Marine pipeline installation system

A submarine pipeline installation apparatus for forming a ditch in the water bottom for a pipeline in a marine environment comprising:

• a. a supportive frame adapted to travel on the water bottom;
• b. mechanical plow means with a lowermost tip portion attached to said frame on its lower side for physically and directly cutting into and removing soils from a portion of the water bottom to form a ditch for the pipeline by pushing the soil aside;
• and
• c. sparge means attached to said frame for temporarily preventing re-entry of soil into the ditch, said sparge means being oriented for being at least generally longitudinally positioned within the ditch behind said plow means and in front of the portion of the ditch in which the pipeline is to be laid, said sparge means being an elongated, single pipe-like element attached to said frame and oriented horizontally behind and at least generally in line with the lowermost tip portion of said plow means, thereby occupying a position substantially coincident with the lowermost portion of the ditch formed by said plow means, which position will eventually be occupied by the pipeline.

The method of installing a generally rigid pipeline on the water bottom in a marine environment comprising the following steps:

• a. providing a surface vessel from which the pipeline is to be laid;
• b. providing a submarine pipeline installation apparatus on the water bottom, which installation apparatus includes a rigid frame having ditching means on its lower side for forming a ditch in the water bottom and a series of vertically declining, aligned, supportive surface means both above and behind said ditching means for movably and supportively receiving the generally rigid pipeline and laying it down substantially behind said ditching means, said supportive surface means being rigidly mounted on and carried by said frame on its upper side;
• c. running the formed pipeline from said surface vessel to said supportive surface means on said installation apparatus and ultimately to the water bottom substantially behind said ditching means with said supportive surface means providing substantially all the structural support to the pipeline after the pipeline leaves the surface vessel;
• d. simultaneously towing said installation apparatus behind said surface vessel at the same speed as the surface vessel is propelled forward as the pipeline is laid from said surface vessel to said installation apparatus to said water bottom;
• e. forming a ditch with said ditching means as said apparatus is towed into which ditch the pipeline is laid, and
• f. using said supportive surface means to guide the pipeline down in a continuously downward manner into said ditch from above substantially behind said ditching means, thereby combining the pipeline laying and the ditching operation into one simple, continuous, combined operation without the operative portions of said ditching means having to straddle the pipeline.

A submarine pipeline laying and burying system for forming a ditch and for laying a generally rigid pipeline from the water surface in the formed ditch in a marine environment in a combined operation comprising:

• a. a surface vessel from which the pipeline is to be laid;
• and
• b. a pipeline ditching apparatus located on the water bottom with the pipeline extending in a natural catenary fashion from said surface vessel to said apparatus, said apparatus including
• (i) a supportive, rigid frame on the water bottom adapted to travel on the water bottom;
• (ii) ditch forming means attached to said frame on its lower side for forming the ditch for the generally rigid pipeline in the water bottom;
• (iii) a series of vertically declining, aligned, supportive surface means for providing substantially all the structural support to the pipeline after the pipeline leaves the surface vessel but before the pipeline enters the ditch, said surface means being rigidly mounted on and carried by said frame on its upper side substantially above the operative portions of said ditch forming means, said supportive surface means being capable of movably and supportively receiving the generally rigid pipeline thereon and placing the generally rigid pipeline down in a continuously downward manner on the water bottom in the ditch substantially behind the operative portions of said ditch forming means, said supportive surface means providing at least substantially all the support to the pipeline as it is suspended in at least substantially natural, catenary fashion between said surface vessel and said apparatus;
• and
• (iv) towing means on said frame for connecting said frame to the surface vessel laying the pipeline for towing said frame with the vessel as it moves forward, the ditch being formed by said ditch forming means as said frame is towed forward by the surface vessel and the pipeline being simultaneously laid in the ditch from said supportive surfaces behind said ditch forming means, the ditching and laying operations for the pipeline being combined into one continuous operation without the operative portions of said ditching means having to straddle the pipeline.