Reel type pipeline laying ship and method

A pipe laying ship comprising:

• a) a dynamically positioned hull having bow, stern, and deck portions, a deck moon pool opening through which a pipeline can be launched for laying on a seabed;
• b) a pair of reels supported upon the deck next to the moon pool opening, each reel being independently rotatable, the reels being generally positioned port and starboard relative to one another;
• c) one or more pipeline welding stations on the deck and positioned to weld joints of pipe together to form a pipeline that can be wound upon a selected reel;
• d) a tower for guiding a welded pipeline from a selected reel, the tower being positioned next to the moon pool and including at least a bend controller, a straightener and a tensioner;
• and
• e) wherein the welding stations and tower are each movable between port and starboard positions that enable a pipeline to be welded and then wound upon either of the reels and to be unwound from either of the reels for launching to the seabed.

A pipe laying ship comprising:

• a) a dynamically positioned barge or self propelled dynamically positioned hull having a deck having a bow, a stern and a moon pool opening amidships;
• b) a pair of reels supported upon the deck next to the moon pool opening and behind the moon pool opening, each reel being independently rotatable and configured to hold a pipeline independently of the other reel;
• c) one or more pipeline welding stations on the deck behind the reels, the pipeline welding stations being positioned to weld joints of pipe together to form a pipeline that can be wound upon a selected reel;
• d) a pipe bending device on the deck for bending pipe that is to be wound upon a selected reel;
• e) a tower for guiding a welded pipeline as it is unwound from a selected reel, the tower including a bend controller, a straightener and a tensioner;
• and
• f) wherein the welding stations and tower are laterally movable between positions that enable a pipeline to be welded and wound upon either the port or starboard reel and to be unwound from either the port or starboard reel for launching to the seabed.

A method of laying a pipeline on a seabed, comprising the steps of:

• a) progressively joining together lengths of pipe upon the deck of a vessel at a firing line to form a long pipeline, the vessel having a pair of reels and a tower for launching the pipeline;
• b) winding the pipeline upon a selected reel of the pair of reels as the lengths of pipe are joined together at the firing line;
• c) bending the pipeline to approximate the curvature of the reel before winding the pipeline upon the selected reel;
• d) after a selected reel is wound with a pipeline of selected length, moving the selected reel along a path in which the pipeline is to be laid, while unwinding the pipeline from the reel and simultaneously straightening the pipeline;
• e) wherein the pair of reels are independently rotatable so that either reel can be wound with a pipeline in step “a”, independently of the other;
• f) moving the firing line in a port to starboard direction that aligns the pipeline as it is being formed with a selected reel during the winding step “b”;
• and
• g) moving the tower in a port to starboard direction that aligns the tower with a selected reel during unwinding step “b”.