Geophone azimuth consistency from calibrated vertical seismic profile data

Peter Gagliardi and Don C. Lawton


Raw borehole geophone data, taken from a 3-line walkaway vertical seismic profile (VSP) acquired in the Pembina oil field in Alberta, was examined for orientation azimuth consistency. Data were recorded using a 16-level VSP tool placed at three different levels in a deviated well. An algorithm was developed that compensated for the added complexities of a deviated well. Orientation azimuths, using all three lines, had an average standard deviation of 4.39°; consistency was poorest for the mid-level tool position, and best for the shallow-level tool position. Most interestingly, orientation azimuths calculated using sources from Line 1 were, on average, 3.7° higher than Line 2 and 3.0° higher than Line 6. This was judged to be related to geological properties of the area, particularly azimuthal anisotropy.

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