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Seismic Attr ibutes &

Reservoir Properties

Rovicky Dwi Putrohari

COURSE OUTLINE

• Reservoir Model

• Seismic geology Interpretation

• Extracting Stratigraphic from

seismic• Seismic Attr ibutes & Reservoir 

Properties

• Reservoir Modeling for ProspectScale

• Exercises

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Seismic Attributes

Seismic attributes may be defined as “all theinformation obtained from seismic data, either bydirect measurements or by logical or experiencebased reasoning.”(Taner, 1998)

•Physical Attribute

– Relate to wave propagation, lithology and otherphysical parameter

•Geometrical Attribute– Geometric attributes describe the spatial and

temporal relationship of all other attributes.

Factor affecting Amplitude

1. Acquisition

2. Processing

3. Post Processing

See Sheriff,

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Factor influencing seismic of sedimentary rocks

Wang, 2001

Well and Seismic Ties

Well data Seismic data

     D    e    p     t     h

     T     i    m    e

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Seismic Trace

*

AI(t) RC(t) W(t) S(t)

WAVELET

Acoustic Impedance Inversion

SeismicAcquisition

Earth * Wavelet = Seismic

Seismic / Wavelet = AI

SeismicInversion

AI Earth

ReservoirModeling/Characterization

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 Acoustic impedance Section(Band Limited AI)

- 0 +

 Acoustic impedance Section(Final AI)

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 Amplitude Section

Impedance Section

LOW

IMPEDANCE

HIGH

IMPEDANCE

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Extracting Attribute

TW Time Horizon Pick

 Attr ibute

Extraction

TW Time Horizon Pick

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Extraction

 Attr ibute

Display Impedance Section

MAIN

HORIZONS

GR

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Interprete Stratigraphy

TOP SET

TOP SET

TOP SETMAIN

HORIZONS

GR

Define Reservoir Geometry

TOP SET

TOP SET

TOP SET

PARASEQUENCE

GR

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Reservoir Properties from Seismic

Earth Seismic AI Earth

Seismic

 Acquis it ion

Earth * Wavelet = Seismic

Seismic / Wavelet = AI

Seismic

Inversion

AI Earth

Reservoir 

Modeling

Seismic Modeling

Forward Modeling Inverse Modeling

Input

Process

Output

Earth

Model

Modeling

 Algorithm

Seismic

Response

Seismic

Response

Inversion

 Algorithm

Earth

Model

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Why use AI ?

• Lithology

• Porosity

• Fluid Content

• Depth

• Pressure (over pressure, AI drops)

Well versus Seismic AI

• Well Acoust ic Impedance :

• AI Log = Density Log x Velocity Log

• Fine vertical sampling

• Seismic Acoustic Impedance :

• Derived by Seismic Inversion

• Good lateral sampling

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 AI data can be used as a :

• Lithology Indicator & Map lithology

• Porosity indicator

• Hydrocarbon indicator

• Tool for quantitative analysis

 AI and RC

Density (ρ) and velocity (V) :

 AI = ρ . V = g/cc . ft/s

 AI1

 AI2

 AI3

RC 1 =

RC 2

 AI2 - AI1

 AI2 + AI1

- +

RC =Reflection Coefficient

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 Amplitude – Acoustic Impedance

Seismic Amplitude

♦ Bondary properties

Acoustic Impedance

♦ Internal propreties

 AI on Well

Oil Sand Water Sand

Shale

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 AI on SeismicINTERPRETATION PROBLEM

INTERPRETATION PROBLEM AI provide easier (visual) correlat ion/interpretation

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INTERPRETATION PROBLEM AI provide easier (visual) correlat ion/interpretation

Porosity from seismic vs well

Seismic driven porosity profile

Seismic driven porosity map

Well driven porosity profile

Well driven porosity map

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Porosity from seismic and well

Frequency-merged driven porosity profile

Frequency-merged driven porosity map

Porosity from seismic and well

Seismic driven porosity profile

Seismic driven porosity map

Well driven porosity profile

Well driven porosity map

Frequency-merged driven porosity profile

Frequency-merged driven porosity map

Seismic only Well only Well and seismic

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Benefits of Using Acoustic Impedance

• Quantitative predictions of reservoirproperties

• Easier to interpret horizons, faults,stratigraphic units

• Easy to understand by non-geoscientist

• Great integration tool• Compare directly to wells

Quantitative use of AI

• AI can be used to derive rockproperties, such as :

– lithology,

– porosity,

– fluid contents

• Absolute AI can be used for quantitativereservoir characterization

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Seismic

 Acquis it ion

Earth * Wavelet = Seismic

Seismic / Wavelet = AI

Seismic

Inversion

AI Earth

Reservoir 

Modeling

Reservoir Properties from Seismic

Earth Seismic AI Earth