Velocity/interface model building in a thrust belt by tomographic
inversion of global offset seismic data
Geophysical Prospecting, 51 (1):
23--35 (January 2003)DOI: 10.1046/j.1365-2478.2003.00351.x
Abstract
Between September and November 1999, two test seismic lines were recorded
in the southern Apennine region of southern Italy using the global
offset technique, which involves the acquisition of a wide offset
range using two simultaneously active seismic spreads. One consisted
of a symmetrical spread moving along the line, with geophone arrays
every 30 m and a maximum offset of 3.6 km. The other one consisted
of fixed geophone arrays every 90 m with a maximum offset of 18 km.
This experimental acquisition project was carried out as part of
the enhanced seismic in thrust belt (ESIT) research project, funded
by the European Union, Enterprise Oil and Eni-Agip. An iterative
and interactive tomographic inversion of refraction/reflection arrivals
was carried out on the data from line ESIT700 to produce a velocity/interface
model in depth, which used all the available offsets. The tomographic
models allowed the reconstruction of layer interface geometries and
interval velocities for the target carbonate platform (Apula) and
the overburden sequence. The value of this technique is highlighted
by the fact that the standard approach, based on near-vertical reflection
seismic and a conventional processing flow, produced poor seismic
images in both stack and migrated sections.