Print this pageAbstract: Precaspian Basin:
Vanishing 
Salt
KLARNER, SABINE, MATTHIAS KOERBE, and PAUL KRAJEWSKI
Traditionally zones
of non- or poor reflectivity in seismic sections have been used to document
the presence of massive Permian age salt diapirs in the eastern part of
the Precaspian Basin.
Experience from the salt bearing
Northern German Basin gained during the last decade offers an alternative
model for the Precaspian Basin. In Northern Germany, the apparent volume
of salt in the seismic section decreases proportionally to the improvement
of processing techniques applied.
Reprocessing of preexisting
Kazakh data using these processing experiences resulted in considerable
improvement in the coherency of the seismic events. The enhanced seismic
resolution yields a new interpretation for the salt flanks and salt overhangs.
The optimized processing sequence includes but is not restricted to surface
consistent deconvolution, use of dip moveout, detailed velocity analysis,
steep dip migration and preservation of amplitude characteristics. Prestack
depth migration of representative seismic sections has led to better definitions
of the amount and shape of the salt.
Interpretation of reprocessed
Kazakhian seismic data as well as new data acquired by Preussag Energie
provides very little evidence for large salt bodies. Instead the seismic
data support a model consisting of a certain number of large salt overhangs
with narrow roots. In many cases towards the basin center the salt stem
has vanished. It is replaced by secondary welds between rim syncline complexes.
Several of the overhangs are connected by "salt bridges". The "salt bridges"
represent the remnants of the former pierced salt
walls.
AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria