In:
GEOPHYSICS, Society of Exploration Geophysicists, Vol. 77, No. 2 ( 2012-03), p. B87-B96
Abstract:
Depth imaging in ultrashallow ([Formula: see text]) environments presents twofold challenge: (1) c oda available for depth migration is very limited; and (2) conventional time processing with limited coda generally fails to estimate reliable velocity models for depth migration. We studied the combining of first-arrival traveltime inversion and prestack depth migration (PSDM) for depth imaging of ultrashallow paleochannel stratigraphy associated with the Bull Creek drainage system, Oklahoma. Restricted by a limited number of geophones (24) we acquired data for inversion and migration through two coincident profiles. The first profile for inversion has a wider survey-aperture (115-m maximum shot-receiver spacing) and consequently sparse CMP spacing (2.5 m), whereas the second profile for PSDM has denser CMP spacing (1 m) and consequently a narrower survey aperture (46-m maximum shot-receiver spacing). We also found that the velocity model from traveltime inversion of the wider-aperture data set is more preferable for depth-migration than the velocity model from time processing of the denser data set. The preferred depth image showed three episodes of incision whose chronological order is resolved through radio-carbon dating of terrace sediments. Results suggested that even with limited geophones, depth imaging of ultrashallow targets can be achieved by combining first-arrival traveltime inversion and PSDM through coincident wide- and narrow-aperture acquisitions.
Type of Medium:
Online Resource
ISSN:
0016-8033
,
1942-2156
DOI:
10.1190/geo2011-0218.1
Language:
English
Publisher:
Society of Exploration Geophysicists
Publication Date:
2012
detail.hit.zdb_id:
2033021-2
detail.hit.zdb_id:
2184-2
SSG:
16,13
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