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

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3

Isotropic Anisotropic

Seismic Anisotropy

Velocities are same in all

directions

Velocities are NOT same in all

directions

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Simple Anisotropic System

Tatham & McCormack, 1991

VTI HTI

Transverse Isotropy Tensor

Voigt notation for VTI system

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Voigt notation for HTI system

Engelder, 2009

Milner, 2010

• Fractures

• Bedding parallel

cracks/ layering

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Anisotropy in the Marcellus Shale

Outcrop

Thin Section and SEM image

Anisotropy Characterization

Lab Measurement data

Borehole Sonic data

Surface Seismic data

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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.

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Future Work

AVOZ

Orthorhombic model

Orientation distribution function with Organic

porosity consideration

Calibration and tie with core and surface seismic

data

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Acknowledgements

EDGER Forum

Dr. Robert H. Tatham

Dr. Kyle Spikes

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Special Thanks to our Sponsors

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