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Nissen karst brilliant

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Nissen karst brilliant

  1. 1. Improving Reservoir Characterization of Karst-Modified Reservoirswith 3-D Geometric Seismic Attributes Susan E. Nissen1, E. Charlotte Sullivan2, Kurt J. Marfurt3, and Timothy R. Carr4 1 Consultant, McLouth, KS Pacific Northwest National Labs, Richland, WA 2College of Earth and Energy, University of Oklahoma, Norman, OK34 Department of Geology and Geography, West Virginia University, Morgantown, WV
  2. 2. 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
  3. 3. Karst Modified Reservoirs• Carbonate reservoirs• Rocks modified by dissolution during subaerial exposure• May also have hydrothermal and tectonic overprints
  4. 4. Examples of karst features that can affect reservoir performance Collapse features Residual Solution-enlarged• Compartmentalize paleo-highs fractures reservoir • May be hydro- • Fluid conduits (if• Affect deposition carbon traps open) or barriers of overlying strata (if filled) Loess-filled fractures, Missouri Cockpit karst, JamaicaCave collapse facies in image log www.cockpitcountry.com Ft. Worth Basin, Texas
  5. 5. 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!
  6. 6. 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 => attributes can be output as a 3- D volume• Provide quantitative information about lateral variations in the seismic data
  7. 7. Multi-Trace Geometric Seismic Attributes• Coherence - A measure of the trace-to-trace similarity of the seismic waveform Reference Trace• Dip/azimuth - Numerical estimation of the Instantaneous dip = Dip with highest instantaneous dip and coherence azimuth of reflectors Dips tested• Curvature – A measure of the Positive Curvature bending of a surface (~2nd Cu Zer rv o atu Zero Curvature derivative of the surface) re Negative Anticline Curvature Di p X Pl pin R Flat an g e Syncline Z Curvature (k)=1/R After Roberts, 2001
  8. 8. Mid Continent examples Central Kansas Uplift Ord. Arbuckle - Collapse structuresMississippian - Polygonal features - Oriented lineaments Ft. Worth Basin Ord. Ellenburger
  9. 9. Collapse Features – Fort Worth Basin vertical seismic section Pennsylvanian Caddo • Collapse features are visible as depressions on the~2600 ft 3-D seismic profile Collapse features • Collapse features extend from the Ellenburger through Pennsylvanian strata Ordovician Ellenburger
  10. 10. Attribute time slices near the Ellenburger Amplitude Coherence fault N Dip/Azimuth Most Negative CurvatureW E Collapse S features 3 mi
  11. 11. Collapse features line up at the intersections of negative curvature lineaments Coherence Most Negative CurvatureTime = 1.2 s 1 mi
  12. 12. Polygonal Features Ordovician Arbuckle Ordovician Ellenburger Kansas Fort Worth Basin 1 mi 1 mi 1 mi 1.6 km 1.6 km 1.6 kmDiameters ~700-900 ft Diameters ~1400-1600 ft Diameters ~1200 -3500 ft Vertical relief generally 2 ms (~15 ft) or less
  13. 13. Cockpit Cockpits karst Arbuckle Polygonal Karst -- Cockpit Karst (After Cansler and Carr, 2001)doline cone 1 m i 1 .6 k m Morphological map Arbuckle structure overlain Arbuckle time structure with paleotopographic of karst area in New overlain by most positive divides in Barton Co., KS Guinea (Williams, curvature (Cansler, 2000) 1972)
  14. 14. Ellenburger polygonal karst - tectonic collapse structuresCollapse feature Faultsat topographic high Collapse Features Coincide with Deep Basement Faults N Ellenburger Basement
  15. 15. Oriented lineaments -- Kansas Mississippian Lineament trend vs. oil/water production 14 100 90 12 5 year water production (x104 Bbl) 5 year oil production (x104 Bbl) 80 10 70 60 8 50 6 40 30 4 20 2 10 0 0 0 100 200 300 400 500 600 700 800 0 100 200 300 400 500 600 700 800 distance to NE lineament (ft) distance to NE lineament (ft) 14 100 90 12 5 year water production (x10 Bbl) 5 year oil production (x104 Bbl) 80 4 10 70 60 8 50 6 40 4 30 20 2 10 0 0 0 100 200 300 400 500 600 700 800 0 100 200 300 400 500 600 700 800 0.5 mile distance to NW lineament (ft) distance to NW lineament (ft)
  16. 16. Workflow for Identification of Karst Overprints Using Multi-Trace Attributes Interpret features relating to Extract attributes structure, geomorphology,Volumetric along horizon and reservoir architectureattributes or time slice on attribute slices Identify dominant karst Predict general production Horizon geomorphology (e.g., polygonal performance based on picks karst vs. groundwater-sapped type of karst overprint plateaus)Core and Separate subaerial karst Identify areas oflog data from tectonic overprint enhanced or occluded porosity/permeability Measure distance from oriented lineaments. Outline potential reservoirProduction Identify preferred orientations compartment boundaries data of fluid conduits vs. barriers (fluid barriers)
  17. 17. 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
  18. 18. 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

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