Improving Reservoir Characterization of Karst-Modified Reservoirs with 3-D Geometric Seismic Attributes

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Improving Reservoir Characterization of
Karst-Modified Reservoirs with 3-D Geometric
Seismic Attributes
Susan E. Nissen1, E. Charlotte Sullivan2, Kurt
J. Marfurt3, and Timothy R. Carr4 1Consultant,
McLouth, KS 2Pacific Northwest National Labs,
Richland, WA 3College of Earth and Energy,
University of Oklahoma, Norman, OK 4Department of
Geology and Geography, West Virginia University,
Morgantown, WV
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Outline

• Characteristics of karst-modified reservoirs
• Multi-trace geometric seismic attributes
• Seismic-based examples of
• Collapse structures
• Polygonal features
• Oriented lineaments
• Interpretation workflow for karst-modified
  reservoirs
• Conclusions

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Karst Modified Reservoirs

• Carbonate reservoirs
• Rocks modified by dissolution during subaerial
  exposure
• May also have hydrothermal and tectonic overprints

4
Examples of karst features that can affect
reservoir performance
Collapse features

• Compartmentalize reservoir
• Affect deposition of overlying strata

Cave collapse facies in image log Ft. Worth
Basin, Texas
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Interpretation of Karst Features

• Well data alone is insufficient for identifying
  the spatial extent and distribution of local
  karst features.
• Karst features with substantial vertical relief
  can be readily identified using 3-D seismic.
• Critical features relating to reservoir character
  are often subtle and not readily detected using
  standard 3-D seismic interpretation methods.
• Multi-trace geometric seismic attributes can help!

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Multi-Trace Geometric Seismic Attributes

• Calculated using multiple input seismic traces
  and a small vertical analysis window
• The analysis "box" moves throughout the entire
  data volume gt attributes can be output as a 3-D
  volume
• Provide quantitative information about lateral
  variations in the seismic data

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Multi-Trace Geometric Seismic Attributes

• Coherence - A measure of the trace-to-trace
  similarity of the seismic waveform
• Dip/azimuth - Numerical estimation of the
  instantaneous dip and azimuth of reflectors
• Curvature A measure of the bending of a
  surface (2nd derivative of the surface)

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Mid Continent examples - Collapse structures
- Polygonal features - Oriented lineaments
Central Kansas Uplift
Ord. Arbuckle
Mississippian
Ft. Worth Basin Ord. Ellenburger
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Collapse Features Fort Worth Basin
vertical seismic section
Pennsylvanian Caddo

• Collapse features are visible asdepressions on
  the3-D seismic profile
• Collapse features extend from theEllenburger
  through Pennsylvanian strata

2600 ft
Collapse features
Ordovician Ellenburger
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Attribute time slices near the Ellenburger
Amplitude
Coherence
fault
N
Dip/Azimuth
Most Negative Curvature
Collapse features
E
W
S
3 mi
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Collapse features line up at the intersections of
negative curvature lineaments
Most Negative Curvature
Coherence
Time 1.2 s
1 mi
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Polygonal Features
Ordovician ArbuckleKansas
Ordovician EllenburgerFort Worth Basin
Diameters 700-900 ft
Diameters 1400-1600 ft
Diameters 1200 -3500 ft
Vertical relief generally 2 ms (15 ft) or less
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Arbuckle Polygonal Karst -- Cockpit Karst
doline
cone
Arbuckle structure overlain with paleotopographic
divides in Barton Co., KS (Cansler, 2000)
Morphological map of karst area in New Guinea
(Williams, 1972)
Arbuckle time structure overlain by most positive
curvature
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Ellenburger polygonal karst - tectonic collapse
structures
Faults
Collapse feature at topographic high
Collapse Features Coincide with Deep Basement
Faults
N
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Oriented lineaments -- Kansas Mississippian
Lineament trend vs.oil/water production
0.5 mile
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Workflow for Identification of Karst
OverprintsUsing Multi-Trace Attributes
Interpret features relating to structure,
geomorphology, and reservoir architecture on
attribute slices
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Conclusions

• Coherence, dip/azimuth, and curvature extractions
  are valuable for establishing seismic
  geomorphology
• Different attributes reveal different details
  about karst features
• A workflow utilizing multi-trace attributes,
  along with geologic and production information,
  can improve characterization of karst-modified
  carbonate reservoirs

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Acknowledgements

• Devon Energy
• Grand Mesa Operating Company
• John O. Farmer, Inc.
• Murfin Drilling Company
• IHS - geoPLUS Corporation
• Seismic Micro-Technology, Inc.
• U. S. Department of Energy
• Petroleum Research Fund
• State of Texas ATP
• Kansas Geological Survey, University of Kansas
• University of Houston