pitfalls in seismic interpretation - west virginia...

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Tom Wilson, Department of Geology and Geography

Environmental and Exploration Geophysics II

tom.h.wilsontom.wilson@mail.wvu.edu

Department of Geology and GeographyWest Virginia University

Morgantown, WV

Pitfalls in Seismic InterpretationPitfalls in Seismic Interpretation

Tom Wilson, Department of Geology and Geography

• Exercise IV-VI will be due this Wednesday.

Any Questions ….

• Problems 4.4 and 4.8 are due today.

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Tom Wilson, Department of Geology and Geography

Geometrical and Velocity Pitfalls

Tucker and Yorston

Tom Wilson, Department of Geology and Geography Tucker and Yorston

Velocity pitfalls

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Tom Wilson, Department of Geology and Geography

Tucker and Yorston

Tom Wilson, Department of Geology and GeographyTucker and Yorston

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Tom Wilson, Department of Geology and GeographyTucker and Yorston

Tom Wilson, Department of Geology and Geography Tucker and Yorston

Disconformities and superimposed dip sets

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Tom Wilson, Department of Geology and Geography Tucker and Yorston

Diffraction apex marks the spot.

Tom Wilson, Department of Geology and Geography Tucker and Yorston

“Static” anomalies

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Tom Wilson, Department of Geology and Geography Tucker and Yorston

Tom Wilson, Department of Geology and Geography

Flat Reflector

Apparent structural features are related to variations in thickness of near-surface low-velocity weathered layer.

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Tom Wilson, Department of Geology and Geography

Apparent low in the time structure

Tom Wilson, Department of Geology and Geography

Low to southwest also observed in pre-stack depth converted seismic

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Tom Wilson, Department of Geology and Geography

Note that the lows tend to be concentrated in the valleys

Tom Wilson, Department of Geology and Geography

We actually have a structural high in this area

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Tom Wilson, Department of Geology and Geography

Note that the lows tend to be concentrated in the valleys

Tom Wilson, Department of Geology and Geography Tucker and Yorston

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Tom Wilson, Department of Geology and GeographyTucker and Yorston

Velocities increase with burial depth

Tom Wilson, Department of Geology and Geography

Interval velocities

1500 1900 2300 2700 3100 3500 3900 4300 4700 5100 5500 5900

Trav

el ti

me

0

250500

7501000

12501500

17502000

22502500

27503000

32503500

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Tom Wilson, Department of Geology and Geography

Average Velocity (north sea)

1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 2500 2600 2700 2800Ti

me

0

250500

7501000

12501500

17502000

22502500

27503000

32503500

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Tom Wilson, Department of Geology and Geography Tucker and Yorston

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Tom Wilson, Department of Geology and GeographyTucker and Yorston

Tom Wilson, Department of Geology and GeographyTucker and Yorston

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Tom Wilson, Department of Geology and Geography

Velocity usually increases with Depth

Tom Wilson, Department of Geology and GeographyTucker and Yorston

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Tom Wilson, Department of Geology and GeographyTucker and Yorston

Increased thickness of the high velocity carbonate

Tom Wilson, Department of Geology and GeographyTucker and Yorston

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Tom Wilson, Department of Geology and Geography

Tucker and Yorston

Tom Wilson, Department of Geology and Geography

Tucker and Yorston

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Tom Wilson, Department of Geology and Geography

Tom Wilson, Department of Geology and Geography

Tucker and Yorston

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Tom Wilson, Department of Geology and Geography

Tucker and Yorston

Tom Wilson, Department of Geology and Geography

Tucker and Yorston

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Tom Wilson, Department of Geology and Geography

Tucker and Yorston

Tom Wilson, Department of Geology and Geography

Tucker and Yorston

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Tom Wilson, Department of Geology and Geography

Tucker and Yorston

Tom Wilson, Department of Geology and Geography

Toelle et al, 2007

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Tom Wilson, Department of Geology and Geography

Faults or velocity?

Tom Wilson, Department of Geology and Geography

ErosionalTruncation?

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Tom Wilson, Department of Geology and Geography

Tucker and Yorston

Tom Wilson, Department of Geology and Geography Tucker and Yorston

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Tom Wilson, Department of Geology and Geography

Tucker and Yorston

Tom Wilson, Department of Geology and Geography

Tucker and Yorston

The velocity sag

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Tom Wilson, Department of Geology and Geography

Velocity sag over central diapir?

Velocity sag?

Tom Wilson, Department of Geology and Geography

Tucker and Yorston

The velocity pull-up

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Tom Wilson, Department of Geology and Geography

Structural high/fault or velocity pullup? Central Diapir

Tom Wilson, Department of Geology and Geography

<Western diapir

Western diapir

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Tom Wilson, Department of Geology and Geography

Tom Wilson, Department of Geology and Geography

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Tom Wilson, Department of Geology and Geography

Tom Wilson, Department of Geology and Geography

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Tom Wilson, Department of Geology and Geography

• Exercise V-VI will be due this Wednesday. We’ll discuss problem VI today.

• Problems 4.4 and 4.8 are due today.

Tom Wilson, Department of Geology and Geography

• Read through pages 229 to 232 (static corrections) and look over problem 4.14

• Look over the velocity analysis pitfalls exercise handed out today

Bring questions to class on Monday