NAVIGATING
SEISMIC
CHALLENGES
T
he optimal velocity model that can
be expected from reflection seismic
data is one that generates flat gathers
following a prestack depth migration. In
some complex geological settings, the
seismic interpreter may observe questionable
structural geometries in the resulting stack.
These relate to the inaccuracy of the final
velocity model, despite the flatness of the
gathers. Ian Jones (2012) presents some
strategies to resolve different scenarios
for incorporating near-surface velocity
anomalies.
1
Some of the solutions are based
on moveout errors, which can be picked
along migrated gathers, while others are
based on observing the stacks and scanning
velocities by correcting unreliable geometries
along the depth stacks.
The proposed method is based on a
tomographic solution that does not use
reflection data, known as time preserving
tomography.
2
The objective is to update
the background velocity model from an
interpretation perspective. Any seismic
interpreter can apply this method in order
to adjust the background velocity model
and honour a plausible geological model.
Depth imaging experts may benefit from this
method, to explore and investigate the null
space while trying to resolve non-geological
features (e.g. false effects) derived from a
suspicious velocity model, while maintaining
the flatness of the migrated gathers.
Incorrectvelocitymodels
Depth imaging using incorrect velocity
models can easily lead to serious problems
in seismic data interpretation. Artifacts and
distorted depth images known as pull-ups
or pull-downs may be visible; their presence
BRUNO DE RIBET AND
GABY YELIN, PARADIGM,
USA, PRESENT A
TOMOGRAPHIC METHOD
FOR FACING CHALLENGES
IN THE INTERPRETATION
OF SEISMIC DATA.
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