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AAPG Bulletin, Vol. 90 (2006), Program Abstracts (Digital)

7th Middle East Geosciences Conference and Exhibition
Manama, Bahrain
March 27-29, 2006

EXTENDED ABSTRACT: Resolution of Static Previous HitCorrectionsNext Hit in Sand Dune Regions: A Successful Case History

Koshy Thayyil, Djafar Aitsaadi, Mohammad Al-Homaili and Ralph Bridle
Saudi Aramco

In areas prevalent with sand dunes, conventional assumptions for datum static correction computation can become invalid. The Rub Al-Khali region is well known for sand dunes and sabkha (salt mudflats). Variations in elevation and travel time from dune base to crest are too much for routine static correction methods. This case history shows a successful strategy of solving particular components of the static Previous HitcorrectionsNext Hit independently before combining them. The components include: the sand dune correction, the base of sand to datum correction, the Previous HitrefractionNext Hit and reflection residual static correction.

A regionally defined time/depth curve describing dune compaction in this area yields sand dune travel times. Final datum Previous HitstaticsNext Hit are calculated by adding this time to the time from base of sand to final datum, using a velocity model derived from upholes.

High and low frequency components within the composite datum Previous HitstaticsNext Hit Previous HitcorrectionsNext Hit are separated. A fter applying only the high frequency Previous HitstaticsNext Hit, the seismic data is corrected to a smooth floating datum. To prevent stacking velocity distortions datum Previous HitstaticsNext Hit are applied from base of sand to final datum with the sand time applied residually.

U nc orrec ted time shifts remain in this initial model, due to differential slip and dip face compaction, and other anomalous surface consistent effects. Surface consistent Previous HitrefractionNext Hit residual Previous HitstaticsNext Hit are computed and applied on linear moveout corrected data. The static Previous HitcorrectionsNext Hit are completed with surface consistent reflection residual Previous HitstaticsNext Hit.

This method led to a focused time section.

Figure 1. Before Application of Previous HitCorrectionsNext Hit.

Figure 2. After Application of Previous HitCorrectionsTop.

 

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