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1
A new method to calculate
pore pressure
from stacked seismic data
QProtected by US Patent No. 6,681,185
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2
Q stands for Quality Factor
Q is the inverse of attenuation
Q-Based Pore Pressure
What is Q?
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3
Numerous authors have reported on the experimental
relationship between Qp and Pressure (Peff stress ,Pp) .
Birch and Bancroft
Johnston et al
Lucet and Zinszner
Best and Sams
Carcione
Siggins and Dewhurst
Experimental Results
Such as:
With results like this
1938
1979
1992
1997
2000
2001
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4
Lab Results
OTC 13043
Stress Path, Pore Pressure and Microstructural Influences on Q in Carnarvon
Basin Sandstones
A.F. Siggins and D.N. Dewhurst (CSIRO Petroleum, Australia) and P.R. Tingate (National
Centre for Petroleum Geology and Geophysics, University of Adelaide, Australia).
5% Change 150% Change
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5
An Intuitive Explanation
Q-Based Pore Pressure
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6
Q-Based Shale Pore Pressure
Hi Q
Frequency
Low Q
Frequency
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7
Q Responds to Effective Stress
Normal Pressure
Over PressureEffective
stress
Pore
Pressure
Frequency
Hi Q
Frequency
Frequency
Low Q
Frequency
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8
Procedure
Q-Based Pore Pressure
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9
Q-Based PP Procedure
Frequency
Decay Pore Pressure
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10
Deep Water Frequency Trend
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PP-V Calibration
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PP-Q Calibration
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13
Q-Based Shale PP
Calibrated PP from seismic frequencies
Well B Well A
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14
Why Use Two Methods to
Calculate PP?
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15
Q-Based Shale PP
Calibrated PP from seismic frequencies
Well B Well A
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16
V-Based Shale PP
Calibrated PP from seismic velocities
Well B Well A
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17
Velocity Responds to LithologyD
epth
DT
Sand Trend
Shale Trend
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18
Examples
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19
Water Bottom
Shale
Moderate
Sand/Shale
Ratio
Steep Structure
Causing
Seismic Velocity Issues
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20
Water Bottom
PP-Q
PP-V
Sandy and Tight
Shaley
Clastics
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21
PP-V PP-Q
Shale
Sandy
Shale
Carbonate
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22
PP-Q
PP-V
LIFGNow including a lithology influenced frac-gradient, LIFG.
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23
Using Multiple Pore Pressure Prediction
Techniques provides a way to mitigate
risk.
Conclusion
Recommended