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Application of blended sources offshore Abu DhabiNormal access

Authors: C.D.T. Walker, G. Ajlani, M. Hall, S. Al Masaabi, A. Al Kobaisi, G. Casson and H. Hagiwara
Journal name: First Break
Issue: Vol 35, No 11, November 2017 pp. 59 - 64
Language: English
Info: Article, PDF ( 1.09Mb )
Price: € 30

Summary:
Simultaneous or blended sources were initially developed for onshore applications using vibratory sources with dramatic improvements in both data quality and operational performance (Foster et al., 2010; Al-Ghamdi et al., 2010; Al-Mahrooqi et al., 2012). Offshore, there have been a number of both towed streamer and ocean bottom surveys acquired (Moore et al., 2012; Moldovaneau et al., 2013; Walker et al., 2013; Abma, 2014) where both data quality – through higher fold and improved survey efficiency – have again been amply demonstrated. The improvement in survey efficiency arising from simultaneous sources is clearly illustrated in Figure 1 (Etgen et al., 2015) where the combination of improved seabed receiver deployment rates and multiple simultaneous sources reduces the time needed to acquire a 400 km2 survey from 108 days to 21 days – a staggering 80% reduction in survey duration. There have been a number of approaches applied in these marine cases to ease the task of separating the desired shots from the unwanted ones – dithering the sources by small differences in firing time, distance separating the shooting vessels, firing each shot at pseudo-randomly distributed shot-point locations and operating the source vessels completely independently. In this article, we will focus on the application of the pseudo- random shot-point interval method offshore Abu Dhabi, where the very high amplitude levels of shot-generated low velocity Scholte wave noise (mud roll) represent a particular challenge given the long offsets cross-spread geometries needed to image the deep zone(s) of interest.


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