Seismic streamers which attentuate longitudinally traveling waves
A seismic streamer includes at least one array of sensors each disposed in a sensor holder at longitudinally spaced apart locations. A longitudinal orientation of at least one sensor or at least one sensor holder is different from that of the other sensors along the length of the array.
1. A seismic streamer, comprising:
at least one array of seismic sensors disposed at longitudinally spaced apart locations, a longitudinal orientation of directional sensitivity of at least one sensor in the array being opposite to a longitudinal orientation of directional sensitivity of other sensors in the array, signal outputs from the sensors in the array combined to generate an array output signal.
2. The streamer of claim 1 further comprising:
a jacket covering an exterior of the streamer;
at least one strength member extending along the length of the jacket, the strength member disposed inside the jacket; and
an acoustically transparent material filling void space in the interior of the jacket.
3. The streamer of claim 2 wherein the material comprises curable, synthetic urethane-based polymer introduced into the jacket in liquid form and cured thereafter.
4. The streamer of claim 1 wherein the orientations of the sensors are arranged longitudinally symmetrically about a longitudinal center of the at least one array.
5. The streamer of claim 1 wherein the at least one array comprises hydrophones.
6. The streamer of claim 1 wherein each sensor is disposed in a holder comprising a passage therein for the sensor, the passage closed at one longitudinal end.
7. The streamer of claim 1 wherein the longitudinal orientations of the sensors alternates along the array.
8. The streamer of claim 1 wherein each sensor is disposed in a holder comprising a longitudinal passage therein for the sensor, the passage closed at one longitudinal end, the closed longitudinal end of at least one holder oriented opposite to a closed longitudinal end of the other holders.
9. The streamer of claim 8 wherein the orientation of the longitudinally closed ends of the holders alternates along the array.
10. The streamer of claim 9 wherein the longitudinally closed ends are arranged symmetrically about a longitudinal center of the array.
11. The streamer of claim 1 wherein each sensor is disposed in a sensor holder, a longitudinal orientation of at least one sensor holder opposite to a longitudinal orientations of the other sensor holders.
12. The streamer of claim 11 wherein the sensor holders are longitudinally alternatingly oriented.
13. The streamer of claim 11 wherein the sensor holders are arranged longitudinally symmetrically about a longitudinal center of the array.
14. A seismic streamer, comprising:
a jacket covering an exterior of the streamer;
at least one strength member extending along the length of the jacket, the strength member disposed inside the jacket;
at least one array of sensors disposed inside the jacket along the strength member, each sensor in the at least one array disposed in a sensor holder, each sensor holder configured to expose the sensor to pressure variations in the interior of the jacket in only one longitudinal direction and to acoustically isolate the sensor from pressure variations from the other longitudinal direction, the direction of exposure of at least one sensor holder being opposite to a direction of exposure of the other holders in the array, whereby a sensor disposed in said at least one sensor holder has a longitudinal orientation of directional sensitivity opposite to a longitudinal orientation of direction sensitivity of other sensors in the array disposed in sensor holders in which the direction of exposure is opposite to the direction of exposure of said at least one sensor holder; and
an acoustically transparent material filling void space in the interior of the jacket.
15. The streamer of claim 14 wherein the at least one array is arranged such that directions of exposure of the holder are symmetric about a longitudinal center of the at least one array.
16. The streamer of claim 14 wherein the material comprises curable, synthetic urethane-based polymer introduced into the jacket in liquid form and cured thereafter.
17. The streamer of claim 14 wherein the sensors in the at least one array comprise hydrophones coupled in series.
18. The streamer of claim 14 wherein each sensor holder comprises a passage for a respective sensor, the passage closed at one longitudinal end.
19. The streamer of claim 14 where in the direction of exposure alternates along the array.
20. The streamer of claim 14 wherein a longitudinal orientation of at least one sensor is opposite to longitudinal orientations of the other sensors in the array.
21. The streamer of claim 19 wherein longitudinal orientations of the sensors alternate along the array.
22. The streamer of claim 20 wherein the longitudinal orientations of the sensors are arranged symmetrically with respect to a longitudinal center of the array.
23. A seismic streamer, comprising:
a jacket covering an exterior of the streamer;
at least one strength member extending along the length of the jacket, the strength member disposed inside the jacket;
at least one array of sensors disposed inside the jacket along the strength member, each sensor in the at least one array disposed in a sensor holder, the sensors having signal outputs thereof combined to generate an array output signal, at least one sensor holder oriented longitudinally opposite to orientation of other sensor holders in the array, whereby a sensor disposed in said at least one sensor holder has a longitudinal orientation of directional sensitivity opposite to a longitudinal orientation of direction sensitivity of other sensors in the array disposed in sensor holders in which the direction of exposure is opposite to the direction of exposure of said at least one sensor holder; and
an acoustically transparent material filling void space in the interior of the jacket.
24. The streamer of claim 21 wherein the at least one array is arranged such that orientations of the holder are symmetric about a longitudinal center of the at least one array.
25. The streamer of claim 21 wherein the material comprises curable, synthetic urethane-based polymer introduced into the jacket in liquid form and cured thereafter.
26. The streamer of claim 21 wherein the sensors in the at least one array comprise hydrophones.
27. The streamer of claim 21 wherein each sensor holder comprises a passage for a respective sensor, the passage closed at one longitudinal end.
28. The streamer of claim 21 where in the orientation of the sensor holders alternates along the array.
29. The streamer of claim 21 wherein a longitudinal orientation of at least one sensor is opposite to an orientation of the other sensors in the array.
30. The streamer of claim 27 wherein longitudinal orientations of the sensors alternate along the array.
31. The streamer of claim 28 wherein the longitudinal orientations of the sensors are arranged symmetrically with respect to a longitudinal center of the array.