Three-component seismic data processing: Carrot Creek, Alberta
Mark Paul Harrison
A survey using three-component geophones to record seismic reflection data from a vibrator source was conducted in the Carrot Creek area of Alberta. Two lines were recorded in total, each having components in the vertical, radial, and transverse directions.
This report outlines the data-processing sequence that is currently being used for converted-wave analysis using the CREWES data processing centre. In particular, results are shown for the vertical (P-wave) and radial (SV-wave) components of line CC-SW-01 of the Carrot Creek survey.
Little reflection signal was seen on the transverse component records. This suggests that any velocity anisotropy in the area is either small enough to neglect, or the line orientation relative to the direction of anisotropy gives negligible rotation of SV shear energy propagating in the line plane.
It was found in processing the radial-component data that the source static solution obtained from the vertical component processing was appropriate for the converted shear data. The vertical component receiver statics, however, were not able to properly correct the radial component receivers. From common-receiver surface stacks, short wavelength residual statics as high as 60 ms were seen to remain in the radial component data. There appears to be little correlation between the size and location of static pockets found on the radial component data to those found on the vertical component data.
Processing of the radial component data set resulted in a stacked section for the converted-wave shear energy. Enough signal strength exists to allow the correlation of events between the P-P and P-SV sections, allowing the rough computation of average Vp/Vs ratios between events.
The target in this area is the oil-bearing Cardium formation, which is a thin Upper Cretaceous sandstone and conglomerate. A pronounced brightening is seen to occur on the SV-wave section at two locations on the line, both of which correspond to known pools. Little amplitude change is visible on the P-wave section at these locations.