Simultaneous marine vibrators

A method for processing seismic data from a marine seismic survey conducted using marine vibrators, the method comprising: receiving from one or more seismic receivers a first earth response to a first sweep of seismic frequencies from a first marine seismic vibrator; receiving from the one or more seismic receivers a second earth response to a second sweep of seismic frequencies from a second marine seismic vibrator, wherein the second sweep of seismic frequencies is phase shifted relative to the first sweep of seismic frequencies and the phase shift is either random with respect to seismic shots from the second seismic vibrator or random for different frequencies in the second sweep of seismic frequencies; using a multichannel filtering process to cancel one of the first and the second earth responses to produce a filtered earth response, wherein the using the multichannel filtering process to cancel one of the first and the second earth responses to produce a filtered earth response uses the phase shift of the second sweep of frequencies relative to the first sweep of seismic signals to remove cross-talk between the first and second earth responses; and using the filtered earth response to determine properties of a subterranean section of the earth. Activating a first marine seismic vibrator according to a 600 first sweep 610 Activating a second marine seismic vibrator according to a second sweep 620 Recording earth responses with receivers Processing responses to obtain a seismogram