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7th Middle East Geosciences Conference and Exhibition
Manama, Bahrain
March 27-29, 2006
Velocity
 
Analysis
: Focusing 3-D 
data
 from Offshore Abu Dhabi
1 AGRI, KACST, PO Box 6086, Riyadh, 11442, Saudi Arabia, phone:
+966-1-4813323, fax: +966-1-4813523, [email protected]
2ADMA-OPCO, PO BOX 303, Abu Dhabi, United Arab Emirates
The 3-D 
data
 set from offshore Abu Dhabi has suffered from shallow 
velocity
 anomalies concentrated in center of the
surveyed region and above the critical reservoirs area. Previous processing results, that mainly ignored such anomalies,
produced images that lacked reflection signatures in that middle critical region. Even those processing methods that have
tried to predict the anomaly, but are based on prestack depth migration concept, have failed to focus the image at the
center. Thus, we use the inherent stability features of representing the image and all processes prior in the TAU instead of
the depth domain to estimate the interval 
velocity
 model for this 3-D 
data
 set. The process is based on prestack 3-D
migration 
velocity
 
analysis
 and thus honors the complex inhomogeniety up shallow in that region. The final estimated
interval 
velocity
 model in the TAU domain provided low residuals in the imaged sections from different offsets and agreed
well with the four wells located in the area. This 
velocity
 model also encompassed all the main features of the region like the
low 
velocity
 zone up shallow and the major fault present in the middle of the region. Using the 
velocity
 model we applied 3 -
D prestack TAU migration to the full 
data
 as opposed to subsets of the 
data
 as done in the 
velocity
 development stage. As a
result of using the TAU domain, we managed focus the image far better than in previous attempts. Using the new images,
we managed to identify the location of the major sealing fault, and recognize major structures in the central zone.