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7th Middle East Geosciences Conference and Exhibition
Manama, Bahrain
March 27-29, 2006
Migration
of a Land Survey with Considerable Multiple Interference - A Case
History
1 Exploration Technical Services Department, Saudi Aramco, P.O. Box 12473, Dhahran, 31311, Saudi
Arabia, phone: 96638733665, [email protected]
2 Exploration Technical Services Department, Saudi Aramco, P.O. Box 12887, Dhahran, 31311, Saudi Arabia
3 Exploration Operations Dept./Geophysical Data Processing Div, Saudi Aramco, PO Box 11443, Dhahran, 31311, Saudi Arabia
Saudi Aramco has started the application of 3D pre-stack depth migration
to improve seismic imaging of deep targets.
Historically, processing which included dip move out and post-stack depth
migration
effectively imaged most of the shallow
exploration and development targets. Recently, some of the deeper, faulted targets required the use of 3D pre -stack depth
migration
(Pre-SDM). Applying 3D Pre-SDM on high fold seismic surveys', reaching up to 960 fold, presents a unique
challenge. Such large data sets have tested the limits of software and computer resources.
Much effort was focused on the initial velocity model development. Several models were created using check shots, sonic
logs, pre-stack time migration
root mean square velocities and pseudo apparent interval velocities. Velocity model updating
was also challenging due to multiple energy contamination. An innovative approach was internally developed to attenuate
multiples on high fold common mid-point gathers. The application of this method on common image gathers proved to be
effective in improving the velocity model updating procedure.
The pre-stack depth migrated results show better imaging of the primary reflections leading to better fault definition and positioning. These imaging improvements have allowed more effective placement of exploration, delineation and development wells.