Wide Azimuth Simultaneous Acquisition Marine Experiment; A Synthetic Study
Tsingas, Constantine *1; Huo, Shoudong 1; Lorentz, Gary 1; Wang, MingXing 2; Jervis, Michael 1; Musser, James A.1; Kelamis, Panos 1
(1) Saudi Aramco, Dhahran, Saudi Arabia. (2) SINOPEC, Dhahran, Saudi Arabia.
Marine blended source acquisition is increasingly gaining ground in the seismic industry due to the possibility of reducing costs and improving field acquisition efficiency. However, one major drawback of marine blended acquisition is the crosstalk noise generated by the nearly simultaneous firing of the airgun arrays. It is essential to understand the characteristics of this noise and identify proper acquisition techniques and processing workflows to reduce its effects on image quality.
We start by 3D finite difference modeling of a complex subsurface and then we combine the synthetic shots to simulate a four boat wide azimuth (WAZ) acquisition marine survey comprised of two streamer vessels with sources, and two additional source vessels between the streamer spreads and off the tails of the streamers. Each source fires nearly simultaneously with a randomized time lag of up to 500 milliseconds between sources. Overall, the gain from using this simultaneously firing marine acquisition design versus a conventional four-vessel WAZ marine design is about a 2.67 times increase in terms of both source density and achieved fold, and it can be acquired in about the same amount of acquisition time as compared to the conventional four vessel WAZ survey. In general, most of the processing techniques for the simultaneous source blended data rely on the fact that crosstalk noise exhibits coherency in the shot domain but appears random when viewed in a different data domain, such as in the common depth point (CDP) domain.
A number of processing techniques are applied in several data domains and their effectiveness is evaluated and compared to processing the original non-blended synthetic data. Direct comparisons between the processed blended source and conventional WAZ data reveal significant uplift in the seismic image due to the increased shot density and fold.
AAPG Search and Discovery Article #90141©2012, GEO-2012, 10th Middle East Geosciences Conference and Exhibition, 4-7 March 2012, Manama, Bahrain