Imaging under the edges of salt bodies: Analysis of an Elf North Sea dataset

Marie L. Prucha, Robert G. Clapp, and Biondo L. Biondi

marie@sep.Stanford.EDU, bob@sep.Stanford.EDU, biondo@sep.Stanford.EDU

ABSTRACT

Depth imaging techniques still face difficulties under the edges of salt bodies. Elf encountered such a problem in a 3-D survey in the North Sea where they hoped to image a reflector that lays beneath a salt body. Based on the 3-D data, Elf created 2-D synthetic model of the salt body and surrounding subsurface. By analyzing this synthetic model using Kirchoff depth migration and raytracing techniques, it became clear that the problem is largely due to poor illumination. The portion of the reflector under the edge of the salt dome only received illumination from a limited range of offsets. In addition to further analysis of both the synthetic and real datasets, investigations of possible solutions such as weighting appropriate offsets, inversion and/or the use of common reflection angle gathers seem warranted.