Imaging Sand Distribution From Acoustic Impedance

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Imaging Sand Distribution From Acoustic Impedance
Suphan Buri Basin, Central Thailand.
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2
Ronghe, S., and Surarat, K.
1
Dept. Petroleum Geoscience, Universiti Brunei
Darussalam. PTT Exploration and Production PCL.,
Bangkok, Thailand.
2
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CONTENTS

• Study objectives
• Location and geology
• Wireline analysis
• Well to seismic correlation
• Seismic attribute analysis
• Inverse modeling
• Results and interpretation
• Conclusions
• Acknowledgements

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STUDY OBJECTIVES

• To determine the potential of wireline and
  seismic
• as a discriminator of formation lithology
  / fluid.
• To apply the seismic inversion to image
  depositional
• succession

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STUDY LOCATION
Phitsanulok Basin
THAILAND
Mae Ping Fault Zone
Sing Buri Basin
Suphan Buri Basin
STUDY AREA
Ayuthaya Basin
Kamphaeng Saen Basin
Sala Daeng Basin
Three Pagodas Fault Zone
BANGKOK
30 km
Adapted from OLeary and Hill (1989)
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Schematic stratigraphic sequence, Suphan Buri
Basin
Age
Unit
Depositional system
Lithology
Petroleum system
Depth
500 - m
Sands, gravels, siltstone mudstone, fluvial
origin
E
Alluvial - Fluvial
Pliocene - Recent
U
D1
Fluvio-lacustrine sandstone, siltstone interbedded
with mudstone.
D2
1000 -
D3
Reservoirs
Upper
D4
D
D5
Fluvial channel sandstone and conglomeratic
sandstone.
D6
Fluvio- lacustrine
Miocene
Source and Reservoirs
Mid
D7
U
C1
1500 -
Intercalated sandstone, siltstone
mudstone. Lacustrine system with fluvial
influence.
C2
C
Lower
C3
Source
C4
B
Lacustrine
Mudstone with minor siltstone.
Source
Oligocene
Early basin fill Alluvial - lacustrine
Conglomerate, sandstone interbedded with
siltstone and minor mudstone.
2000 -
Source and Reservoirs
A
Basement complex clastics, carbonate rocks or
metasediments.
Pre Tertiary
Adapted from Intharawijitr (1993)
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TWT STRUCTURAL MAP
Time (ms)
Horizon D3
Time structure map
560
630
700
770
840
910
980
1059
Area 37 sq. km.
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Well UT1-7
Well UT1-3
GR
GR
AI
AI
Sub-unit D1
Sub-unit D2
Wireline cross-plots Above OWC
m TVD
m TVD
Sub-unit D3
OWC
OWC
Sub-unit D4
Wireline cross-plots Below OWC
Sub-unit D5
Sub-unit D6
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CONTENTS

• Study objectives
• Location and geology
• Wireline analysis
• Well to seismic correlation
• Seismic attribute analysis
• Inverse modeling
• Results and interpretation
• Conclusions
• Acknowledgements

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Wireline cross-plot Below OWC
UT1-3
High
GR
AI
Shale
Gamma ray (API)
Shaly-sand
Sand
Low
Impedance (g/cc m/s)
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Wireline cross-plot Below OWC
UT1-3
GR
LLD
Gamma ray (API)
Resistivity (ohm / m)
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Wireline cross-plot Above OWC
UT1-7
High
GR
AI
Shale
Gamma ray (API)
Shaly-sand
Sand
Low
Impedance (g/cc m/s)
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Wireline cross-plot Above OWC
UT1-7
GR
LLD
Gamma ray (API)
Resistivity (ohm / m)
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CONTENTS

• Study objectives
• Location and geology
• Wireline analysis
• Well to seismic correlation
• Seismic attribute analysis
• Inverse modeling
• Results and interpretation
• Conclusions
• Acknowledgements

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SEISMIC ATTRIBUTE ANALYSIS
126
OWC
-126
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SEISMIC ATTRIBUTE ANALYSIS
High
OWC
Low
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Well UT1-7
Well UT1-3
GR
GR
AI
AI
Sub-unit D1
Sub-unit D2
Wireline cross-plots Above OWC
m TVD
m TVD
Sub-unit D3
OWC
OWC
Sub-unit D4
Wireline cross-plots Below OWC
Sub-unit D5
Sub-unit D6
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CONTENTS

• Study objectives
• Location and geology
• Wireline analysis
• Well to seismic correlation
• Seismic attribute analysis
• Inverse modeling
• Results and interpretation
• Conclusions
• Acknowledgements

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INVERSE MODELLING FLOWCHART
WAVELETS SEISMIC LOGS
TOPS HORIZONS FAULTS
AI Constraints
AI Interpolation
Solid earth model
CSSI
AI model
Impedance (mid frequency)
Impedance (low frequency)
Trace merge
Final AI result
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IMPEDANCE TREND AND CONSTRAINTS
Well SK-1
Constraints
Trend
AI log
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INVERSE MODELING RESULT
High
Low
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INVERSE MODELING RESULT
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Generalized rift structure and sedimentation
patterns
DELTAIC / FLUVIAL Sandstone mudstone
Fan in footwall transfer zone
ALLUVIAL FAN / FAN DELTA Conglomerate sandstone
(Modified from Leeder and Gawthorpe 1987)
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SUMMARY GEOLOGICAL MODEL OF THE STUDY AREA
Fault linkage
Remnant relay ramp
Minimum displ.
Maximum displacement
Maximum displacement
Fan or slump
Feeder canyons
Axial delta lobe
Axial channel
0
1.5
Basinfloor fans
Km
N
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CONCLUSIONS (1)

• Wireline impedance and seismic attributes
  responded primarily
• to lithology.
• Inverse modeling resulted in good comparison
  between
• wireline impedance and adjacent derived
  impedance traces,
• and enabled vertical sand resolution of
  about 12 m.
• Maximum impedance extractions imaged two
  styles of sand
• distribution axial and boundary fault
  induced deposits.

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CONCLUSIONS (2)

• Axial deposits (delta lobes, channels and
  basinfloor fans)
• prograded from south to north downdip into
  the basin.
• Boundary fault induced deposits (fans /
  slumps and feeder canyons)
• showed two component pathways
• Fans / slumps were transported perpendicular to
  the fault.
• Feeder canyons transported sediment downslope to
  the NE.
• The basin architecture and sedimentation
  patterns agree with
• published general models of rift geology.

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ACKNOWLEDGEMENTS

• PTT Exploration and Production Public Co.
  Ltd.
• for data permission to present the
  results.
• Jason Geosystems and Landmark Graphic Corp.
• for software donation to the Department of
  
• Petroleum Geoscience, UBD.
• Jason Geosystems for technical support and
  review
• of this study.

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PRESENTATION OVERVIEW
Acoustic impedance is used to map the locations
and shapes of sand bodies deposited within a
producing fluvio-lacustrine interval of a
continental half graben basin.