| 摘要 |
The invention concerns a method for performing a repeated, i.e. four-dimensional, marine seismic survey. This includes towing at least one seismic source 15 behind a seismic survey vessel 10 substantially along the path of a previously conducted seismic survey, determining the position of the seismic source 15 during the repeated marine seismic survey, e.g. using GPS receivers mounted on seismic source arrays A, B, and comparing the determined position of the seismic source with a position of a seismic source recorded during a previously conducted seismic survey. The position of the at least one seismic source is adjusted in response to said comparison using a deflector 18 connected to the keel (bottom) of a buoy (float) 13 supporting each subarray A1, A2, A3, B1, B2, B3. A deflector control assembly (24, Fig. 2A) enables the angle of attack (22) between deflector 18 and buoy 13 to be varied by controlling an actuator arm (34). The invention may be performed in a manual or an automatic mode. |
