Method of seismic surveying

Abstract

A method enables the time required to complete a seismic survey and the noises recorded in the seismic data to be reduced. One aspect of the method includes actuating a first vibrator group to start a first sweep at time T 0 ; and a second vibrator group to start a second sweep at time T 1 , wherein T 0< T 1< T 0+ S 1+ L, where S 1 is a sweep time of the first vibrator group and L is a listening time; wherein the time between the first sweep and the second sweep is T 1− T 0≧ ((n−1)*f 1* S 1 )/(n*(f 1− f 0 )) where n is a natural number, f 0 is the lower frequency limit of the vibrator sweep and f 1 is the upper frequency limit of the vibrator sweep.

1 . A method of processing slip sweep seismic data comprising:
 grouping the slip sweep seismic data into responses of at least two groups of vibrators, wherein at least one group has at least two vibrator sources;   generating impulse responses for each source in each vibrator group;   estimating the harmonic noises with cross-correlating slip sweep seismic data with a harmonic frequency sweep; and   removing the harmonic noises.   
   
   
       2 . The method of  claim 1  wherein the cross-correlated data is Fourier transformed. 
   
   
       3 . The method of  claim 1  wherein the cross-correlated data is time windowed. 
   
   
       4 . The method of  claim 1  wherein the data is Fourier transformed and time windowed. 
   
   
       5 . The method of  claim 1  wherein the harmonic frequency sweep is the same as the fundamental frequency sweep, except the sweep rate is an integer multiple of the sweep rate of the fundamental frequency sweep. 
   
   
       6 . The method of  claim 1 , wherein the slip sweep seismic data are responses to K shots at a shot location of N vibrators in M groups, where K, M, N are integers, K is at least N+1, further comprising varying the phase of the shots. 
   
   
       7 . A seismic data processing system, comprising:
 a processor; and   a computer readable media containing computer readable instructions, wherein the instructions control the processor to perform the steps of:   grouping the slip sweep seismic data into responses of at least two groups of vibrators, wherein at least one group has at least two vibrator sources;   generating impulse responses for each source in each vibrator group;   estimating the harmonic noises with cross-correlating slip sweep seismic data with a harmonic frequency sweep; and   removing the harmonic noises.