Shear-wave studies of the near-surface at the CaMI Field Research Station in Newell County, Alberta

Don C. Lawton, J. Helen Isaac and Malcolm Bertram

ABSTRACT

Two S-wave seismic surveys were acquired at the CaMI Field Research Station (FRS) in the summer of 2018 using Echo Seismic Ltd’s S-wave Envirovibe. For the first survey receivers were placed every 10 m in a fixed array and the source interval was 20 m. The second survey consisted of a 72-m streamer array towed behind the truck. The source interval was 2 m and the receiver interval was 1 m. The recorded S-wave data are of good quality with clear first breaks. A smoothed S-wave velocity model was derived from refraction statics analysis. The near-surface S-wave low velocity layer is 28.5 to 34.5 m thick, with velocities ranging from 222 to 280 m/s. The S-wave bedrock velocity ranges between 1045 and 1110 m/s. The depths to bedrock compare well with the actual bedrock depth of 29.5 m at the injection well location. We applied some basic processing to both surveys, stacked and migrated them. The streamer array line images the bedrock very well. This line was converted to depth using the refraction velocities. The depth of imaged bedrock compares very well with the true bedrock depth of 29.5 m at the injection well.

Application of the receiver statics derived from the fixed array survey to the PS data acquired in 2017 improved the imaging of the Basal Belly River reflector on stacked sections.

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