TEMPORAL AND SPATIAL SAMPLING CONSTRAINTS IN HIGH-RESOLUTION 3-D SEISMIC SURVEYS

An experimental, high-resolution 3-D seismic survey was acquired over a 1.5 km(2) section of an incised fluvial valley. The data were acquir ed as a near-zero offset, single-channel survey using a 15 in(3) water gun as the source, and differential GPS for navigation and positionin g. The objective was to acquire a 3-D seismic data Volume suitable for calculating the volume of shallow sand deposits. Horizontal time sect ions from the 3-D volume clearly show the flanks of the incised valley , as well as high-amplitude reflections interpreted as coarse-grained channel-lag deposits. The volume of this lag deposit can be calculated using the combination of the horizontal and vertical sections from th e high-resolution 3-D seismic data set. The results of the experiment also illustrate the importance of spatial sampling in 3-D seismic surv eying.