Delineation of near-surface paleochannel using shallow seismic reflection techniques
- and others
Shallow seismic reflection techniques were successful in delineating stratigraphic units and bedding geometries significant to the hydrologic modeling of unconsolidated sediments less than 60 in deep at Cherry Point Marine Air Base near Havelock, North Carolina. Discontinuous confining units beneath an industrialized portion of this major aircraft overhaul facility were thought to be due the erosion by a river that had cut through this area. Land shallow seismic reflection techniques provided images of alternating sand and clay sequences with average thicknesses on the order of 6 to 9 in. The land data have a dominant frequency of about 200 Hz, providing a minimum vertical bed resolution of about 2 in. Continuous seismic reflection data collected in the Neuse River directly north of the base have a dominant frequency around 600 Hz, providing a resolution potential of less than 1 in. Well defined cut and fill features that appear to have removed portions of the confining units are evident on the processed marine data. Correlation of the land CDP stacked seismic section with the drillhole-defined lithology was enhanced by incorporating electric logs and VSPs acquired in three strategically placed monitor wells. Some processed VSPs have interpretable reflections from within the upper 70 in that are consistent with the geologic section as inferred from drilling and electric logs. Subtle stratigraphic contacts, such as shell layers within sand or changes in the grain size of sand, were not easily interpretable on the CDP stacked sections. The land seismic reflection data provided the very high horizontal and vertical resolution necessary for determining continuity of confining units and stratigraphic variations between 10 and 60 in at this site.
- OSTI ID:
- 542867
- Report Number(s):
- CONF-951013-; TRN: 97:004463-0055
- Resource Relation:
- Conference: SEG `95: 65. annual meeting and international exposition of the Society of Exploration Geophysicists (SEG), Houston, TX (United States), 8-13 Oct 1995; Other Information: PBD: 1995; Related Information: Is Part Of SEG/Houston `95 - technical program; PB: 1623 p.
- Country of Publication:
- United States
- Language:
- English
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