In field tests using filtered m-sequence as quasi-orthogonal pilots to drive two or four vibrator sources simultaneously, we have found that reflections on the deblended common-source gathers are somewhat degraded by vibrator-to-vibrator crosstalk and by weak artifacts with moveouts running parallel to direct arrivals. Deeper analysis of the results lead us to conclude that crosstalk can be minimized by keeping the distance between adjacent vibrators to 100m or less. Also, judicious application of localized slant stacking to the deblended common-source gathers reduces the artifact amplitudes and increases the signal-to-noise ratios of reflections. We conclude that, by following these operational and processing steps, it is possible to efficiently conduct high-resolution 3D surveys with four vibrators controlled by m-sequence pilots and running simultaneously.
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