Apparatus and methods for loading and unloading of sensor capsules

1. An apparatus for attaching or detaching a sensor capsule to and from a running seismic cable on a vessel, wherein the apparatus comprises:

a trolley with at least one room for a sensor capsule, wherein the trolley is moveable back and forth on a support structure in a longitudinal direction essentially corresponding to the longitudinal direction of the seismic cable during deployment and retrieval;

a latching mechanism for latching the trolley temporarily to a node casing forming part of the seismic cable; and

at least one inserting/withdrawing mechanism for inserting and withdrawing the sensor capsule into or out of the node casing while the trolley is latched to the node casing.

2. The apparatus of claim 1 , wherein the latching mechanism is centrally located at the seismic cable and the room for the sensor capsule and a corresponding inserting/withdrawing mechanism is located at a distance from the latching mechanism in a lateral direction perpendicular to the longitudinal direction.

3. The apparatus of claim 2 , wherein the trolley comprises a first room on a first side of the latching mechanism and a second room on the opposite side of the latching mechanism.

4. The apparatus of claim 2 , wherein the inserting/withdrawing mechanism is movable back and forth on the trolley in the lateral direction.

5. The apparatus of claim 3 , wherein the inserting/withdrawing mechanism is movable back and forth on the trolley in the lateral direction.

6. The apparatus of claim 4 , wherein the support structure comprises a track extending in the longitudinal direction and configured for guiding the inserting/withdrawing mechanism in the lateral direction toward the seismic cable during deployment and away from the seismic cable during retrieval.

7. The apparatus of claim 6 , wherein the track has an end that extends parallel to the seismic cable.

8. The apparatus of claim 4 , wherein the inserting/withdrawing mechanism is moved in the lateral direction by electromechanical or pneumatic means.

9. The apparatus of claim 1 , wherein the latching mechanism comprises at least one latch pin that is movable between a retracted position where the trolley is free relative to the node casing, and an extended position for latching the trolley to the node casing.

10. The apparatus of claim 1 , further comprising a robot for supplying and removing sensor capsules to/from the inserting/withdrawing mechanism.

11. A method for attaching sensor capsules to a running seismic cable on a vessel, during deployment of the seismic cable from a reel into the sea, wherein the method comprises:

i) moving a trolley with an inserting/withdrawing mechanism for the sensor capsules to a reel-position;

ii) supplying a sensor capsule to the inserting/withdrawing mechanism;

iii) latching the trolley to a node casing forming part of the seismic cable;

iv) inserting the sensor capsule into the node casing by the inserting/withdrawing mechanism while the seismic cable with the node casing and the trolley is moving towards the sea; and

v) releasing the trolley from the node casing.

12. The method of claim 11 , wherein inserting the sensor capsule into the node casing comprises using a track for guiding the inserting/withdrawing mechanism in a lateral direction toward the seismic cable while the trolley is moving toward the sea.

13. The method of claim 11 , wherein supplying the sensor capsule to the inserting/withdrawing mechanism is carried out by a robot.

14. A method for detaching sensor capsules a running seismic cable on a vessel during retrieval of the seismic cable from the sea onto a reel, wherein the method comprises:

i) moving a trolley with an inserting/withdrawing mechanism for the sensor capsules to a sea-position;

ii) latching the trolley to a node casing forming part of the seismic cable;

iii) withdrawing a sensor capsule from the node casing by the inserting/withdrawing mechanism while the seismic cable with the node casing and the trolley is moving from the sea;

iv) releasing the trolley from the node casing; and

v) removing the sensor capsule from the inserting/withdrawing mechanism.

15. The method of claim 14 , wherein withdrawing the sensor capsule from the node casing comprises using a track for guiding the inserting/withdrawing mechanism in a lateral direction away from the seismic cable while the trolley is moving away from the sea.

16. The method of claim 14 , wherein removing the sensor capsule from the inserting/withdrawing mechanism is carried out by a robot.