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Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions John N. Louie, Presenter Tuning Phenomena.

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Presentation on theme: "Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions John N. Louie, Presenter Tuning Phenomena."— Presentation transcript:

1 Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions John N. Louie, Presenter Tuning Phenomena in Reservoirs Effect of Tuning on Stratigraphic Interpretation Deterministic Tuning Curves Statistical Tuning Curves Understanding the Magnitude of Tuning Effects John N. Louie, Presenter Tuning Phenomena in Reservoirs Effect of Tuning on Stratigraphic Interpretation Deterministic Tuning Curves Statistical Tuning Curves Understanding the Magnitude of Tuning Effects Geol 755: Basin Analysis Geophysics Week 6

2 Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions Effect of Tuning on Stratigraphic Interpretation When bed thickness, top and base reflections are separate. When bed thickness, top and base reflections are separate. When bed thickness <, reflections interfere and resonate- tuning When bed thickness <, reflections interfere and resonate- tuning

3 Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions Effect of Tuning on Stratigraphic Interpretation Where reflections merge, amplitude increases Where reflections merge, amplitude increases

4 Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions Effect of Tuning on Stratigraphic Interpretation In vertical and horizon section, amplitudes are highest where bed is thin- at the the tuning thickness. In vertical and horizon section, amplitudes are highest where bed is thin- at the the tuning thickness. Merged downdip reflections average the dip of the reservoir top & base. Merged downdip reflections average the dip of the reservoir top & base.

5 Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions Effect of Tuning on Stratigraphic Interpretation The limit of visibility depends on thickness as well as impedance contrast, and noise level The limit of visibility depends on thickness as well as impedance contrast, and noise level

6 Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions Deterministic Tuning Curves Have to differentiate tuning effects from variations in properties (like porosity and fluid content) Have to differentiate tuning effects from variations in properties (like porosity and fluid content) Tuning is a purely geometric effect Tuning is a purely geometric effect The ideal tuning thickness is /4 The ideal tuning thickness is /4

7 Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions Deterministic Tuning Curves Sidelobes of wavelets also tune for thicker intervals Sidelobes of wavelets also tune for thicker intervals

8 Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions Deterministic Tuning Curves Different wavelets will tune to different degrees Different wavelets will tune to different degrees May be multiple maxima on the tuning curve May be multiple maxima on the tuning curve

9 Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions Statistical Tuning Curves Can cross-plot amplitudes from related locations to examine correlations Can cross-plot amplitudes from related locations to examine correlations Linearity here suggests changes within reservoir, not outside Linearity here suggests changes within reservoir, not outside

10 Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions Statistical Tuning Curves Reflection amplitude against interpreted thickness Reflection amplitude against interpreted thickness

11 Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions Statistical Tuning Curves Reflection amplitude against interpreted thickness Reflection amplitude against interpreted thickness The envelope is a statistical tuning curve The envelope is a statistical tuning curve

12 Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions Statistical Tuning Curves Reflection amplitude against interpreted thickness Reflection amplitude against interpreted thickness The envelope here follows a percentile of amplitudes The envelope here follows a percentile of amplitudes

13 Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions Statistical Tuning Curves Reflection amplitude against interpreted thickness Reflection amplitude against interpreted thickness The envelope here is compared with a deter- ministic curve The envelope here is compared with a deter- ministic curve

14 Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions Understanding the Magnitude of Tuning Effects Wavelet shape is critical to knowing where tuning is occurring. Wavelet shape is critical to knowing where tuning is occurring.

15 Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions Understanding the Magnitude of Tuning Effects Wavelet shape is critical to knowing where tuning is occurring. Wavelet shape is critical to knowing where tuning is occurring.

16 Taken From: Alistair R. Brown, AAPG Memoir 42, Interpretation of Three- Dimensional Seismic Data, 4th & 6th Editions Understanding the Magnitude of Tuning Effects The first side lobe as a fraction of the center lobe of a zero-phase wavelet is the reciprocal of the octave bandwidth.The first side lobe as a fraction of the center lobe of a zero-phase wavelet is the reciprocal of the octave bandwidth. Good seismic data has 2.5 octaves, for a side lobe level of 40% relative to the center. Good seismic data has 2.5 octaves, for a side lobe level of 40% relative to the center. This 40% rule means that 40% is a common increase in amplitude at tuning for zero phase wavelets, reflected from the top and base of a reservoir layer. This 40% rule means that 40% is a common increase in amplitude at tuning for zero phase wavelets, reflected from the top and base of a reservoir layer. Greater increases in amplitude must be explained otherwise. Greater increases in amplitude must be explained otherwise.


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