Challenges on Ultra High-Density Seismic Survey - Array Free Processing

In early 2011, the acquisition of an Ultra-High-Density Wide Azimuth seismic dataset was successfully done. The acquisition design consisted of orthogonal cross-spreads with very dense single source - single receiver (7.5 m interval). The objective for this 3D survey was to improve data quality and resolution on small faults, fracture zones and structural imaging of shallow and deeper reservoirs. Such dense sampling was designed to record the de-aliased signal and noise for highly effective noise suppression, whilst ensuring the integrity of the broadband signal. Two routes were chosen for the processing: the first one was to reduce the data volume via a Digital Array Forming and then follow a conventional processing sequence with a bin size of 15 m x 15 m; the second was to process the Array Free data as such (all acquired traces) keeping the original bin size of 3.75 m x 3.75 m. The Array Free processing reveals in turn all the benefits of Array Free acquisition. Our experience shows that this solution gives us the best possible signal preservation over the entire seismic bandwidth.