Steerable source array and method

1. A marine acoustic source array for generating an acoustic wave in a body of water, the marine acoustic source array comprising:

first and second external source sub-arrays, each sub-array including one or more individual source elements;

a first actuator device located on the first external source sub-array; and

a second actuator device located on the second external source sub-array,

wherein the first actuator device has a corresponding first cable configured to connect to a first lead-in, and the second actuator device has a corresponding second cable configured to connect to a second lead-in such that a position of the source array as a whole is controllable along a line substantially perpendicular to a path of the source array by adjusting corresponding lengths of the first and second cables, and

wherein one of the first and second lead-ins connects to a streamer and not a deflector.

2. The marine acoustic source array of claim 1 , wherein the other of the first and second lead-ins is configured to connect to streamers and not deflectors.

3. The marine acoustic source array of claim 1 , further comprising:

an internal sub-array sandwiched between the first and second external sub-arrays and configured to have an actuation device.

4. The marine acoustic source array of claim 3 , further comprising:

a third actuator device provided on the second external sub-array,

each actuator device configured to connect with a corresponding cable to an adjacent sub-array or an adjacent lead-in.

5. The marine acoustic source array of claim 4 , further comprising:

a local control mechanism provided at the first actuation device; and

a central control mechanism provided on a towing vessel.

6. The marine acoustic source array of claim 1 , further comprising:

a first pulley connected to the first cable of the first actuator device and configured to roll on the first lead-in; and

a second pulley connected to the second cable of the second actuator device and configured to roll on the second lead-in.

7. The marine acoustic source array of claim 1 , wherein the first actuator device is located on a side of a bell housing of the first external sub-array.

8. The marine acoustic source array of claim 1 , wherein the first actuator device is a winch electrically actuated with electrical energy provided from a vessel that tows the source array or from a battery located on the source array.

9. A marine acoustic source array for generating an acoustic wave in a body of water, the marine acoustic source array comprising:

first and second lead-ins configured to be towed by a vessel and to connect to streamers and not deflectors;

first and second external source sub-arrays provided between the first and second lead-ins, each sub-array including one or more individual source elements;

a first actuator device located on the first external source sub-array; and

a second actuator device located on the second external source sub-array,

wherein the first actuator device has a corresponding first cable configured to connect to the first lead-in and the second actuator device has a corresponding second cable configured to connect to the second lead-in such that a position of the source array as a whole is controllable along a line substantially perpendicular to a path of the source array by adjusting corresponding lengths of the first and second cables.

10. The marine acoustic source array of claim 9 , further comprising:

an internal sub-array sandwiched between the first and second external sub-arrays and configured to have no actuation device.

11. The marine acoustic source array of claim 9 , further comprising:

an internal sub-array sandwiched between the first and second external sub-arrays and configured to have an actuation device.

12. The marine acoustic source array of claim 11 , further comprising:

a third actuator device provided on the second external sub-array,

wherein each actuator device is configured to connect with a correspond cable to an adjacent sub-array or an adjacent lead-in.

13. The marine acoustic source array of claim 12 , further comprising:

a local control mechanism provided at the first actuation device; and

a central control mechanism provided on a towing vessel.

14. The marine acoustic source array of claim 9 , further comprising:

a first pulley connected to the first cable of the first actuator device and configured to roll on the first lead-in; and

a second pulley connected to the second cable of the second actuator device and configured to roll on the second lead-in.

15. The marine acoustic source array of claim 9 , wherein the first actuator device is a winch electrically actuated with electrical energy provided from a vessel that tows the source array or from a battery located on the source array.

16. A method for controlling a position of a marine acoustic source array that generates an acoustic wave in a body of water, the method comprising:

activating a first actuator device located on a first external source sub-array to increase or decrease a length of a first cable connected to a first lead-in, wherein the first lead-in is connected to a streamer and not a deflector; and

activating a second actuator device located on a second external source sub-array to decrease or increase a length of a second cable connected to a second lead-in such that a position of the source array as a whole is controllable along a line substantially perpendicular to a path of the source array by adjusting corresponding lengths of the first and second cables.

17. The method of claim 16 , further comprising:

actuating an actuator device of an internal sub-array sandwiched between the first and second external sub-arrays to modify a position of the internal sub-array relative to the first and second external sub-arrays.

18. The method of claim 17 , further comprising:

actuating a third actuator device provided on the second external sub-array.

19. The method of claim 18 , further comprising:

sending an actuation instruction from a central control mechanism to a local control mechanism provided at the first actuation device to actuate the first actuation device.

20. The method of claim 16 , further comprising:

rolling a first pulley connected to the first cable of the first actuator device on the first lead-in; and

rolling a second pulley connected to the second cable of the second actuator device on the second lead-in.