TOTAL UK provided us with the data from the
2001 acquisition (preprocessed recently by Veritas), the
isotropic interval velocity model developed by CGG in 2003, and
the data from 15 nearby wells.
In 2001, approximately 260 km2 of 3D seismic full-fold data
was acquired with an interleaved acquisition. The available seismic
data spans 180 km2.
2001 survey acquisition parameters
The main parameters of the acquisition are illustrated in
Figure . The shotpoint interval is
18.75 meters. The bin size of the data preprocessed by Veritas in 2006
is 6.25 meters by 18.75 meters, corresponding to a stacking fold of 108.
Isotropic Velocity model
We were provided with the final isotropic interval velocity depth
model computed by CGG. The blocky velocity model was first built in
time using the interpreted time-horizons, the surface seismic stacking
velocities and the compaction gradients given by the wells. It was
then updated by layer-stripping. Two different updating
methods were used. The first one was to compute CRP scans and
perform normal-ray update. The second method was to pick residual
curvature and perform multi-offset velocity
updates. Figure illustrates the
final isotropic velocity model for Line 750.