A method of more accurate phase encoding of phase offset vibrators used in simultaneous-multiple-sourcing 3D seismic mapping. The method measures the actual input energy and the proxy energy thereby determining a bulk error and a frequency-dependent error, both to be applied to correct the proxy energy. The corrected proxy energy is then used to perform actual seismic survey, and the inversion is then performed using the corrected proxy energy to source separate each vibe where the error is minimized.

An initial gather of blended seismic signals induced in a common seismic receiver by a plurality of actual sources grouped in actual source groups is provided. Each actual source group has a linear source geometry that is the same for each actual source group. The plurality of sources in each actual source group is fired according to a pre-selected firing sequence that is the same for each actual source group. Actual shot records are created from the blended signals, and fictive shot records are created of seismic signals for fictive source groups that each have the same source geometry as the actual source groups, by interpolation of the actual shot records. Single source shot records of single source signals are separated by discrete deconvolution of the actual shot records and the fictive shot records. The output includes a seismic gather comprising a plurality of the single source shot records.

Seismic shot gather data is received from a computer data store for processing. The received seismic shot gather data is separated into downgoing and upgoing wavefields, a time-frequency-wavenumber (t-f-k) three-dimensional (3D) data cube comprising multiple time-frequency (t-f) slices is formed. The downgoing wavefields are wavelet transformed from a time (t) domain to a t-f domain and the upgoing wavefields are wavelet transformed from the t domain to the t-f domain. A wavelet cross-correlation is performed between the downgoing wavefields in the t-f domain and the upgoing wavefields in a t-f-k domain to generate wavelet cross-correlated data. Soft-threshold filtering if performed for each t-f slice of the t-f-k 3D data cube. An inverse wavelet transform is performed to bring wavelet cross-correlated data from the t-f-k domain to a time-receiver (t-x) domain. All seismic shots of the received seismic shot gather data are looped over and the wavelet cross-correlated data is stacked as a virtual source gather.

A survey method includes generating a first amplitude modulation signal by amplitude-modulating a carrier wave repeating the same pattern at a predetermined cycle in each of a plurality of vibrators with a modulation signal whose cycle is 1/m times the predetermined period and is different for each of the vibrators, transmitting the seismic wave based on the first amplitude modulation signal, generating a second amplitude modulation signal in one or more receivers, the second amplitude modulation signal being identical to the first amplitude modulation signal generated by any one of the seismic vibrators, generating a reception signal in each of the one or more receivers by receiving a synthetic seismic wave in which the seismic waves generated by the seismic vibrators are synthesized, calculating a correlation value between the reception signal and the second amplitude modulation signal, and analyzing characteristics of the medium on the basis of the correlation value.