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Selecting Seismic Attributes and Proper Display Parameters . An abridged review of a study conducted on 3-D seismic over Sooner Field, CO By: William C. (Bill) Overman, MS Geophysicist. Slide 2: Sooner Field overview . Lower Cretaceous D-sand Stratagraphic component valley fill sand body

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selecting seismic attributes and proper display parameters

Selecting Seismic Attributes and Proper Display Parameters 

An abridged review of a study conducted on 3-D seismic over Sooner Field, CO

By: William C. (Bill) Overman, MS

Geophysicist

slide 2 sooner field overview
Slide 2: Sooner Field overview
  • Lower Cretaceous D-sand
  • Stratagraphic component
    • valley fill sand body
  • Structural influence critical to trap
  • Significant IPP for the D-J Basin

W.C. Overman, MS, Geophysicist

slide 3 amplitude seismic attribute
Slide 3: Amplitude Seismic Attribute
  • Amplitude from the top of the D sand
  • Strong energy from the sand body
  • Strong energy everywhere else!
  • Does not discriminate prospective vs. back ground

W.C. Overman, MS, Geophysicist

slide 4 peak to trough attribute
Slide 4: Peak to Trough Attribute
  • Anomaly only identifies south half of the sand body
  • Does not present additional drilling opportunities!

W.C. Overman, MS, Geophysicist

slide 5 instantaneous frequency
Slide 5: Instantaneous Frequency
  • Crossline 82 through heart of the sand body
    • Flattened on top of D-sand (black line)
    • Base of D-sand .007 to .009 mils below (heavy red line)
    • Horizon picks cycle through many colors, results in “noisy” attribute maps
  • Frequency range 35 to 85 Hertz
  • Separation of D-sand top and base (isochron) very subtle
  • Separation of frequency bands un-mistakable

W.C. Overman, MS, Geophysicist

slide 6 instantaneous frequency
Slide 6: Instantaneous Frequency
  • Crossline 82 through heart of the sand body
    • Base of D-sand .007 to .009 mils below (heavy red line)
    • Time picks still cycle through white to blue often, “noisy”
  • Frequency range 62 to 64 Hertz
    • All data still present but most frequencies display either white or cyan
  • Separation of D-sand top and base (isochron) very subtle
  • Downward deflection of the white band still obvious

W.C. Overman, MS, Geophysicist

slide 7 d sand isochron map
Slide 7: D-sand Isochron Map
  • Isochron variation from 0.007 to 0.009
    • Variations mapped at below seismic sample rate
    • See full text for discussion
  • Good correlation between isochron and isopach
    • discriminates prospective vs. back ground
  • Extends prospective area to NW, along trend
  • Geometry still does not “look” like a sand body

W.C. Overman, MS, Geophysicist

slide 8 instantaneous frequency from the top of the d sand pick
Slide 8: Instantaneous Frequencyfrom the Top of the D-Sand pick
  • Experimentation showed “best” presentation from 35 and 55 CPS
    • Closest agreement with isopach
    • Least peripheral “noise”
  • All frequencies still present, color for most just set to white
  • Good spatial correlation with isochron map

W.C. Overman, MS, Geophysicist

slide 9 isochron vs frequency
Slide 9: Isochron vs. Frequency
  • Linear relationship of isochron (Slide 7) to frequency (Slide 8).
    • Lower frequencies with longer time
    • Higher frequencies with shorter times
    • Correlation supports validity of sub-sample rate isochron values

W.C. Overman, MS, Geophysicist

slide 10 isochron sweet spots
Slide 10: Isochron “Sweet Spots”
  • Map of narrowly bounded Instantaneous Frequency (62 to 64 Hertz), 4 mils. below the top of the D-sand.
    • Narrow frequency range eliminates most peripheral events.
  • Maps within the isochron and below the “noise” of the D-sand interface (Slides 5 and 6).
  • “Drill the White and avoid the Cyan.” too simple?

W.C. Overman, MS, Geophysicist

slide 11 ipp vs isochron time there is a problem
Slide 11: IPP vs. Isochron Time,there is a problem…
  • Tests assertions vs. real life results!
  • Color map of Initial Production Potential (IPP)
    • Green is the color of $
    • 900+ BOPD NE Sec.21
  • Isochron time contours
    • Contoured from Slide 10

W.C. Overman, MS, Geophysicist

slide 12 ipp vs structure on the d sand top
Slide 12: IPP vs. Structureon the D-sand Top
  • D-sand top depth map, from time structure map.
  • Thick isochron (Slide 11) crosses 40’ low in W ½, Sec. 21.
  • Dry holes were drilled on well control.

W.C. Overman, MS, Geophysicist

conclusions
Conclusions:
  • Peak to Trough attribute could properly locate wildcat
    • High correlation to Instantaneous Frequency in the south
  • Isochron, though subtle, is a valid and useful attribute
    • Good visual correlation to isopach
    • Good numerical correlation to Instantaneous Frequency
    • Valid mapping at sub-seismic sample rate interval
  • Instantaneous Frequency “best” seismic attribute
    • Compact geometry
    • Looks like expected sand body
    • Excellent correlation with isopach thick
    • Suggests field extension along trend

W.C. Overman, MS, Geophysicist

conclusions14
Conclusions:
  • Peripheral “noise” is reduced by:
    • limiting frequency display range
    • selecting time slice within the isochron interval
  • Attribute analysis is not the complete story
    • Geologic fundamentals are critical
    • Analysis driven to find attributes which reflect the known geology
    • Attributes would not find the best IPPs, in sands below seismic resolution.
    • Strong structural influence on IPPs.

W.C. Overman, MS, Geophysicist

conclusions15
Conclusions:
  • Selection of display parameters is critical to analysis
  • Selection of display parameters enhances presentation
    • Limit display to only data values for best dynamic range
    • Display limits can be adjusted so as to:
      • increase visual contrast,
      • blank out visual “noise” without altering the data and/or
      • limit presentation to only features of interest.

W.C. Overman, MS, Geophysicist

acknowledgments
Acknowledgments:
  • Barbara, my wife, for her love and endurance!
  • William C. Cook, Senior Geophysicist, for helpful suggestions upon reviewing the first draft of the full paper.
  • Coerte Voorhies, Sr. Geologist and Account Manager, Seismic Micro Technology, Inc. for his patience with “newbee” questions and his supporting comments regarding this work.
  • Seismic Micro-Technology, Inc., for providing access to The Kingdom Suite of 3D seismic interpretation software, through which this study accomplished.

W.C. Overman, MS, Geophysicist