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7th Middle East Geosciences Conference and Exhibition
Manama, Bahrain
March 27-29, 2006
AVO
Analysis Based on the CRS Method
1 TEEC, Burgwedelerstr. 89, Isernhagen HB, 30916, Germany, phone: +49 511 7240452, fax: +49 511
7240465, [email protected]
2 TEEC, Burgwedeler Str. 89, Isernhagen, D-30916, Germany
The Common-Reflection-Surface (CRS) method which was developed in recent years, has increasingly been used for the
high resolution imaging of complex subsurface structures. Assuming subsurface reflector elements with dip and curvature,
the CRS method renders a better signal-to-noise ratio and additional subsurface information in comparison to conventional
NMO/DMO time domain imaging. These advantages of the CRS method, however, may as well be used for an improved
Amplitude Versus Offset (AVO
) analysis. A conceptual case study shows that the more realistic subsurface assumptions,
and the increased fold of the CRS imaging, allow to extend
AVO
analysis into noise zones. The signal-to-noise ratio of the
CRS
AVO
gradient stack is much higher than in conventional
AVO
. Extreme fluctuation of
AVO
parameters is removed, and
AVO
anomalies are enhanced. In the case study, the CRS
AVO
gradient stack clearly distinguishes an anomaly at a known
gas bearing reservoir. Small anomalies above the reservoir disappear, indicating that they were due to local noise
contamination. Cross plots of the
AVO
intercept versus gradient show a better separation of anomalous zones which may
be classified in order to identify top and base of hydrocarbon deposits. Based on the local CRS imaging solution, the
general increase of the signal-to-noise ratio imply an improved
AVO
analysis by CRS for many types of data. Large benefits
of CRS
AVO
is especially expected in areas of strong dip, and at deep targets with a low signal-to-noise ratio.