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The AAPG/Datapages Combined Publications Database

Indonesian Petroleum Association


25th Annual Convention Proceedings (Volume 1), 1996
Pages 385-391

2-D and 3-D Prestack Depth Previous HitMigrationNext Hit for Complex Geologic Structures Offshore Indonesia

M. Murphy, R. Ottolini, R. Estill, E. Lumadyo, M. Mathias


Unocal Indonesia is using 3-D prestack depth Previous HitmigrationNext Hit to better image Indonesian prospects in difficult seismic areas. The goal is to delineate the deep fault geometry beneath image-distorting carbonates. Previous 2-D prestack depth Previous HitmigrationNext Hit has resulted in significantly better structural imaging, which is motivating the 3-D work.

Lateral velocity variations of 2 to 3 km/s within distances of less than 1 km make conventional time Previous HitmigrationNext Hit methods inadequate to accurately image structures and faulting. Iterative 2-D depth Previous HitmigrationNext Hit has provided better structural imaging in depth due to more accurate interval velocities and structural geometry resolution. 3-D prestack depth Previous HitmigrationNext Hit provides better Previous HitmigrationNext Hit velocity analyses and superior structural imaging, especially in comparison to 2-D lines acquired in directions oblique to major faults.

The most important step in depth Previous HitmigrationNext Hit is construction of a 3-D interval velocity model. All available data are used in constructing the model: Dip Moveout (Previous HitDMONext Hit) stacking velocities, poststack time Previous HitmigrationNext Hit, well logs, check-shot surveys, gravity and magnetic data, seismic interpretations, and the 3-D prestack depth Previous HitmigrationNext Hit velocity analyses. The model is developed iteratively from the surface downward. Modeling packages such as GOCAD assist the data integration and 3-D visualization quality control. The 3-D Previous HitmigrationNext Hit algorithm is a Unocal proprietary Kirchhoff Previous HitmigrationNext Hit with ray - trace traveltimes and Previous HitmigrationTop computed on a 3 Gigaflop, 10 CPU Silicon Graphics Power Challenge.

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