3C-3D VSP: The Blackfoot experiment

Jitendra S. Gulati, Robert R. Stewart, and John M. Parkin

ABSTRACT

A 3C-3D VSP was acquired over the Blackfoot oil field in Alberta, Canada in 1995. The 3-D VSP was recorded simultaneously with a surface 3C-3D seismic program. The objectives of the 3-D VSP were to define recording logistics, develop data handling and processing procedures, and determine if the 3-D VSP could image the reservoir.

The shots in the surface 3C-3D seismic survey that fell within 2200m offset from the recording well were used in the 3-D VSP. As the shots for the surface 3-D were being taken, the borehole tool moved seven times (75m each) recording over a receiver depth range from 400m to 910m. The 3-D VSP data were processed using basic VSP processing techniques that involved hodogram analysis, wavefield separation using median filters, and VSP deconvolution. The P-P and P-S volumes from the 3-D VSP were then obtained by VSPCDP stacking the upgoing wavefields in 3-D cells followed by f-xy deconvolution. Final P-P and P-S images from the 3-D VSP correlate well with those from the surface 3C-3D survey. Time slices from the 3- D VSP also indicate the trend of the Glauconitic sand channel of the Blackfoot field.

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