Download - Seismic attributes of the Barnett and Bakken shales

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Bode Omoboya

16th May, 2013

Seismic attributes of the Barnett and Bakken shales

Introduction

Bakken Shale Case Study

Barnett Shale Case Study

Other Forward Modeling Projects

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VTI Anisotropy

Isotropic or HTI AnisotropyDue Open

Vertical Fractures

VTI Anisotropy

Geologic Age Upper Devonian/Lower Miss

Lithology (Middle Member)

Sandstone/Siltstone/Dolomite

Total Area (sq mi) 200000Total Gas (tcf) 945Producable Gas (tcf) 20Depth (feet) 10000Thickness (feet) 150Pressure (psi) 5600Porosity (%) 5Matrix Permeability (nD)

10000

Pressure Gradient (psi/ft)

0.5

Clay Content (Middle Member %)

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Average Horz Well Cost ($M)

5.5Most oil in the Bakken petroleum system resides in open fractures in the Middle Member (Pitman et al, 2001). Source: USGS

Bakken Shale Quick Facts

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MD= 9100 ft

MD= 9250 ft

Well: NELSON

Upper Shale

Middle Member

Lower Shale

Core Image from NDIC

Bakken Shale – Core Samples and Well Logs

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𝐼𝐺𝑅=𝐺𝑅 𝑙𝑜𝑔−𝐺𝑅𝑚𝑖𝑛

𝐺𝑅𝑚𝑎𝑥−𝐺𝑅𝑚𝑖𝑛

1000 ft. Interval40% – 60% Vsh

200 ft. Interval80% Vsh

𝑉 h𝑠 =𝐼𝐺𝑅

3−2 𝐼𝐺𝑅

Steiber, 1970

Bakken Shale – Shale Volume

Data Courtesy of Hess Corporation

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X/D=14500ft (offset)

V=3000ft/s

V=16000ft/s

t=700 ms

t=1800 ms X= 0 ft X= 15000

ft

Bakken Shale – Non-Hyperbolic Moveout

C11 C33 C44 C66 C13 e g d

343 227 54 106 107 0.255 0.481 -0.051

from Core = 0.341

from Seismic ≈ 0.32

Jones and Wang, 1981

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Bakken Shale – Forward Modeling Project

Physical modeling of anisotropic domains: Ultrasonic imaging of laser-etched fractures in glass(Geophysics, 2013 )Robert. R. StewartNikolay DyaurBode OmoboyaJ.J.S de FigueiredoMark WillisSamik Sil

Before Post-stack Migration

After Post-stack Migration

Model C1

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Minimum Offset 400mMaximum Offset 2000mCMP Interval 20mDepth of Model 800m ( TWT to end of model =

350ms)Average Velocity of Model 5800m/sDominant Frequency/ Wavelength

120 Hz / 50m

Model C3

Model C10

Model C9“BAKKEN MODEL”

Schematic of NMO eta scan experiments on glass models


Model C3Max = 0.0𝞰Blank Model

Model C10Max = 0.23𝞰VTI Model

Model C9 Azimuth 0Max = 0.14𝞰VTI+HTI+VTI

Model C9 Azimuth 45Max = 0.08𝞰VTI+HTI+VTI

Model C9 Azimuth 90Max = -0.06𝞰VTI+HTI+VTI

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25

Max 𝞰𝞰

Model C3Blank Model

Model C10VTI Model

Model C9Azimuth 0

Model C9Azimuth 45

Model C9Azimuth 90

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𝞰= -0.3

𝞰= 0.3

𝞰= -0.3

𝞰= 0.3

t = 350 ms

t = 350 ms

t = 350 ms

t = 350 ms

t = 350 ms


Barnett Shale Quick Facts

N-S structural cross section through the Newark Field in the Fort Worth Basin. Modified after Burna and Smosna, 2011

Geologic Age Mississipian

Lithology Dense Organic rich shale

Water Saturation((clay-bound)

20-30%

Gas Saturation 70-80%

Depth (feet) 4000 - 5000

Thickness (feet) 5-1000 ft

Pressure (psi) 5600

Porosity (%) 5

Natural fractures 100 to 120 deg

Natural fractures More common in limestone interbeds

Artificial fractures Oriented in the direction of minimal stress

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Barnett Shale – Top Ellenberger – Maximum Curvature Attribute

Well XWell Y

Data Courtesy of Marathon Oil

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Barnett Shale – CDP Gathers after Time Processing and Migration

Barnett Shale – Migrated Stack + FXY Decon

t = 0s

t = 1.5s

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Barnett Shale – Residual eta (h) Volume

t = 0s

t = 1.5s

h = -0.2

h = 0.2

Barnett Shale – Seismic to well tie

Well Y

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P-Impedance Volumet = 0.55ms

t = 0.85ms

Base Marble Falls

Top Barnett

Top Ellenberger

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Density Volumet = 0.55ms

t = 0.85ms

Base Marble Falls

Top Barnett

Top Ellenberger

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Mu-Rho Volumet = 0.55ms

t = 0.85ms

Base Marble Falls

Top Barnett

Top Ellenberger

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Barnett Shale – Forward Modeling Project

Constituent Materials:

• Resin• Plexiglass

(polycarbonate)• Copper tubes

Experimental study of the influence of fluids on seismic azimuthal anisotropy.(Geophysical Prospecting, 2013, submitted, under review)Bode OmoboyaEmrah PacalJ.J.S de FigueiredoNikolay DyaurRobert. R. Stewart

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Vs

(Z)

m/s

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C11 C33 C33 C44 C550

5

10Water Saturated

Laboratory MeasuredGassmann Predicted

Stiff

ness

Coe

f-

ficie

nt (

GPa

)

C11 C33 C33 C44 C550

4

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Glycerin SaturatedLaboratory MeasuredGassmann Predicted

Stiff

ness

Coe

f-

ficie

nt (

Gpa

)

C11 C33 C13 C44 C55

C11 C33 C13 C44 C55


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Model M2Crack Density = 4.5 %

Model M3Crack Density = 4.0 %

Model M1Reference Model

Hudson, 1981

ɛ =

Shear wave anisotropy from aligned inclusions: ultrasonic frequency dependence of velocity and attenuation(Geophysical Journal International, 2013)J.J.S de FigueiredoNikolay DyaurBode OmoboyaRobert. R. Stewart

Forward Modeling Examples: Source Frequency VS Anisotropy

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ϒ=12 (𝑉 𝑠1

2

𝑉 𝑠22 − 1 )

Thomsen, 1986

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Dr. Steve Peterson – Marathon OilMichelle Simon – Hess CorporationDr. Edip Baysal – Paradigm Schlumberger (For VISTA Processing

Software)

Acknowledgement