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New technique for acquisition of high-quality seismic data in Sacramento delta, California

Conference · · AAPG Bull.; (United States)
OSTI ID:6976966
The Sacramento delta is typified by relatively flat topography, numerous navigation channels, and extensive peat deposits. Seismic data acquired in the area have generally been poor, probably due to attenuation of seismic energy by the peat and to static problems caused by lateral velocity variations within the peat. In an attempt to obtain higher quality data, a test line was shot using a new field approach. The peat was penetrated using shothole drills and a seismic source and receiver assembly placed in each hole beneath the peat layer. The source consisted of dynamite and the receiver of a single low-cost disposable hydrophone. Thus, shooting and recording were conducted beneath the problematic peat layer. The line was acquired using an end-on spread, with energy being recorded at a given location until the location became a shotpoint of the hydrophone was destroyed. A geophone was planted at the surface at each location, thereby allowing a conventional line to be simultaneously recorded. Brute stacks show that high-quality data were recorded in the field using the downhole hydrophone technique. the surface geophone line, by contrast, was poor. Regional seismic lines were later acquired using these techniques, and they are of higher quality than lines previously recorded with surface phones. Seismic data acquired using the technique will allow mapping and direct hydrocarbon detection in presently nonproducing areas between Rio Vista and Roberts Island fields, California.
OSTI ID:
6976966
Report Number(s):
CONF-8804144-
Conference Information:
Journal Name: AAPG Bull.; (United States) Journal Volume: 72:3
Country of Publication:
United States
Language:
English