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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

ABSTRACT: Subsalt Imaging: Beyond Depth Previous HitMigrationNext Hit and Model Building

Biondo Biondi
Geophysics Department - Stanford Exploration Project, Stanford University, Mitchell Bldg, 397 Panama Mall, Stanford, CA 94305-2215, phone: (650)723-1319, [email protected]

Large hydrocarbon reservoirs are located below salt bodies in several areas of the world, such as the Gulf of Mexico, the Persian Gulf, and offshore West Africa. In these areas, economical recovery of the hydrocarbons depends on our ability to image the reservoir with seismic data. Seismic imaging below salt bodies is a challenging task that pushes the limits of current imaging methods. The difficulties are associated with the complexity of the wave -propagation phenomena that occur when the seismic wavefield interacts with the salt body (e.g. multi -pathing, scattering, mode conversion) and with the structural complexity of the salt bodies and the target reservoirs.

The routine use of Previous Hit3-DNext Hit Previous HitprestackNext Hit depth Previous HitmigrationNext Hit, and in particular of wave-equation Previous HitmigrationNext Hit, had a positive impact on many exploration projects. However, simple Previous HitmigrationNext Hit has difficulties to produce artifact-free images where the salt geometry prevents an even illumination of the subsalt reflectors from surface data.

A promising research direction is to go beyond simple wave-equation Previous HitmigrationNext Hit and instead iteratively invert Previous Hit3-DNext Hit waveequation operators. I will illustrate this idea by describing two research projects. The first project aims at improving the image of poorly illuminated areas by inverting a Previous Hit3-DNext Hit one-way wavefield operator. The second project developed a robust Previous HitMigrationTop Velocity Analysis (MVA) method based on wave-equation operator, that can be used where conventional raybased tomography fails. This method bypasses the difficulties involved in tracing high-frequency rays through a complex salt body and accurately models finite-frequency wave propagation.

 

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