Print Email Facebook Twitter Converted waves in a shallow marine environment: Experimental and modeling studies Title Converted waves in a shallow marine environment: Experimental and modeling studies Author El Allouche, N. Drijkoningen, G.G. Versteeg, W. Ghose, R. Faculty Civil Engineering and Geosciences Department Geoscience & Engineering Date 2011-01-05 Abstract Seismic waves converted from compressional to shear mode in the shallow subsurface can be useful not only for obtaining shear-wave velocity information but also for improved processing of deeper reflection data. These waves generated at deep seas have been used successfully in hydrocarbon exploration; however, acquisition of good-quality converted-wave data in shallow marine environments remains challenging. We have looked into this problem through field experiments and synthetic modeling. A high-resolution seismic survey was conducted in a shallow-water canal using different types of seismic sources; data were recorded with a four-component water-bottom cable. Observed events in the field data were validated through modeling studies. Compressional waves converted to shear waves at the water bot-tom and at shallow reflectors were identified. The shear waves showed distinct linear polarization in the horizontal plane and low velocities in the marine sediments. Modeling results indicated the presence of a nongeometric shear-wave arrival excited only when the dominant wavelength exceeded the height of the source with respect to the water/sediment interface, as observed in air-gun data. This type of shear wave has a traveltime that corresponds to the raypath originating not at the source but at the interface directly below the source. Thus, these shear waves, excited by the source/water-bottom coupled system, kinematically behave as if they were generated by an S-wave source placed at the water bottom. In a shallow-water environment, the condition appears to be favorable for exciting such shear waves with nongeometric arrivals. These waves can provide useful information of shear-wave velocity in the sediments. Subject data acquisitiongeophysical prospectinghydrocarbon reservoirssedimentsseismic wavesseismology To reference this document use: http://resolver.tudelft.nl/uuid:fd60045d-ed3b-487f-a251-085255996931 DOI https://doi.org/10.1190/1.3511524 Publisher Society of Exploration Geophysicists ISSN 0016-8033 Source Geophysics, 76 (1), 2011 Part of collection Institutional Repository Document type journal article Rights (c) 2011 Society of Exploration Geophysicists Files PDF ElAllouche_2011.pdf 49.21 MB Close viewer /islandora/object/uuid:fd60045d-ed3b-487f-a251-085255996931/datastream/OBJ/view