothesis. Measurements were of good quality and were coherent with the geologic (such as channels) and dynamic characteristics (such as gas coming out of solution) of the reservoir. Finally, we evaluated the possible implications of such data sets upon enhancing our understanding of the underlying mechanisms controlling attenuation in the seismic bandwidth by providing favorable conditions for canceling spectral contamination and the fact that we have knowledge of the physical changes occurring within the reservoir.

Estimation of seismic quality factor in the time-frequency domain using variational mode decomposition

Geophysics ◽  
2020 ◽  
Vol 85 (4) ◽  
pp. V329-V343
Author(s):  
Ya-Juan Xue ◽  
Jun-Xing Cao ◽  
Xing-Jian Wang ◽  
Hao-Kun Du
Keyword(s):  
Quality Factor ◽  
Seismic Reflection ◽  
Seismic Attenuation ◽  
Reflection Coefficients ◽  
Variational Mode Decomposition ◽  
Seismic Reflection Data ◽  
Time Frequency ◽  
Reflection Data ◽  
Mode Decomposition ◽  
Seismic Quality Factor

Seismic attenuation as represented by the seismic quality factor [Formula: see text] has a substantial impact on seismic reflection data. To effectively eliminate the interference of reflection coefficients for [Formula: see text] estimation, a new method is proposed based on the stationary convolutional model of a seismic trace using variational mode decomposition (VMD). VMD is conducted on the logarithmic spectra extracted from the time-frequency distribution of the seismic reflection data generated from the generalized S transform. For the intrinsic mode functions after VMD, mutual information and correlation analysis are used to reconstruct the signals, which effectively eliminates the influence of the reflection coefficients. The difference between the two reconstructed logarithmic spectra within the selected frequency band produces a better linear property, and it is more suitably approximated with the linear function compared to the conventional spectral-ratio method. Least-squares fitting is finally applied for [Formula: see text] estimation. Application of this method to synthetic and real data examples demonstrates the stabilization and accuracy for [Formula: see text] estimation.

The style of transverse faulting in the Dead Sea basin from seismic reflection data: The Amazyahu fault

2006 ◽  
Vol 55 (3) ◽  
pp. 129-139 ◽  
Author(s):  
Avihu Ginzburg ◽  
Moshe Reshef ◽  
Zvi Ben-Avraham ◽  
Uri Schattner
Keyword(s):  
Seismic Reflection ◽  
Dead Sea ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Dead Sea Basin ◽  
The Dead

Archive of digital boomer seismic reflection data collected offshore east-central Florida during USGS cruise 00FGS01, July 14-22, 2000

Data Series ◽  
10.3133/ds496 ◽  
2009 ◽  
Author(s):  
Janice A. Subino ◽  
Shawn V. Dadisman ◽  
Dana S. Wiese ◽  
Karynna Calderon ◽  
Daniel C. Phelps
Keyword(s):  
Seismic Reflection ◽  
Seismic Reflection Data ◽  
East Central ◽  
Central Florida ◽  
Reflection Data
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