Abstract
To obtain high-resolution of the subsurface structure, we modeled multi-depth slanted airgun sources to attenuate the source ghost. By firing the guns in sequence according to their relative depths, such a source can build constructive primaries and destructive ghosts. To evaluate the attenuation of ghosts, the normalized squared error of the spectrum of the actual vs the expected signature is computed. We used a typical 680 cu.in airgun string and found via simulations that a depth interval of 1 or 1.5 m between airguns is optimum when considering deghosting performance and operational feasibility. When more subarrays are combined, preliminary simulations are necessary to determine the optimum depth combination. The frequency notches introduced by the excess use of subarrays may negatively affect the deghosting performance. Two or three slanted subarrays can be combined to remove the ghost effect. The sequence combination may partly affect deghosting but this can be eliminated by matched filtering. Directivity comparison shows that a multi-depth slanted source can significantly attenuate the notches and widen the energy transmission stability area.
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This research is financially supported by the national 863 program (2013AA064202) and Marine subject interdisciplinary and guidance fund of Zhejiang University (188040+193414Y01).
Shen Hong-Lei: See biography and photo in the Applied Geophysics January 2013 issue, P. 24.
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Shen, HL., Elboth, T., Tian, G. et al. Modeling of multi-depth slanted airgun source for deghosting. Appl. Geophys. 11, 405–417 (2014). https://doi.org/10.1007/s11770-014-0461-1
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DOI: https://doi.org/10.1007/s11770-014-0461-1