Description of the available data

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.

• Acquisition area 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.
   

  Acquisition_parameters Figure 9 2001 survey acquisition geometry.

  

• 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.