Seismic acquisition method and apparatus
The presently disclosed seismic acquisition technique employs a receiver array and a processing methodology that are designed to attenuate the naturally occurring seismic background noise recorded along with the seismic data during the acquisition. The approach leverages the knowledge that naturally occurring seismic background noise moves with a slower phase velocity than the seismic signals used for imaging and inversion and, in some embodiments, may arrive from particular preferred directions. The disclosed technique comprises two steps: 1) determining from the naturally occurring seismic background noise in the preliminary seismic data a range of phase velocities and amplitudes that contain primarily noise and the degree to which that noise needs to be attenuated, and 2) designing an acquisition and processing method to attenuate that noise relative to the desired signal.
1. A method for use in marine seismic acquisition, comprising:
deploying a receiver array oriented in a first direction, wherein the receiver array comprises a plurality of sparsely spaced receiver lines oriented in the first direction, and wherein each of the receiver lines comprises a plurality of densely positioned lines of receiver nodes;
shooting a plurality of seismic signals from a plurality of seismic sources along a plurality of sparsely positioned sail lines, wherein each of the sail lines are oriented in a second direction orthogonal to the first direction; and
recording returned energy of the seismic signals.
2. The method of claim 1 , wherein deploying the sparse receiver array includes deploying nodes of seismic receivers that are spaced about 4 kilometers (km) apart.
3. The method of claim 1 , wherein shooting the plurality of seismic signals includes shooting the seismic signals from positions spaced about 150 meters (m) apart along the sail lines.
4. The method of claim 1 , wherein the sail lines are spaced about 1 kilometers (km) apart.
5. The method of claim 1 , wherein shooting the plurality of seismic signals includes shooting a plurality of frequency humming seismic signals.
6. The method of claim 1 , wherein the seismic signals are low frequency seismic signals.