A process for acquiring marine seismic data and provide information about geologic structures in the earth, wherein the process comprises: a) providing a plurality of seismic receivers to receive seismic energy; b) providing a plurality of source arrays, each source array comprising a plurality of pulse-type seismic sources of different sizes (20a, 20b, 20c) to emit pulses of seismic energy into the earth; c) firing series of pulses of seismic energy into the earth to create a seismic energy wavefield response from geologic structures in the earth; d) receiving seismic energy with the plurality of seismic receivers including the seismic energy wavefield response form the geologic structures in the earth; e) recording the seismic energy wavefield response received by the seismic receivers to form data traces; characterised in that f) the pulse-type sources in each source array are fired in a continual or near continual loop of distinctive composite sequences of pulses of seismic energy, wherein no more than half of the pulse-type seismic sources in a source array are fired in unison; wherein the composite sequences of pulses within the loop are distinctive one from another and are delivered in a planned, non-repeating order, where the loop is of sufficient length to provide listening time to receive the wave field response from the geologic structures in the earth from a composite sequence of pulses (A, B, C, D) in the loop before the loop is restarted; and g) wherein the step of firing series of pulses creates a first loop of distinctive composite sequences of pulses, and wherein the process further comprises firing a continual or near continual loop of distinctive composite sequences of pulses from a second source array which creates a second loop wherein the first loop is distinctive from the second loop, wherein the composite sequences of pulses within the first and second loops are sufficiently distinctive so as to distinguish the wavefield caused by the first loop from seismic energy in the environment that arises from the wavefield caused by the second loop; h) the step of recording the seismic energy includes recording seismic energy from wave fields created by the first loop and the second loop and the step of processing further includes separating the wavefield response in the data traces based on the source of the first loop from the source of the second loop; and i) processing the data traces of recorded seismic energy to separately identify within the data traces the composite sequences of pulses of the pulse-type seismic sources when the composite sequences of pulses (A, B, C, D) were fired. a) providing a plurality of seismic receivers to receive seismic energy; b) providing a plurality of source arrays, each source array comprising a plurality of pulse-type seismic sources of different sizes (20a, 20b, 20c) to emit pulses of seismic energy into the earth; c) firing series of pulses of seismic energy into the earth to create a seismic energy wavefield response from geologic structures in the earth; d) receiving seismic energy with the plurality of seismic receivers including the seismic energy wavefield response form the geologic structures in the earth; e) recording the seismic energy wavefield response received by the seismic receivers to form data traces; characterised in that f) the pulse-type sources in each source array are fired in a continual or near continual loop of distinctive composite sequences of pulses of seismic energy, wherein no more than half of the pulse-type seismic sources in a source array are fired in unison; wherein the composite sequences of pulses within the loop are distinctive one from another and are delivered in a planned, non-repeating order, where the loop is of sufficient length to provide listening time to receive the wave field response from the geologic structures in the earth from a composite sequence of pulses (A, B, C, D) in the loop before the loop is restarted; and g) wherein the step of firing series of pulses creates a first loop of distinctive composite sequences of pulses, and wherein the process further comprises firing a continual or near continual loop of distinctive composite sequences of pulses from a second source array which creates a second loop wherein the first loop is distinctive from the second loop, wherein the composite sequences of pulses within the first and second loops are sufficiently distinctive so as to distinguish the wavefield caused by the first loop from seismic energy in the environment that arises from the wavefield caused by the second loop; h) the step of recording the seismic energy includes recording seismic energy from wave fields created by the first loop and the second loop and the step of processing further includes separating the wavefield response in the data traces based on the source of the first loop from the source of the second loop; and i) processing the data traces of recorded seismic energy to separately identify within the data traces the composite sequences of pulses of the pulse-type seismic sources when the composite sequences of pulses (A, B, C, D) were fired.