Onshore Croatia Reprocessing

Spectrum’s Egyptian joint-venture, Spectrum-Geopex have many years of experience in processing land seismic data. Their attention to detail and expertise enabled this successful seismic reprocessing project to be delivered to Spectrum’s Multi-Client department in time for the 1st Croatia Onshore Licensing Round.

The survey consists of over 11,500 km of mixed Vibroseis & dynamite data from over 22 different vintages, dating from the 1970’s through to the 1990’s.

Key challenges to this project:
• Building correct geometries from incomplete or erroneous observers reports
• Tying and matching all the different surveys
• Building a unified 3D static model
• Detailed noise suppression which was assessed on a line by line basis
• Horizon consistent velocity picking , using a smooth 3D field

Geological input and QC was supplied by Spectrum’s Geoscience group throughout the processing stages.

Animated Processing Sequence
Click on the image below to play the animated sequence…


Applied Processing Sequence
(highlighted steps correspond to image sequence above)

• Reformat, build geometry & load to database
• Seismic / Geometry merge
• Resample to 4ms sample rate
• De-spike / trace edit
• Spherical divergence compensation
• FK filter (shot domain)
• Surface Consistent Gain Correction
• Surface Consistent Deconvolution
• Refraction GLI Statics Statics applied to smooth near surface datum
• Velocity 1km
• Iterate x2
…o Residual Statics
…o Velocity 1km
• Radon demultiple
• Sort to common offset
• Pre Stack Time Migration
• Sort to CMP gathers
• Final Velocity
• Outer trace mute
• Statics applied to final 100m datum
• Apply 1000ms AGC
• Stack (fold 24)
• Q/Zero phase conversion
• Coherency enhancement
• Time variant filtering and scaling