Method for calculating the optimum vibrator spacing for ground roll reduction

A method for determining the optimal vibrator separation for improving the seismic signal-to-coherent-noise ratio by abating ground roll contamination, comprising:

• a. establishing a seismic source array including a plurality of discrete vibrator positions symmetrically spaced-apart by a first separation;
• b. distributing a plurality of seismic signal receivers at selected intervals around a quadrant of an arc centered by the array;
• c. emitting a plurality of identical chirp signals from the respective vibrator positions of said array;
• d. at each of said receivers, receiving the plurality of emitted chirp signals, stacking the plurality of received chirp signals and auto-correlating the stacked chirp signals;
• e. integrating the auto-correlated signals from all of the receivers, quantifying the level of the integrated autocorrelated signals and tabulating the quantified value of said level as a function of vibrator-position separation;
• f. symmetrically expanding the first separation between the seismic vibrator positions of the array by a selected increment a plurality of times and repeating steps b through e after each incremental expansion;
• and
• g. maximizing ground roll abatement by selecting a vibrator-position separation corresponding to the minimum tabulated signal level of the integrated auto-correlation function.