Marine seismic data acquisition using designed non-uniform streamer spacing
The invention relates to an arrangement for seismic streamers used in the acquisition of seismic data in a marine environment where the spacing between each adjacent pair of streamers is not all the same. Some streamer spacings and/or receiver spacings are larger and some are smaller to provide a higher quality wavefield reconstruction when covering a larger total area or for a similar total area of seismic data acquisition while providing a wavefield that is optimally sampled by the receivers so that the wavefield reconstruction is suitable for subsurface imaging needs.
1. A method of acquiring seismic data in a marine environment comprising the steps of:
a. towing a system of at least four steerable streamers that are vertically and/or laterally spaced from one another, through a body of water, wherein each of the steerable streamers has a leading end and a trailing end, wherein the leading end of each streamer is spaced from the leading ends of other streamers in the system and wherein each streamer comprises a series marine seismic receivers that may be uniformly or irregularly spaced down each streamer;
b. simultaneously with step (a), configuring by use of tow cables, paravanes, doors or similar hardware attached to the system of streamers so as to tow and steer the leading end of the each streamer and/or steering the system of seismic streamers into a designed, irregular spacing configuration where the spacing between leading ends of adjacent streamers is not equal and at least one spacing is greater than five percent larger than another lateral spacing within the system and wherein the width of the system at the trailing ends of the streamers is at least five percent wider than the width of the system at the leading ends; and
c. simultaneously with steps (a) and (b), emitting seismic energy and recording reflected and/or refracted seismic data with the seismic receivers.
2. The method according to claim 1 , wherein the width of the system at the trailing ends of the streamers is at least ten percent wider than the width of the system at the leading ends.
3. The method according to claim 1 , wherein the width of the system at the trailing ends of the streamers is at least fifteen percent wider than the width of the system at the leading ends.
4. The method according to claim 1 , wherein the width of the system at the trailing ends of the streamers is at least twenty percent wider than the width of the system at the leading ends.
5. The method according to claim 1 wherein the system is towed through a survey area along a series of generally parallel paths wherein each path with the survey area has a path on either side thereof and the system is towed so that gaps between each adjacent path are avoided in both the leading ends and trailing ends.