Steerable source systems and method

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

a first marine acoustic source array having first and second external source sub-arrays, each sub-array including one or more individual source elements and a cable connecting to a vessel;

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

a first rope connecting the first actuator device to a first lead-in that is configured to connect to a head of a streamer,

wherein the first actuator device is configured to control a length of the first rope in order to control a position of the first source array relative to the streamer.

2. The marine acoustic source system of claim 1 , wherein the first lead-in is configured to directly connect to a head of the streamer and not to directly connect to a deflector.

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

an internal sub-array sandwiched between the first external sub-array and the second external sub-array and configured to have a second actuation device that connects with a second rope to the first external sub-array.

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

a third actuator device provided on the second external sub-array and having a third rope that connects to the internal sub-array.

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

a local control mechanism provided at the first actuation device and configured to actuate the first actuator device; or

a central control mechanism provided on a towing vessel and configured to actuate the first actuator device.

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

a first slider connected to the first rope of the first actuator device and configured to roll on the first lead-in.

7. The marine acoustic source system of claim 1 , wherein the first actuator device is connected to a side of a bell housing of the first external sub-array, wherein the bell housing is a rigid structure, or the first actuator is connected to a bend restrictor provided in front of the bell housing.

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

9. The marine acoustic source system of claim 1 , further comprising:

a deflector connected to the second external source sub-array and configured to maintain a distance between the first and second external source sub-arrays substantially constant when a length of the first rope varies.

10. The marine acoustic source system of claim 9 , wherein each sub-array includes a corresponding actuator device and each actuator device has a corresponding rope that connects to an adjacent sub-array or lead-in.

11. The marine acoustic source system of claim 1 , further comprising:

a second rope fixedly connected with one end to the first sub-array and movably connected with the other end to a slider, where in the slider is configured to freely move along the first lead-in.

12. The marine acoustic source system of claim 1 , further comprising:

a fairing provided on the first rope.

13. The marine acoustic source system of claim 1 , further comprising:

an internal sub-array provided adjacent to the first external sub-array and connected with a cable to the first external sub-array; and

a deflector attached to a head of the internal sub-array.

14. The marine acoustic source system of claim 1 , wherein the first actuator device has a rotating spool configured to rotate about an axis that extends substantially along the first external sub-array or the axis is substantially perpendicular to the first external sub-array.

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

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

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

a first actuator device located on the first source array; and

a second actuator device connected to the second source array,

wherein the first actuator device has a first cable configured to connect to the first lead-in and the second actuator device has a second cable configured to connect to the second lead-in such that positions of the first and second source arrays are controllable along a line substantially perpendicular to a path of the source system.

16. The marine acoustic source system of claim 15 , further comprising:

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

17. The marine acoustic source system of claim 16 , further comprising:

a local control mechanism provided at the first actuation device of the first source array and configured to control the first actuation device; or

a central control mechanism provided on a towing vessel and configured to control the first actuation device.

18. The marine acoustic source system of claim 15 , further comprising:

a first slider connected to the first rope of the first actuator device of the first source array and configured to roll along the first lead-in; and

a second slider connected to the second rope of the second actuator device of the second source array and configured to roll along the second lead-in.

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

20. The marine acoustic source system of claim 15 , further comprising:

a second rope fixedly connected with one end to a first sub-array of the first source array and movably connected with the other end to a slider, wherein the slider is configured to freely move along the first lead-in.

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

positioning a first source array for towing in water; and

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