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 km2 section of an incised fluvial valley. The data were acquired as a near-zero offset, single-channel survey using a 15 in3 water gun as the source, and differential GPS for navigation and positioning. The objective was to acquire a 3-D seismic data volume suitable for calculating the volume of shallow sand deposits. Horizontal time sections 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 the high-resolution 3-D seismic data set. The results of the experiment also illustrate the importance of spatial sampling in 3-D seismic surveying.