Testing survey resolution using

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Testing survey resolution using Spectral
Analysis Authors Markham, S.L., Kivior, I.,
Vaughan, F.V., Yates, S. and Barnden S. EAGE
Workshop on The Future of Non-Seismic
Methods 12-15 October 2008, Manama, Bahrain
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Table of Contents
Introduction Theoretical Models One layer Two
layer Case Study Central San Luis Basin MWT
examples Conclusions
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Theoretical Models One and Two Layers One
Layer 50x50m, 100x100m and 500x500m grid
spacing Two Layers 100x100m, 200x200m and
500x500m grid spacing
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One layer model Basement
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Profile view of one layer model

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Simple one layer model Basement at 1km and 5km

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MWT plots for 50x50m grid
Manual Multi-Window Test Grid Resolution 50x50m
Source Depth 1km

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30
50
70
90
0
500
Depth m
1000
Window Size
1500
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MWT plot for 50x50m grid, source depth 5km

5000m
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Simple one layer model Basement at 1km and 5km

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MWT plots for 500x500m grid, source depth 1km

1000m
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MWT plot for 500x500m grid, source depth 5km

5000m
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Two layer model Sedimentary layer

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Profile view of 2 layer model

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Two layer model 100x100m grid, source depths 1
2km

1000m
2000m
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Two layer model 100x100m grid, source depths 4
5km

4000m
5000m
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Two layer model 200x200m grid, source depths 1
2km

1000m
2000m
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Two layer model 200x200m grid, source depths 4
5km

4000m
5000m
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Two layer model 500x500m grid, source depths 1
2km

1000m
2000m
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Two layer model 500x500m grid, source depths 1
2km

1000m
2000m
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Two layer model 500x500m grid, source depths 4
5km

4000m
5000m
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Case study using survey acquired on behalf of
USGS in Central San Luis Basin, Colorado, U.S.A.
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Central San Luis Basin survey (USGS) Examples
using the 200m line spacing dataset (40x40m
grid) Traverse lines removed to simulate 400m
line spacing (80x80m grid) 800m line spacing
(160x160m grid) 2000m line spacing (400x400m
grid)
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Location of test area

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Location of MWT profile and manual stations

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2
3
4
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MWT Auto-ESA (40x40m)

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MWT Depth vs. Window Size at 4 points along
profile (40x40m)
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1

3
4
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MWT Example of spectrum at 417000mE (2)

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MWT Auto-ESA (80x80m)

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MWT Depth vs. Window Size at 4 points along
profile (80x80m)
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2

4
3
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MWT Auto-ESA (160x160m)

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MWT Depth vs. Window Size at 4 points along
profile (160x160m)
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2

4
3
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MWT Auto-ESA (400x400m)

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MWT Depth vs. Window Size at 4 points along
profile (400x400m)
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2

3
4
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Cross-section derived from Seismic data

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Examples of manual MWT at well locations in
Middle East
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MWT example at well location 1

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Spectrum example at well location 1

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MWT example at well location 2

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Spectrum example at well location 2

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Conclusions

• The resolution of the survey data has significant
  impact on ability to accurately define depths
  using spectral analysis
• High resolution surveys with line spacings of 200
  and 400m are needed to image subtle
  intersedimentary horizons
• Widely spaced surveys of 1600 and 2000m are
  unlikely to resolve shallow features

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References

• Bankey, V., Grauch, V., J., S., Webbers, A., and
  PRJ, Inc. (2005). Open File Report 2005-1200,
  USGS
• Kivior, I., Boyd, D., Shi, Z. and McClay, K., R.,
  1993, Exploration Geophysics, 24, 603-608.
• Spector, A. and Grant, F., 1970, Geophysics, 35,
  293-302.
• Yates, S., Kivior, I., Damte, S., Markham, S., L.
  and Vaughan, F., 2008, in press.

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Acknowledgements
The data used for this study was made available
for research purposes by the USGS.
The data used for this study was made available
for research purposes by the USGS.