System and method for deployment and retrieval of seismic nodes along a carrier rope

A system for attaching a plurality of seismic nodes along a main carrier rope comprising:

• a length measuring device for providing a measured length of deployed main carrier rope;
• a data source for providing positioning data affecting the rope position of each seismic node on the main carrier rope;
• a control unit for providing an attachment command whenever the measured length corresponds to a rope position of a seismic node computed from the positioning data;
• and
• a node attaching unit for attaching a seismic node to the main carrier rope in response to the attachment command, wherein the rope clamping device comprises a strap configured to press a body radially against the main carrier rope during the deployment period.

A system for attaching a plurality of seismic nodes along a main carrier rope comprising:

• a length measuring device for providing a measured length of deployed main carrier rope;
• a data source for providing positioning data affecting the rope position of each seismic node on the main carrier rope;
• a control unit for providing an attachment command whenever the measured length corresponds to a rope position of a seismic node computed from the positioning data;
• and
• a node attaching unit for attaching a seismic node to the main carrier rope in response to the attachment command, wherein the rope clamping device comprises a member that is movable against an inclined surface such that a radial clamping force is exerted against the main carrier rope during the deployment period.

A method for attaching a plurality of seismic node to a main carrier rope on a vessel deploying the nodes, the method comprising the steps of:

• providing a system comprising a length measuring device for providing a measured length of deployed main carrier rope, a data source for providing positioning data affecting the rope position of each seismic node on the main carrier rope, a control unit for providing an attachment command whenever the measured length corresponds to a rope position of a seismic node computed from the positioning data, and a node attaching unit for attaching the seismic node to the main carrier rope in response to the attachment command;
• a) computing a rope position for each seismic node from geotechnical requirements, topology and other data affecting the position of the seismic nodes on the seafloor;
• b) performing a start procedure which includes controlling the vessel position and speed, and deploying a first end of the main carrier rope;
• c) maintaining the main carrier rope running at an essentially constant velocity with respect to the vessel;
• d) measuring the length of the main carrier rope deployed during the deployment;
• e) attaching a seismic node to the main carrier rope whenever the measured length corresponds to a computed rope position for the seismic node, wherein the seismic node is attached using the node attaching unit, and wherein each seismic node is attached to a fly line at each of two opposing ends, each fly line is connected to a suspension device that is rotatable about the main carrier rope, and two detachable rope clamping devices are affixed to the main carrier rope between the suspension devices such that the seismic node is maintained at a fixed rope position until the rope clamping devices are intentionally released;
• f) repeating steps d)-e) until a predetermined number of seismic nodes are attached to the main carrier rope;
• and
• g) performing an end procedure which includes deploying a second end of the main carrier rope.