Anticipated seismic response of the Bakken shale Devonian, East Williston Basin, North Dakota

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Anticipated seismic response of the Bakken shale
(Devonian), East Williston Basin, North Dakota

• Fang (Fiona) Ye
• Robert H. Tatham
• Eric von Lunen

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Outline

• Introduction
• Objective
• Well log analysis
• Preliminary seismic modeling results
• Summary
• Future work
• Acknowledgements

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Introduction
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• The Bakken Formation
• 3.0-4.3 BBO
• Williston Basin,
• North Dakota
• Upper Devonian
• Lower Mississippian
• Upper Bakken
• Middle Bakken
• Lower Bakken

USGS
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Objective
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Objective
Identify seismically observable characteristics
of the Bakken Shale associated with the
productivity

• Seismic
• Data(3D3C)
• Orientation of anisotropy
• Degree of anisotropy
• AVO

• Well Log Data
• Depth
• Thickness
• Density
• Vp
• Vs

• Seismic
• Modeling
• Isotropic
• Anisotropic-VTI
• Anisotropic-HTI

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Objective
Identify seismically observable characteristics
of the Bakken Shale associated with the
productivity

• Seismic
• Data(3D3C)
• Orientation of anisotropy
• Degree of anisotropy
• AVO

• Well Log Data
• Depth
• Thickness
• Density
• Vp
• Vs

• Seismic
• Modeling
• Isotropic
• Anisotropic-VTI
• Anisotropic-HTI

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Well log analysis
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Depth and thickness
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Density
Upper Bakken Shale
Middle Bakken
Lower Bakken Shale
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Density

• Average Density (gm/cc)
• Upper Bakken Shale 2.24
• Middle Bakken 2.62
• Lower Bakken Shale 2.24

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Vp Vs
Upper Bakken Shale
Middle Bakken
Lower Bakken Shale
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P-wave and S-wave
Velocity

• Bakken Shales Low P and S velocity
• Vp 9500ft/s
• Vs 5700ft/s
• Middle Bakken
• Vp 16000ft/s
• Vs 9400ft/s

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Vp / Vs
Upper Bakken Shale
Middle Bakken
Lower Bakken Shale
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Vp / Vs

• Bakken Shale Low Vp/Vs

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Youngs Modulus and Poissons Ratio
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Preliminary seismic modeling results
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Modeling Step 1 Isotropic
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Isotropic, explosive source
P-P
P-P
P-SV
P-SV
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Isotropic, vertical point source
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Anisotropic Model

• VTI

• HTI

Schlumberger
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Modeling Step 2 Anisotropic-VTI
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Anisotropic - VTI
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Difference between VTI Isotropic
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Summary
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Summary

• The Upper and Lower Bakken shales are
  characterized by very low density and very low P
  and S wave velocities.
• The Middle Bakken may be considered as isotropic.
  The Upper and Lower Bakken shales are
  anisotropic.
• Preliminary seismic modeling results show that
  the seismic responses are different for isotropic
  model and anisotropic model of the Bakken
  Formation.

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Future work
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Future work

• AVO analysis
• HTI and TTI
• Different wells
• Anisotropy analysis for seismic data based on
  modeling results

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Acknowledgements
Robert H. Tatham Mrinal K. Sen Eric von
Lunen Samik Sil
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Thank You