Seismic properties of unconsolidated sands: Tangential stiffness, Vp/Vs ratios and diagenesis

Avseth, Per; Bachrach, Ran

doi:10.1190/1.2147968

Cited by 15 publications

(7 citation statements)

References 10 publications

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“…Previous southern California imaging studies have observed higher Vp/Vs ratios likely due to greater depth sensitivity (Hauksson, 2000; Lin & Shearer, 2007; G. Lin et al., 2007). The low Vp/Vs ratios obtained in the present model suggest widespread fracturing and/or poor consolidation with little‐to‐no fluid saturation (Avseth & Bachrach, 2005; Bachrach et al., 2000; Shearer, 1988) in the near‐surface crust of Southern California outside of major basins.…”

Section: Discussionmentioning

confidence: 61%

Shallow Crustal Shear Velocity and Vp/Vs Across Southern California: Joint Inversion of Short‐Period Rayleigh Wave Ellipticity, Phase Velocity, and Teleseismic Receiver Functions

Berg

Lin

Schulte-Pelkum

et al. 2021

Geophysical Research Letters

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A primary motivation for these works is the significant seismic hazard posed by the San Andreas fault system, and the related need for physics-based hazard assessment of the region (Graves et al., 2011;Vidale & Helmberger, 1988). For the past 25 years, the Southern California Earthquake Center has developed and maintained multiple Community Velocity Models (CVM) with seismic hazard assessment as one of the explicit goals (

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Section: Discussionmentioning

confidence: 61%

Shallow Crustal Shear Velocity and Vp/Vs Across Southern California: Joint Inversion of Short‐Period Rayleigh Wave Ellipticity, Phase Velocity, and Teleseismic Receiver Functions

Berg

Lin

Schulte-Pelkum

et al. 2021

Geophysical Research Letters

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“…One consequence of the inadequacies of using EMA to describe shear behavior is in the prediction of Poisson's ratio and V P /V S ratio in unconsolidated sands ͑e.g., Avseth and Bachrach, 2005;Sava andHardage, 2006͒. Manificat andGuéguen ͑1998͒ show that a contact roughness model can explain the higher-than-expected Poisson's ratio observed in sands.…”

Section: Introductionmentioning

confidence: 95%

Rock physics modeling of unconsolidated sands: Accounting for nonuniform contacts and heterogeneous stress fields in the effective media approximation with applications to hydrocarbon exploration

Bachrach

Avseth²

2008

GEOPHYSICS

Self Cite

134

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By treating contact stiffness as a variable, one can extend the effective medium approximation used to obtain elastic stiffness of a random pack of spherical grains. More specifically, we suggest calibrating effective media approximation based on contact mechanics by incorporating nonuniform contact models. The simple extension of the theory provides a better fit for many laboratory and field experiments and can provide insight into the micromechanical bonds associated with unconsolidated sediments. This approach is motivated by repeated observations of shear-wave measurements in unconsolidated sands where observed shear-wave velocities are lower than predicted by the Hertz-Mindlin contact theory. We present the calibration process for well-log data from a North Sea well penetrating a shallow-gas discovery and a deepwater well in the Gulf of Mexico. Finally, we demonstrate the benefit of using this model for amplitude variation with angle ͑AVA͒ analysis of shallow sand targets in exploration and reservoir studies.

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“…The ultimate goal of this work is to detect hydrocarbon accumulations, delineate their extent, and calculate their volumes. Therefore, seismic interpretation was based on picking and tracking laterally extended seismic reflectors for mapping geologic and stratigraphic features, and also for determining reservoir architecture 25,[39][40][41] . Petrel software 2017.3 version was used in all geological and geophysical data integration to interpret the seismic data and to generate maps.…”

Section: Seismic Interpretationmentioning

confidence: 99%

“…GR min = Minimum reading of GR in clean interval. We calculated the Vsh% from the GR method using the following non-linear equation: Vsh = 0.33 (2 (2*I GR) -1) used by 39,40 for the early consolidated rocks (Equ. 1).…”

Section: Petrophysical Analysismentioning

confidence: 99%

“…The basic goal of the 3D structural modeling www.nature.com/scientificreports/ is to understand the geological structure in three dimensions 49,50 . The key components required to develop a structural model are interpreting faults and horizons 40 . This framework of horizons and faults also serves as the geometrical input for building the 3D grid and can define the structural model of the AEB reservoirs.…”

Section: Reservoir Modelingmentioning

confidence: 99%

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3D geological and petrophysical modeling of Alam El-Bueib Formation using well logs and seismic data in Matruh Field, northwestern Egypt

Ali,

Deaf,

Mostafa

2024

Sci Rep

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There are several productive petroleum fields in the North Western Desert (WD) of Egypt, which received extensive investigations regarding their petroleum potential. However, a few studies tackled the Matruh Oil Field, which contains the oil prolific Early Cretaceous Alam El-Bueib Formation (AEB Fm) reservoir. The reservoir intervals of the AEB Fm show substantial lithological variations across the basin. Therefore, it is necessary to analyze the vertical and lateral distributions in terms of their lithological and petrophysical properties. To achieve this objective, wireline logs of four wells and 20-2D seismic lines were used to construct a depth-structure contour map for the studied part of the field. This map was used to build the field’s structure model and to identify the fault patterns in the basin through several seismic lines. Analyses of well logs data and lithology were used to estimate the petrophysical properties of AEB sandstone units AEB-1, AEB-3A, AEB-3C, and AEB-6. Results show that the AEB-6 Unit is the most promising hydrocarbon-bearing unit. It has a net pay of 20–160 feet, a shale volume of 5–20%, an effective porosity of 14–20%, and a hydrocarbon saturation of 70–88%. The structure-depth maps indicate a number of normal faults with two principal NE-SW and NW–SE trends, which probably act as structural traps in the Matruh Oil Field. The constructed structure-depth maps and calculated petrophysical parameters were used to build a three-dimensional reservoir model. A blind well was used to validate the accuracy and reliability of the facies, porosity, and saturation models for the AEB Fm units, ensuring a good match between log-derived data and built models. The AEB Fm shows regional heterogeneous variations in its petrophysical characteristics. It exhibits unconventional reservoir characteristics in a N–S direction and conventional reservoir characteristics in an E–W direction. This observed heterogeneity shows the need to carry out further investigations to comprehensively assess the hydrocarbon potential of AEB Fm in different areas of the Matruh Basin.

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Seismic properties of unconsolidated sands: Tangential stiffness, Vp/Vs ratios and diagenesis

Cited by 15 publications

References 10 publications

Shallow Crustal Shear Velocity and Vp/Vs Across Southern California: Joint Inversion of Short‐Period Rayleigh Wave Ellipticity, Phase Velocity, and Teleseismic Receiver Functions

Shallow Crustal Shear Velocity and Vp/Vs Across Southern California: Joint Inversion of Short‐Period Rayleigh Wave Ellipticity, Phase Velocity, and Teleseismic Receiver Functions

Rock physics modeling of unconsolidated sands: Accounting for nonuniform contacts and heterogeneous stress fields in the effective media approximation with applications to hydrocarbon exploration

3D geological and petrophysical modeling of Alam El-Bueib Formation using well logs and seismic data in Matruh Field, northwestern Egypt

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