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Characterization of Seismic
Anisotropy of the Marcellus Shale
from Borehole Data
Sharif Morshed
Ph.D. Aspirant
1
Advisor : Dr. Robert Tatham
Talk Outline
Seismic Anisotropy : Theoretical Basics
Dipole Sonic Tool
Anisotropy Characterization The Marcellus Shale Data
VTI Analysis
Backus Average
HTI Analysis
Fracture Modeling
Conclusion
Future Work
2
3
Isotropic Anisotropic
Seismic Anisotropy
Velocities are same in all
directions
Velocities are NOT same in all
directions
4
Simple Anisotropic System
Tatham & McCormack, 1991
VTI HTI
Transverse Isotropy Tensor
Voigt notation for VTI system
5
Voigt notation for HTI system
Engelder, 2009
Milner, 2010
• Fractures
• Bedding parallel
cracks/ layering
6
Anisotropy in the Marcellus Shale
Outcrop
Thin Section and SEM image
Anisotropy Characterization
Lab Measurement data
Borehole Sonic data
Surface Seismic data
7
Velocities from Borehole Sonic Data
Compressional and Shear slowness
Monopole Source (7-20kHz)--Vp(0o), Vs(0o)
Shear Slowness Fast and Slow
Dipole Source (2-4kHz)—Vs1,Vs2
Stoneley Slowness
Horizontal Shear wave slowness
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Dipole Sonic Tool
Shear Slowness Fast and Slow
Dipole Source (2-4kHz)—Vs1,Vs2
-> Estimate of C44, C55
Zemanek et al, 1991 Brie et al, 1998
Anisotropy (ϒ) 10
The Marcellus Shale
Middle Devonian marine organic shale extensive in New York,
Pennsylvania, Ohio and West Virginia
• For VTI, Thomsen (1986) parameters
C33=ρ(Vp(0o))2
C44=C55=ρ(Vs(0o))2
C66=ρ(Vs(90o))2
C11=?, C13=?, Ɛ=?, δ=?
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Estimation of VTI Anisotropic parameter
from Dipole log
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Thomsen (1986) ϒ from Monopole log
0 0.05 0.1 0.15 0.2 0.25 0.30
20
40
60
80
100
120
Thomsen Gamma
Co
un
t
C44--Vertical monopole shear slowness C66--Horizontal shear slowness from stoneley slowness
VTI Anisotropy at Seismic Scale
Upscaling
Seismic frequency--~order of 10’s, like 50 Hz
Borehole monopole frequency--~ 5-10kHz
Borehole dipole frequency -- ~ 2 kHz
Backus (1962) Average
a. Upscaling at seismic wavelength
b. Full VTI tensor
c. Estimation of Ɛ, γ, and δ
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Thomsen parameters from Backus (1962)
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-0.01 -0.005 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04
8340
8360
8380
8400
8420
8440
8460
8480
8500
8520
Thomsen (1986) Parameter
De
pth
(ft
)
Epsilon
Gamma
DeltaUpper
Marcellus
Lower
Marcellus
Averaging
Length= 20 ft
Ɛ ϒ δ
Upper Marcellus 0.0052 0.0071 -0.0012
Lower Marcellus 0.0029 0.0033 -0.0001
Total Marcellus 0.0065 0.0086 -0.0014
Upscaled Velocities using Backus (1962)
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HTI Anisotropy
Voigt notation for stiffness
tensor of HTI system
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C44=ρ(Vs2)2
C66=C55=ρ(Vs1)2
Average Wave length ~ 3.5 ft
Fracture Modeling
Hudson (1982) for isolated
penny shaped cracks,
𝑐𝑖𝑗𝑒𝑓𝑓
= 𝑐𝑖𝑗0 + 𝑐𝑖𝑗
1 + 𝑐𝑖𝑗2
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0 0.01 0.02 0.03 0.04 0.05 0.060
2
4
6
8
10
12
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Crack Induced Porosity
Co
un
t
Aspect ratio : 0.07 - 0.15
Crack density : 0.005-0.09
First Order correction for
dry cracks
Fracture Modeling Results
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Dry cracks are substituted with Gas, Using Gassmann (1951)
Conclusion
• The Marcellus shale is complex in terms
of anisotropy.
• The Marcellus Shale is very weakly VTI at
seismic frequency.
• The Marcellus shale may be fractured.
• More complex model like Orthorhombic
consideration may give better result.
19
Future Work
AVOZ
Orthorhombic model
Orientation distribution function with Organic
porosity consideration
Calibration and tie with core and surface seismic
data
20
Acknowledgements
EDGER Forum
Dr. Robert H. Tatham
Dr. Kyle Spikes
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Special Thanks to our Sponsors
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